Surgical Dermatology

Skin Lines
1) Langers lines
- how do the lines run in relation to underlying muscle?
2) Relaxed skin tension lines
- how do these lines run in relation to underlying muscles?

Which of these lines should incision be made with?
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Terms in this set (123)
• Skin lines
■ Langer's lines: lines along skin that will gape when punctured with a spike; lines run parallel to
underlying muscles
○ Different than relaxed skin tension lines (frequently perpendicular to them, in fact)
■ Relaxed skin tension lines (Kraissl and Borges lines):
lines that run perpendicular to underlying muscles; most
elective incisions should be made parallel to these lines
Arterial supply
○ Face receives blood from both the internal and external carotid systems:

External carotid:
- supplies mid and lower face; most important branches include:
-- Superficial temporal artery: supplies temple, scalp, and lateral forehead
-- Maxillary artery: gives rise to both the infraorbital and mental arteries, which
supply the mid face, nasal dorsum, lower lip, and chin
Infraorbital artery anastomoses with the internal carotid-derived arteries
(supratrochlear and supraorbital arteries)
-- Facial artery: gives rise to both the superior and inferior labial arteries, which supply the upper and lower lips, chin, nasal ala, and columella
Facial artery continues medially deep to the melolabial fold, where it gives rise to the angular artery near the base of the ala ➔ this area is susceptible to intraarterial injection during filler injection!
Facial artery (angular artery specifically) eventually ends in anastomoses with branches of the internal carotid (dorsal nasal artery specifically) near the medial canthus
Internal carotid: supplies mid forehead and anastomoses with branches of the external carotid
in the area of the medial canthus and dorsal nose
- Ophthalmic artery: responsible for most of the facial arteries supplied by the internal carotid. It travels through the optic canal into the orbit where it supplies the retinal, supraorbital and supratrochlear (axial artery required for paramedian forehead flap), infratrochlear, dorsal nasal (anastamoses with angular artery), external nasal, anterior and posterior ethmoidal, and lacrimal branches. These branches supply the retina, forehead, upper dorsal nose, and eyelids.
Branches of the ophthalmic artery anastomose heavily with those supplied by the external carotid system

These anastomoses are important when inadvertent intraarterial injection of steroids or fillers occurs. Glabellar area is at highest risk, because of the underlying supratrochlear artery and its anastomoses
➔ may lead to skin necrosis or blindness
(from communication with retinal artery)
■ Venous system
○ Veins typically follow their associated arteries
○ Supratrochlear and supraorbital veins drain through the orbit and into the cavernous sinus
Danger triangle: area extending from the two corners of the mouth to nasal bridge; infections
in this area can cause cavernous sinus thrombosis, meningitis, and brain abscesses

■ Lymphatic system
○ Mostly important for detection of stage 3 skin cancer metastases originating from head/neck
- Forehead, lateral temporal, frontal, and periocular areas drain into to the upper jugular nodes
- Medial midface drains into the submandibular nodes
- Lower face drains into the submental nodes
■ Superficial musculoaponeurotic system (SMAS)
○ Composed of muscles and fascia of the face and neck; allows for distributed force of muscles in
facial expression and helps contain infection to superficial areas
○ Motor nerves all run deep to SMAS ➔ staying above SMAS during facial surgery prevents motor
nerve damage
○ Sensory nerves are located superficial to SMAS ➔ often transected during facial surgery ➔ numbness
■ Sensory nerves (Tables 8-1, 8-2, Figs. 8-1, 8-2, 8-3, and 8-4)
○ Sensory innervation of face is almost entirely supplied by branches of the CN V (trigeminal nerve)
○ Boards factoid: Damage to CN V may result in trigeminal trophic syndrome and Frey's syndrome
○ Clinical pearl: injection of anesthetic into the supraorbital, supratrochlear, infraorbital, and mental foramens will result in prolonged anesthesia for vast majority of face (exceptions = parts of nose and angles of mouth)

■ Motor innervation (Tables 8-3, 8-4 and Fig. 8-5)
○ Muscles of facial expression are innervated by CN VII (facial nerve); facial muscles receive motor innervation from their underside
Boards Factoid: as a minor function, CN VII also provides sensory input for anterior tongue (via
chorda tympani branch) and a small amount of the external auditory meatus
○ Facial nerve emerges from the stylomastoid foramen; the nerve travels within the parotid
gland and then splits into 5 branches: temporal, zygomatic, buccal, mandibular, and cervical
branches ("To Zanzibar By Motor Car")
Frontal nerve (two divisions)
- Supraorbital (upper eyelid, majority of forehead, and frontal to vertex scalp)
- Supratrochlear (medial upper eyelid, medial forehead, and frontal scalp)

Nasociliary nerve (3 important divisions)
-Infratrochlear (nasal root, medial canthus)
-Anterior ethmoidal (distal/inferior half of central nose: dorsum, supratip, tip, and columella)
- Ciliary (corneal surface)

Lacrimal nerve (lateral eyelid, conjunctiva, and lacrimal gland)

Supraorbital nerve danger zone (recently described): nerve courses superficially at vertical distances above the palpable orbital rim of 1.3 cm or greater ➔ nerve easily injured during a deep shave, punch or ED&C of lower to midforehead ➔ paresthesia, traumatic neuroma

Supraorbital and supratrochlear nerves are commonly anesthetized via nerve block

Hutchinson's sign: involvement of nasociliary branch by
VZV (distal nasal vesicles, ulcers) is almost always
a/w herpes zoster ophthalmicus; conversely, it is very
rare to have ocular involvement in absence of distal nasal
skin lesions!
Auriculotemporal nerve (superior portion of anterior external ear and auditory canal, temple, temporoparietal scalp, TMJ, outer aspect of tympanic membrane, and parasympathetic innervation of parotid)

Buccal nerve (buccal mucosa, angle of mouth, and gingiva)

Inferior alveolar nerve (mandibular teeth)

Mental nerve (chin and lower lip)

Lingual nerve (somatic sensation to anterior 2/3 of tongue, floor of mouth, and lower gingiva)

Auricolotemporal nerve is frequently injured during TMJ surgery (➔ paresthesia of ear and temple) and parotidectomy (➔ injured parasympathetic nerves erroneously reattach to sweat glands in area ➔ Frey syndrome)
Mental nerve is commonly anesthetized via nerve block
Mandibular nerve (V3) also provides motor innervation to muscles of mastication (masseter, pterygoid, temporalis, etc.)
In decreasing order of area:
Great auricular: majority of posterior ear, and 3/4 of anterior ear (all except the quadrant innervated by auriculotemporal, and the area innervated by cranial nerves)

Auriculotemporal: entire "anterior-superior quadrant of ear" (excluding conchal bowl, but including EAM), and superior portion of posterior helix

Cranial nerves (VII, IX, X): Conchal bowl and EAM (most important); also contributes to posterior notch innervation

Lesser occipital: posterior notch

Ring block around ear anesthetizes everything except conchal bowl and EAM
Hand - name the nerves involved - How do you perform a nerve block of these nerves? How much anesthetic do you use?Median, radial, and ulnar Opposing the thumb and fifth finger makes the palmaris longus tendon apparent; typically use 3-5 mL of anesthetic Median nerve block: inject at proximal wrist crease, between palmaris longus and flexor carpi radialis tendons (i.e., inject on the radial to palmaris longus, at the proximal wrist crease) Ulnar nerve block: inject immediately radial to flexor carpi ulnaris at proximal wrist crease Radial nerve block: inject along the proximal wrist crease, starting immediately lateral to radial artery, extending all the way to dorsal midwristFoot - name the important nerves and where the injections to block them goPosterior tibial, saphenous, sural, superficial peroneal, and deep peroneal Sites for foot block are highly testable! Posterior tibial nerve: inject in groove between medial malleolus and Achilles tendon; is posterior to posterior tibial artery Sural nerve: inject in groove between lateral malleolus and Achilles tendon Deep peroneal: inject lateral to hallucis longus tendon (down to bone); may also inject SQ between second and first toe Saphenous and superficial peroneal: inject on dorsal foot, subcutaneously, from malleolus to malleolusFingers - how many nerves per digit? - how do you perform digital block? - how much lidocaine can you use? is it safe to use Epi? unless what?Two dorsal and two ventral nerves per digit Multiple ways to perform digital block Classic technique: inject immediately distal MCP/MTP, using 1-2 mL on each side (2-4 mL total per digit); do NOT exceed 8 mL per digit (risk of tourniquet effect) - Safe to use lidocaine with epinephrine, unless patient has underlying vasoocclusive diseaseTounge - describe the taste innervation - describe the sensory innervation - describe the motor innervation how do you perform a block of the penile nerves?Tongue Taste: CN VII (chorda tympani branch; anterior 2/3) Somatic sensory: trigeminal V3 (lingual nerve; anterior 2/3) Glossopharyngeal (CN IX) provides both taste and somatic sensation to posterior 1/3 of tongue Motor innervation of tongue: predominantly CN XII (hypoglossal nerve) Penis Dorsal nerve of penis bifurcates into major anterior (dorsal) and minor posterior (ventral) branches at the base of the penis ➔ these branches supply almost all of penis Injecting a ring of lidocaine around the base of penis anesthetizes all of penis, except periurethral glansFacial Nerve - name the 5 branches - The Temporal supplies innervation to which muscles?Temporal zygomatic Buccal marginal mandibular cervical Temporal Frontalis (eyebrow elevation) Corrugator supercilii (pulls eyebrows inferomedially) Upper portion of orbicularis occuli (tight closure of eyelids, blinking) Nerve injury related findings: Inability to elevate eyebrows ➔ eyebrow ptosis Targets for Botox: Frontalis (horizontal forehead wrinkles) Orbicularis ("crow's feet") Corrugator supercilii (vertical glabellar lines, scowling appearance)zygomatic - supplies what muscles - what muscle that botox is a target for is supplied by this nerveOrbicularis occuli (lower portion) Nasalis, alar portion (flares nostrils) Procerus (foreshortening of nose, "horizontal glabellar lines") Upper lip muscle(s): Zygomaticus major (mouth angle retractor/elevator, main muscle responsible for smiling) Inability to tightly shut eyes (+/− lower lid ectropion), flare nostrils, and elevate upper lip Targets for Botox: Procerus ("horizontal glabellar lines") Nasalis, alar portion (flared nostrils)Buccal - list issues related to nerve injury - list the targets for botox?Buccinator (important muscle of mastication, works with orbicularis oris to keep cheeks pressed tightly against teeth ➔ prevents food accumulation; also allows for high-pressure blowing) Depressor septi nasi (pulls columella toward lip) Nasalis, transverse portion ("bunny lines") Upper lip muscles: Orbicularis oris (pursing/puckering of lips, apposition of corners of mouth, pulls the lips tight up against teeth, and is required for clear speech) Zygomaticus major and minor (mouth angle retractors/ elevators, main muscles responsible for smiling!) Risorius (mouth angle retractor/elevator, a lesser role in smiling) Levator anguli oris (mouth angle retractor/elevator) Levator labii superioris (elevates and everts upper lip, responsible for "gummy smile") Levator labii superioris alaque nasi (flares nostril and elevates upper lip) Lower lip muscle(s): Orbicularis oris Nerve Injury Related findings: Food accumulation between cheek and teeth Uneven facial expression at rest and with smiling (vs only upon smiling with marginal mandibular) Inability to pucker/purse lips Drooling as a result of ↓lip sealing ability Speech is muffled, cannot enunciate letters M, V, F, P, and O ↓ability to wrinkle nose (↓bunny lines) Damage to the buccal branch of CN VII is the most likely to cause eating problems (food accumulation + drooling) and muffled speech Targets for Botox: Levator labii superioris ("gummy smile") Nasalis, transverse portion ("bunny lines")Marginal Mandibular - is at highest risk for what? - describe what happens when injuredMarginal mandibular Lower lip muscles: Orbicularis oris Depressor anguli oris (lip depressor/retractor) Depressor labii inferioris (lip depressor/retractor) Mentalis (lower lip protrusion, chin elevator) Platysma, upper portion (intercalates with lip depressors/ retractors) Face appears normal at rest but asymmetric when smiling Drooling Inability to evert lower lip Marginal mandibular is at highest risk of causing permanent motor deficits because has only 1-2 rami (in contrast to multiple rami for zygomatic and buccal branches) and is covered by thin skin and thin platysmaCervical Branch of the Facial Nerve - innervates what structure?Cervical Platysma (depresses lower jaw, tenses neck skin) ↓ability to depress lower jaw to express melancholy ("grimacing") Botox can be used to target platysma ("platysmal bands")Scalpel Handles - what are the two scalpel handle options? which is most common■ Bard-Parker standard handle (most common): flat; holds common blades such as the #15, #11, and #10 ■ Beaver handle: round or hexagonal; holds smaller, sharper blades; useful for confined spaces or delicate tissueScissors Scissors■ Basics ○ Short-handled scissors useful for delicate work ○ Long-handled scissors extend the surgeons reach and are useful for undermining ○ Curved blades useful for undermining cysts ○ Straight blades useful for trimming tissue and cutting sutures ○ Serrated blades grab tissue better ○ Sharp-tipped scissors puncture tissue easily and are best for dissection ○ Blunt-tipped scissors are best for delicate underminingScissor Types - Iris scissors: Describe, best for what? - Gradle scissors: Describe, best for what? - westcott scissors: Describe, similar to what? good for what? - Mayo Scissors: Describe: best for what? - Metzenbaum scissors: describe - supercut scissors: available on what scissors? Purpose, how are they denoted?○ Iris scissors: sharp-tipped and short-handled; blades may be straight or curved; best for sharp dissection ○ Gradle scissors: similar to iris but blades curved and tapered to a fine point at tip; best for dissection of delicate tissue such as periorbital skin ○ Westcott scissors: spring-loaded instrument similar in appearance to Castro-Viejo; good for delicate eyelid dissection ○ Mayo scissors: characterized by its ~1:1 handle-to- blade ratio; primary purpose is coarse dissection ○ Metzenbaum scissor: long handles with blunt tips ➔ useful for blunt dissection in areas that require long reach ○ Supercut scissors: one blade has a razor edge; "supercut" blades are available on most scissor types listed above and often are denoted with black handlesNeedle Drivers - what is the advantage to smooth handled needle drivers? disadvantages - What are the advantage to larger needle drivers with teeth?○ Smaller needle drivers with smooth jaws Ideal for small, delicate needles Advantages: smooth jaws have ↓risk of tearing small sutures (6-0 and smaller) and are less damaging to fine needles (P-3 and smaller) Disadvantages: needles not grasped as tightly as with serrated needle drivers ➔ ↑needle twisting Caution: larger needles will ruin small needle drivers ○ Larger, serrated jaws Ideal for larger needles and work on trunk Advantages: serrated jaws hold needles more securely (prevents twisting) Disadvantage: damages delicate needles, shreds small suturesForceps - name three types of forceps - how can you distinguish them? - what do bishop harmon forceps always have?■ Basics ○ Serrated forceps: easier to grab needle, but results in ↑tissue crush injury ○ Toothed forceps: harder to grasp needle, but handles tissue gently (↓crush injury) ○ Combination forceps: have both teeth as well as serrated platforms ➔ allows for gentle tissue handling and easier grasping of needle ■ Types ○ Adson: relatively large forceps; useful for trunk and extremities ○ Bishop-Harmon forceps: small, fine-tipped instruments; most useful for delicate tissues such as the eyelids; always have 3 holes in handles to make them lighter in weight and easier to grip ○ Jeweler's forceps: have very pointy ends; most useful for suture removalsurgical needles - name the three portions of the needle - Where should the needle be grasped? - What are the three types of needlesSurgical needles ■ Needle is composed of three parts: ○ Shank (swage): swaged portion that attaches to suture; weakest part of needle ➔ do NOT grasp here, it will bend or break the needle Size of suture track is determined by shank size, not suture size ○ Body: middle part; strongest portion of needle ➔ always grasp here with needle driver; comes in various curvatures (most common is 3/8 circle) ○ Tip: sharp tip that may be round (tapered) or cutting; minimize grasping of tip ➔ contact w/ other instruments quickly dulls the tip ■ Three types of needle tips: ○ Round (tapered): only the tip pierces tissue (no sharp edges along arc of needle); is less likely than cutting needles to tear tissues; used for deep soft tissues (fat and muscle); difficult to pass through skin ○ Cutting: triangular-shaped needle point; preferred for skin because it easily passes through tissue; two types: - Conventional cutting: cutting surface is on inner portion of needle arc; ↑risk of sutures tearing through wound edge (this is because the cutting edge of needle faces toward the wound edge) - Reverse cutting: cutting surface is on outer portion of needle arc; ↓risk of sutures tearing through wound edgecuticular suturing: Name the benefits and disadvantages to each type of stitch - simple interrupted - simple running - running locked - vertical mattress - horizontal mattress - pulley suture - running horizontal mattress - tip stitch - high low step off stitch• Cuticular/epidermal suturing ■ Simple interrupted: used for wounds under moderate to high tension; directing the needle away from the wound results in ↑eversion and less frequent sunken scars ■ Simple running: used for wounds under minimal tension; faster to place than interrupted sutures; ↑risk of wound dehiscence ■ Running locked sutures: provides hemostasis, but has risk of strangulation ■ Vertical mattress: strongly everts (Vertical = eVert) wound edges, eliminates dead space, and decreases wound edge tension ■ Horizontal mattress: provides hemostasis (Horizontal = Hemostasis), eliminates dead space, and decreases wound edge tension; significant strangulation risk ➔ do not use in poorly vascularized areas ■ Pulley suture: modified vertical mattress suture; used for wounds under high tension ■ Running horizontal mattress: same benefits as simple horizontal mattress, but is faster, provides ↑eversion, and ↓strangulation risk; improved outcomes relative to simple running sutures, but takes longer ■ Tip stitch: best stitch for flap and M-plasty tips; is a half-buried horizontal mattress suture ■ High-low (step-off stitch): used to correct imprecise dermal/subcuticular suturing, where one side of the wound edge is higher than the other ("step-off")subcuticular dermal suturing - simple buried - buried vertical mattress - set back suture (buried butterfly) - running subcuticular - purse string - Figure of 8 - pulley suture• Subcuticular/dermal suturing ■ Simple buried suture: traditional intradermal suture; results in minimal wound eversion and high rate of spitting sutures ■ Buried vertical mattress: has one exit point in the subcutaneous plane; everts tissue more than a simple buried suture ■ Set-back suture ("buried butterfly"): suture entry and exit points are both underneath the undermined wound surface; everts tissue maximally; results in ↓spitting sutures and ↑cosmetic outcomes than the buried vertical mattress technique ■ Running subcuticular: running sutures in superficial dermis, instead of along epidermal surface; primary advantage = lack of track marks; however, ↑rate of spitting sutures; typically used in combination w/ buried vertical mattress sutures ■ Purse-string: traditionally used to ↓wound size and ↓healing time, relative to second intention; a recent RCT study did not demonstrate any difference in cosmetic appearance or scar size, but there was a trend toward faster healing time ■ Pulley suture: buried (subcuticular) pulley suture is essentially just a series of two or more simple buried subcuticular sutures; primary advantage = permits wound closure under high tension; disadvantage = tissue strangulation ■ "Figure of 8": main suturing method used to tie off bleeding vessels- When should sutures be removed per area (risk of sutures remaining in place too long?) - Suspension sutures - Name the antibiotic suture coating -• Suture removal recommendations (largely anecdotal): head/neck ≤7 days, extremities/torso = 10 to 14 days; the longer the sutures remain in place ➔ ↓likelihood of dehiscence, but ↑cutaneous track-marks • Suspension sutures: anchor the overlying tissue to periosteum ➔ removes tension from leading edge of flaps; prevents distortion of a free margin (especially eyelid), also prevents flap "tenting" across a concavity • Suture coatings ■ Friction coatings: some multifilament sutures are coated with material to ↓friction ➔ more easily pulls through tissue ■ Antibiotic coatings: many sutures now contain antibiotics, chiefly triclosan; a recent meta-analysis demonstrated ↓surgery site infections relative to noncoated sutures • Barbed sutures ■ New, knot-less suturing method that is gaining popularity; barbs hold tissue in place; main benefits: tension is distributed evenly along entire course of wound, faster to use than traditional sutures; most common use = large wounds under ↑tension- Name the two categories of tissue adhesive - which one dries faster and which is more rigid? - disadvantages to standard cuticular sutures?• Tissue adhesives ■ Two categories: ○ Octyl: octyl cyanoacrylate (DermabondTM) ○ Butyl: butyl cyanoacrylate (LiquibandTM) and N-butyl 2-cyanoacylate (GluSealTM) Details: - Butyl types of cyanoacrylate dry faster than octyl type (30 vs 150 seconds); however, butyl types are more rigid - All are typically used in combination w/ traditional subcuticular sutures - ↑wound dehiscence rate and unable to achieve as much eversion (vs sutures)- Most absorbable sutures lose their tensile strength in what amount of time? - natural fibers and synthetic fibers and synthetic fibers are broken down via what? - suture absorption rate is increased by in what situations - What are the natural fibers? - between natural and synthetic fibers which is degraded faster and which is is more inflammatorySuture type (absorbable vs nonabsorbable) Absorbable sutures - Lose most of their tensile strength within 60 days Natural fibers: digested by proteolysis Synthetic fibers: broken down by hydrolysis - Most commonly used as "deep" sutures Rate of loss of tensile strength is different than rate of suture absorption!!! Tensile strength is lost long before suture is fully absorbed - ↑absorption rate in moist areas, febrile or protein-deficient patients Nonabsorbable sutures Maintains tensile strength for >60 days Most commonly used as superficial/epidermal sutures Suture material (absorbable; natural vs synthetic) Natural Derived from natural proteins (gut, silk) Degraded by proteolysis - ↑inflammatory reaction and are rapidly degraded Synthetic Synthetic copolymers Degraded by hydrolysis - ↓inflammatory reaction and are slowly degradedAdvantages and disadvantages of monofilament vs multifilament suturesConfiguration (monofilament vs multifilament [braided]) Monofilament Comprised of a single filament - Advantages: slide easily through tissue (because of ↓COF), harbors less bacteria than braided sutures (because of ↓capillarity), and low-minimal inflammatory reaction - Disadvantages: ↓knot security (because of ↑memory and ↓COF); poor "ease of handling" (because of ↓pliability and ↑memory) Multifilament (braided) Comprised of multiple small filaments braided together - Advantages: ↑ease of handling (because of ↑pliability and ↓memory), ↑strength, and ↑knot security (because of ↑COF and ↓memory) - Disadvantages: ↑bacterial infections (because of ↑capillarity), and ↑inflammatory reactionCapillarity: meaning, which suture type has more? Are synthetic or natural sutures stronger? A knoted suture has what % of its original tensile strength? Coeficient of friction↑capillarity ➔ suture wicks more fluid from wound surface into wound (conduit for bacteria) Multifilament sutures have ↑capillarity ➔ ↑infection More zeroes = smaller suture diameter (6-0 suture is smaller than 5-0) Inherent strength of the material also affects USP size (Prolene is inherently stronger than gut ➔ 4-0 Prolene will be smaller in diameter than 4-0 gut) Synthetic sutures are generally stronger than natural materials A suture that has been knotted only has 1/3 of its original tensile strength ↓COF ➔ ↓knot stability (slippery) Polypropylene (Prolene) has a very low COF ➔ easily slides through tissue ➔ ideal for subcuticular sutures, but requires more throws to secure knot Braided sutures have ↑COF ➔ ↑knot stabilityHow does memory relate to knot security and ease of handling What is suture plasticity what is suture eleasticityBraided sutures have ↑pliability ➔ easier to tie knots/↑ease of handling Pliability and memory are the two main determinants of "ease of handling" Is one of two main determinants of knot security (other is COF) Is one of two main determinants of "ease of handling" (other is pliability) ↑memory ➔ ↓knot security and ↓ease of handling Monofilament sutures have ↑memory relative to braided sutures ↑plasticity allows suture to stretch to accommodate postoperative swelling without cutting into tissue (Prolene has ↑plasticity than nylon) ↑elasticity is an ideal suture property: elasticity allows suture to stretch to accommodate swelling, and later, resume its original shape ➔ keeps wound edges approximated after edema has resolved Polybutester (Novafil) and poliglecaprone-25 have ↑elasticity ➔ good for swollen tissues Knot security: Higher with multifilament sutures Directly proportional to COF Inversely related to memorycommonly used sutures - Monocryl (name what type of suture, highest initial what? how inflammatory) - PDS (name, what type of suture, how long does it last?) - Silk (What type of suture, used where, second highest what?Polyglecaprone-25 (MonocrylTM) Monofilament 7-10d 90-120 Good Good Minimal ↑knot security and ease of handling relative to other monofilaments; least inflammatory; highest initial tensile strength Polydioxanone (PDS IITM) Monofilament 30-50d 180-240d Poor Poor Low Longest lasting absorbable suture ➔ good for high-tension closures Silk Braided Gold standard Good High Used on mucosal surfaces Best handling of any suture Second highest tissue reactivity (#1 is plain gut)Prolene (name, what type of filament, describe inflamation, ideal for what?) Polyester (type of suture, describe the tensile strength, used where, similar to what other suture type but is less inflammatoryPolypropylene (ProleneTM, SurgileneTM) Monofilament Good to fair Poor Least Least inflammatory nonabsorbable suture; has extremely low COF ➔ ideal for running subcuticular suturing Stretches with swelling, rather than cutting into tissue Polyester (EthibondTM, DacronTM, MersileneTM) Braided Very good Good Minimal Highest tensile strength of any nonabsorbable suture (excluding stainless steel) Used on mucosal surfaces Similar to silk, but less inflammatoryTissue reactivity - Absorbable - nonabsorbable Initial tensile strength - absorbable - non absorbableTissue reactivity Absorbable: Surgical gut > Polyglycolic acid, polyglactin 910, and lactomer > polydioxanone > polyglyconate = poliglecaprone 25 nonabsorbable: Silk > Nylon > Polyester, polybutester > polypropylene (least) Initial tensile strength - Absorbable: Poliglecaprone 25 > polyglyconate > polydioxanone > polyglactin 910, lactomer > polyglycolic acid > surgical gut - nonabsorbable: Stainless steel (#1 overall) > polyester (#1 nonmetal suture) > nylon, polybutester > polypropylene > silkAfferent sensory fibers - name the three types - which are myelinated, what type of sensation does each project• Three major categories of afferent sensory fibers: ■ C fibers: small diameter, unmyelinated nociceptors; transmit diffuse, dull, and aching pain ■ Aδ fibers: medium diameter, lightly myelinated fibers; transmit sharp, localized pain and temperature ■ Aβ fibers: fast-conducting, large-diameter, myelinated fibers; detect vibration and light pressure; large Aβ fibers respond slowly to local anesthetic ➔ patients continue to "feel something, but not pain" after injectionLocal anesthetics - mechanism of action Amides (metabolized how?, are allergic reactions common? what causes them? contraindication) Esters (metabolized how?, common cause of allergy, contraindications?• Local anesthetics (Table 8-10) ■ Mechanism: reversible inhibition of sodium ion influx ➔ blocks nerve conduction ■ Chemical structure ○ Aromatic end - lipophilic, affects potency and duration of action ○ Intermediate chain - linkage portion Amides (most commonly used) - Metabolized via CYP 3A4 system in liver Esters vs amides: "two 'I's' = amIde" Allergic reactions are rare; typically occur as a result of methylparaben preservative, not anesthetic (if occurs, switch to preservative- free lidocaine) Contraindications: end-stage liver disease Esters Metabolized via pseudocholinesterases in plasma; renally excreted Less stable in solution Frequent allergic reactions to PABA metabolite - Cross-reacts with multiple contact allergens (Mnemonic "PPPESTAA"): Paraphenylenediamine (PPD), PABA, Para-aminosalicylic acid, Ethylenediamine, Sulfonamides, Thiazides, Anesthetics (esters), Azo dyes Contraindications: allergy to PABA or cross- reacting substances, pseudocholinesterase deficiency, and renal insufficiencyAmides: - name some amides, which is the anesthetic of choice for pregnancy - prilocaine has a risk of what? - which has the longest duration of action, risks of bupivicaine? Esters: - name twoAmides: - Lidocaine: fastest onset and anesthetic of choice for pregnant females - Mepivacane: - Prilocaine: Risk of methemoglobinemia (↑risk with G6PD deficiency and in children <1 y.o.) Component of topical EMLA - Bupivicaine: Longest duration of action, when combined with epinephrine (up to 8 hours) Most common use: added to lidocaine for big Mohs cases to provide long-lasting anesthesia Highest risk of cardiac toxicity! Risk of fetal bradycardia Esters: - Procaine - tetracaineAdditives to local anesthetics 1) Epi (name typical dilutions , mechanism, advantages, disadvantages, contraindications, cautions) - How long does the full vasoconstrictive effect take? 2) Sodium Bicarb (Mechanism, advantages, disadvantages)■ Additives to local anesthetics ○ Epinephrine (1:200000 equally as effective, w/ ↓toxicity than 1:100000) Mechanism: vasoconstriction ➔ localization of anesthetic - Advantages: ↑safety and duration of anesthetic (because less diffusion and absorption), ↓bleeding (full vasoconstrictive effect takes 7-15 minutes) - Disadvantages: ↓uterine blood flow (pregnancy category C) Contraindications: pheochromocytoma and uncontrolled hyperthyroidism Caution with: pregnancy (shown to be safe if dilute epinephrine to 1:300000), severe CV disease, HTN, glaucoma, and drugs (β-blockers, TCAs, and MAO-I) ○ Sodium bicarbonate 8.5% (1 mL per 10 mL of 1% lidocaine) Mechanism: bicarbonate raises pH to near- physiologic levels ➔ majority of anesthetic remains neutral/uncharged ➔ more rapidly crosses nerve membranes - Advantages: ↑speed of onset and ↓injection pain (as a result of physiologic pH) - Disadvantages: ↓shelf-life, because of epinephrine degradation (must use within 1 week)Lidocaine - anesthetic of choice for whom? - most commonly used concentrations. How many mg/ml - max doses of with and without epi and in peds - what is the max dose of tumescent lidocaine? pregnancy category?○ Most commonly used local anesthetic; anesthetic of choice for pregnant women ○ Most commonly used concentrations: 1% (10 mg/mL), 2% (20 mg/mL), and 0.1% tumescent (1 mg/mL) ○ Must know the maximum doses! Without epinephrine = 4.5-5 mg/kg (35 mL of 1% lidocaine in 70 kg patient) Pediatric = 1.2-2 mg/kg (2.4 mL of 1% lidocaine in a 20 kg patient) With epinephrine = 7 mg/kg (49 mL of 1% lidocaine in 70 kg patient) Pediatric = 3-4.5 mg/kg (6 mL of 1% lidocaine in a 20 kg patient) Tumescent anesthesia = 55 mg/kg 10-fold dilution of standard 1% lidocaine with 1:100000 epinephrine (= 0.1% lidocaine with 1:1 000000 epinephrine) - Advantages: ↓bleeding, ↑duration of anesthesia, and avoids complications a/w general surgery (↓morbidity and mortality) ○ Caution w/ end-stage liver disease ➔ ↑risk of lidocaine toxicity (metabolized by liver) ○ Pregnancy class B, lactation safeSymptoms of lidocaine overdose - mild, moderate, severe, life threatening - easiest way to distinguish between vasovagal, epi reaction, and anaphylaxis is what? - True allergy reactions are typically caused by what?• Must know the presentations of the various adverse reactions to local anesthetics! ■ Mnemonic: lidocaine overdose stages loosely resemble alcohol overdose: ○ Mild (~"Happily buzzed and tingly feeling"): restlessness, euphoria, talkativeness, lightheadedness, "funny tingling" around mouth and hands, metallic taste, and circumoral numbness ○ Moderate (~"Hammered! Can't hear or speak well"): nausea, vomiting, psychosis, tinnitus, muscle twitching/tremors, blurred vision, slurred speech, and confusion ○ Severe (~"Severe alcohol poisoning"): seizures and cardiopulmonary depression ○ Life-threatening: coma and cardiopulmonary arrest ■ Easiest way to distinguish between vasovagal (most common), epinephrine reaction, and anaphylaxis (most severe) is to compare BP and HR • True allergies to local anesthetic are rare! ■ More commonly, patients are sensitive to the epinephrine contained within them ■ True "allergies" are usually as a result of parabens, para-amino benzoic acid (PABA), or metabisulfide preservatives ■ Amide anesthetics do not cross-react w/ ester anestheticschlorhexidine should never be used around what? - chlorhexidine bottles can become colonized with what? Alcohol: - mechanism of action - what is the optimum concentration of alcohol? - onset, spectrum, inactive against what?■ Important considerations: ○ Alcohol: flammable ➔ may lead to fires, especially in hair baring areas ○ Chlorhexidine: should never be used around the eye (➔ severe corneal damage) or ears (ototoxic). - Serratia may colonize chlorhexidine bottles ➔ infection Alcohol (isopropyl and ethanol) - Denatures cell walls; 100% alcohol is less effective than 70% (optimal strength) - Very rapid onset (fastest) - Very broad spectrum: G(+), G(−), mycobacteria, and many viruses - Inactive against spores, protozoan oocysts, and certain nonenveloped viruses; not effective for soiled hands - None Flammable ➔ caution w/ electrosurgery and lasersChlorhexidine - mechanism of action, spectrum, inactive against what? - #1 for what? - avoid around what? Iodine - Mechanism of action - Spectrum - inactivated by what? - when is it activeChlorhexidine (2%-4%) - Disrupts cell membranes - Rapid onset - Broad spectrum: G(+), G(−), viruses, fungi, and mycobacteria; not inactivated by organics (blood and sputum) - Inactive against spores; ototoxicity, keratitis, and conjunctivitis #1 overall for residual activity (>6 hours; remains bound to stratum corneum) - Longest acting - Often avoided around eyes/ears Iodine and iodophors - Oxidation ➔ disruption of protein synthesis and cell membranes - Rapid Very broad spectrum: G(+), G(−), bacterial spores, mycobacteria, viruses, and fungi - Skin irritation and discoloration (less w/ iodophors); inactivated by blood and sputum - Minimal Must wait for it to dry to be effectiveElectrosurgery vs electrocautery - electrosurgery uses what type of current, what does this prevent - electrosurgery relies on what? - what are the four types of of electrosurgery - How is electrocautery different from electrosurgery?• Electrocautery and electrosurgery often incorrectly used interchangeably ■ Electrosurgery: high-frequency alternating current to conduct energy via a cold-tipped electrode ○ High-frequency alternating current prevents the depolarization of muscles and nerves ○ Employs an unheated electrode and relies on the high resistance of human tissue, a poor electrical conductor, to halt the flow of current and to convert electrical energy into thermal energy, resulting in hemostasis via heat-induced tissue destruction ○ Types: electrosection, electrocoagulation, electrodesiccation, and electrofulguration ■ Electrocautery: direct application of heat to tissue via a hot-tipped electrode generated by a direct current ○ There is no current flowing through the patient and hemostasis is achieved by the direct application of heat (vs electrosurgery where an alternating current is present)Monoterminal vs biterminal devices - what is the difference between the two - which forms of electrosurgery are mono and bi-terminal - what is the electrical difference between the mono and bi-terminal modalitiesMonoterminal and biterminal devices • Monoterminal and biterminal: refers to the absence or presence of a grounding electrode • Monoterminal circuits (electrodesiccation and electrofulguration) employ an active electrode without a grounding pad; because there is no dispersive electrode to dissipate the accumulated current, higher voltages are needed to reach the desired level of effective tissue destruction; only electrical difference between electrofulguration and electrodesiccation is that the probe does not directly contact the skin in electrofulguration • Biterminal circuits (electrocoagulation and electrosection) always employ a dispersive electrode to recycle current ■ Current travels through the body from the active electrode to the dispersive electrode (grounding pad or biterminal forceps) and exits via the latter; dispersive electrodes provide an outlet of return of current to the electrosurgical device, permitting increased amperage and reduced voltage; only electrical difference between electrocoagulation and electrosection is the degree of dampingElectrocautery - how is it distinguished from electrosurgery - safe in what patients> electrodessication - what type of device - describe the amperage and voltageElectrocautery • Electrocautery is distinguished from electrosurgery by its absence of alternating current • Direct current in electrocautery supplies energy to the device's tip ➔ generates heat ➔ red-hot tip is applied directly to tissue • Current does not pass through the patient; destruction is achieved solely by heat conducted to the tissue • Safe in patients w/ implantable cardioverter-defibrillators (ICDs) and pacemakers because of the absence of current traveling through the body • Additional advantages: portable and effective in a wet field Electrodesiccation • Monoterminal device • Causes superficial ablation when a probe is placed in direct contact w/ tissue • When the probe directly contacts tissue, this low-amperage high-voltage system slowly heats tissue ➔ results in water loss ➔ dehydration and superficial mummification, but no significant protein denaturationElectrofulguration - mono or biterminal, how is it different from electrodessication - describe the amperage and voltage - what happens to the tissue? why is this beneficial Electrocoagulation - what kind of device - describe the amperage and voltage - how does it compare to electro dessication Electrosection - what type of device, amperage and voltage - how does it compare to electrocoagulationElectrofulguration • Monoterminal device (e.g., hyfrecator) • Causes surface carbonization when electrical probe is held at a distance from tissue (no direct contact) • When the probe is held at a distance, this low-amperage high-voltage system produces an ionized current between the probe and tissue ("spark gap") ➔ superficial tissue ablation occurs, but the underlying tissue is protected from thermal heat spread by superficial carbonization • Similar to electrodesiccation in most respects, with the exception that the spark gap and resultant superficial carbonization result in more limited, superficial tissue destruction Electrocoagulation • Form of electrosurgery using a biterminal device • High-amperage low-voltage form of electrosurgery; utilizes a moderately damped waveform • Tissue is ablated by direct contact with probe ➔ slow cellular heating ➔ intracellular fluid evaporation, coagulum formation, and resultant protein denaturation • ↑current (amperage) penetrates more deeply than in electrodesiccation ➔ ↑potential for deep tissue destruction and hemostasis Electrosection • Like electrocoagulation, electrosection is a high- amperage low-voltage method of electrosurgery using a biterminal device • In contrast to electrocoagulation, electrosection employs an undamped waveform for the purpose of pure cutting, as with a blade • If used on a "blended mode" with electrocoagulation ➔ provides a mixture of hemostasis and cutting- Are ICDs or pacemakers more susceptible to electromagnetic signals? - what can be used to eliminate the risk of interference with pacemakers/ICDs - Which form has the highest risk of tripping an implantable device? - forms of electrosurgery should not be used within what distance of an implantable device? - What can be done for non-cardiac implantable devicesImplantable electronic devices • Pacemakers and ICDs ■ Most modern (1980s and on) implantable devices are resistant to external electromagnetic signals; however, there remains a theoretical risk of disturbance ■ ICDs are more sensitive than pacemakers to electromagnetic interference (because of the presence of sensing circuits) ■ Electrocautery can be used to eliminate 100% of the risk of interference ■ Electrosurgery using biterminal (often erroneously referred to as "bipolar") forceps (most common way to address this issue) is also less likely to cause electromagnetic interference ■ Magnet devices are often used during electrosurgery ➔ pacer stops paying attention to all electrical signals ➔ paces at a preset rate ■ In cases in which biterminal forceps cannot be used or are unavailable, caution should be taken: ○ Direct the path of current away from implantable devices ○ Do not position implantable devices between the active and dispersive electrodes ○ Use short bursts of energy (<5 seconds and spaced >5 seconds apart) ○ Use lowest effective power settings ○ Avoid electrosection (highest risk!) ○ Do not use within 5 cm of implantable device ○ Have a crash cart and ACLS-trained staff ready ■ In cases of uncertainty ➔ cardiology consultation • Noncardiac implanted electronic devices ■ Examples: deep brain stimulators, spinal cord stimulators, vagal and phrenic nerve stimulators, gastric stimulators, and cochlear implants ■ In contrast to ICDs, patients are usually equipped with an external remote control to power these devices offMechanism of action of of cryosurgery - what is the boiling point of liquid nitrogen - what is the temperature of cell death for melanocytes, keratinocytes, fibroblast, benign , malignant (which is the most sensitive? which is the least sensitive?) - what is the optimal freezing technique, Why?• Application of low temperature substances ➔ cellular injury, sloughing of damaged tissue, and subsequent healing • Mechanism of action: ■ Extracellular dehydration: results from formation of ice crystals first in the extracellular space causing an extracellular hyperosmotic gradient that dehydrates the adjacent cells ■ Membrane rupture: occurs from continued freezing, which causes intracellular ice crystal formation and eventual membrane rupture ■ Vasoconstriction: results from initial freezing ➔ causes further damage through anoxia ■ Vasodilation: after thawing, compensatory vasodilation releases harmful free radicals into affected tissue ➔ further tissue damage • Specific cryogens: ■ Liquid nitrogen (boiling point: −196°C): most common ■ Solid carbon dioxide (boiling point: −79°C): occasionally used for chemical peels • Temperature required for cell death (boards favorite!): ■ By cell type: ○ Melanocytes (most sensitive): −5°C ○ Keratinocytes: −20°C to -30°C ○ Fibroblasts (least sensitive): −35°C to −40°C ■ Benign vs malignant ○ Benign: −25°C ○ Malignant: −50°C • Optimal freezing technique = rapid freezing + slow thawing (favors intracellular ice formation) • Delivery techniques ■ Open technique: most commonly performed; liquid nitrogen is released through tips, needles, cannulas, or cones ■ Chamber technique: modification of "open technique"; typically used only for malignancies; cryogen is released into a chamber ➔ turbulence within the chamber ➔ lower temperatures achieved, and in shorter amount of time than w/ open technique ■ Closed technique: uses a probe to deliver the thermal insult; attached directly to the cryogen line and is a closed system (thus its name)- apical angles of each excision should be what degree? - ideal length:width ratio - Benefits and uses of the following closures - crescent, M plasty, S plasty, - Full lip wedge, can be used for what sized defects, in what order are the layers closed? - what are the causes of standing cones? - What is the difference between simple and layered closure? - Optimal undermining planes for: cheek, eyebrow, ear, eyelid• Indications: biopsy, removal of benign and malignant lesions, and scar revision • Design: closure of a circle results in large standing cones on each side of the closed wound ➔ therefore, most excisions are executed in a fusiform fashion ■ Apical angles: angles at either end of the excision; ideally ≤30° in order to avoid formation of standing cones ■ Length:width ratio should be ≥3:1 ■ Generally, place excisions parallel to relaxed skin tension lines • Variations: ■ Crescent excision: when one side of excision is designed longer than the other, a curved/crescent shape will result; common uses: sites where relaxed skin tension lines are curvilinear (cheek and chin) ■ M-plasty (Fig. 8-14): used to shorten length of excision such that the incision does not extend into an undesired location; common uses: near free margins (perioral and periocular regions) ■ S-plasty ("lazy S"): ↑total length of scar, but the linear distance between two apices remains same as linear closure; redistributes tension along different vectors ➔ ↓tension in central portion of scar ➔ ↓risk of centrally depressed scar, ↓dehiscence, and ↓contraction of scar; common uses: convex surfaces (forearm and shin) and excisions that cross over a joint (elbow and knee) ■ Lip wedge excision: full-thickness excision of the lip with layered repair; may be used to repair defects up to 1/3 of the length of lower lip; must mark vermillion border before closure ➔ ensures precise realignment; close lip in layered fashion in the following order (high yield!): ○ Submucosal layer: use silk or polyglactin 910, bury knots away from oral cavity ○ Orbicularis oris muscle: use polyglactin 910; critical step ➔ maintains competence of oral sphincter ○ Dermis and subcutaneous tissue: use polyglactin 910; start by reapproximating vermillion-cutaneous border ○ Epidermis: use nylon w/ hyper-eversion to prevent depressed scar • Standing cones ("dog ears"): ■ Causes: apical angles that are too wide (>30°), length:width ratio <3:1, unequal lengths on each side of wound, convex surfaces, and insufficient undermining at wound apices ■ Repair options ("dog ear repairs"): ○ Extending incision: ↑excision length allows for redistribution of excess skin ○ M-plasty: removes standing cones ○ Rule of halves: standing cone is redistributed along entire excision length by "halving" it throughout ○ Excision of a Burow's triangle: a triangle of tissue removed from the side of the wound with the standing cone • Closure types: ■ Simple closure: one layer of sutures (epidermal closure only) ■ Layered closure: two or more layers (epidermal + dermal, SQ or fascia) of sutures ➔ ↓tension on wound edges, ↓dead space (results in ↓hematomas and ↓seromas), and improved cosmetic outcomes • Undermining planes (Boards Favorite!): ■ Trunk/extremities: mid-deep fat (for small or superficial defects), or just above deep fascia (larger excisions and invasive melanomas) ■ Face: undermining in superficial subcutaneous plane (superficial to SMAS); preserves motor nerves, which are all deep to SMAS ○ However, optimal undermining planes vary by facial subunit ■ Optimal undermining planes by facial subunit: ○ Cheek: mid subcutaneous plane ➔ avoids transecting parotid duct, buccal and zygomatic branches of CN7, and vascular structures ○ Ear: given the near lack of adipose tissue, dissection is always just above perichondrium ○ Eyebrow: subcutis, deep to hair bulbs ➔ minimizes eyebrow hair loss ○ Eyelid: immediately above orbicularis oculi muscle (because there is minimal subcutaneous tissue)Optimal undermining planes continued - forehead, lateral neck, lip, mandible, nose, scalp, temple - Wound strength at 1 week, 2 weeks, 1 month, 1 year○ Forehead: deep subcutaneous plane, just above frontalis (small, superficial wounds); occasionally undermine in subgaleal plane (large or deep wounds) ➔ superficial SQ undermining preserves sensory nerves; subgaleal plane is avascular ○ Lateral neck: superficial subcutaneous plane, above spinal accessory nerve ➔ avoids Erb's point ○ Lip: Immediately above orbicularis oris muscle ➔ avoids cutting into vascular orbicularis muscle and branches of labial artery ○ Mandible: superficial subcutaneous plane, above marginal mandibular nerve ○ Nose: submuscular fascia/periosteum/ perichondrium (deep to SMAS/nasalis muscle) ➔ relatively avascular plane ○ Scalp: subgaleal ➔ avascular plane ○ Temple: superficial subcutaneous plane ➔ avoids transection of temporal branch of facial nerve and temporal artery • Wound healing (see Basic Science chapter) • Wound strength following surgery never returns to 100%; dehiscence risk is highest at time of suture removal (1 to 2 weeks) ■ 1 week = 5% ■ 2 weeks = <10% ■ 1 month = 40% ■ 1 year and beyond = 80% (maximum strength)Surgical Margins - Melanoma - BCC - SCC - DFSP What are high risk features• Surgical margins: ■ Melanoma: ○ Melanoma in situ ➔ 0.5 cm-1 cm ○ Breslow depth <1 mm ➔ 1 cm WLE to deep fat or fascia (variable) ○ Breslow depth 1-2 mm ➔ 1-2 cm WLE to fascia ○ Breslow depth >2 mm ➔ 2 cm WLE to fascia ■ BCC: 4 mm margins for most tumors; 0.6-1 cm margins or Mohs for high-risk BCC ○ High-risk BCC (any one feature): >2 cm diameter on any site, >1 cm diameter on face/neck/scalp, >0.6 cm diameter on high-risk area ("H-zone of face"), poorly defined and aggressive histology (infiltrative, morpheaform, micronodular, and basosquamous), recurrent, at site of prior radiation/scar, perineural/perivascular invasion, and immunosuppressed status (CLL, HIV, or hematologic malignancy) ■ SCC: 4 mm margins adequate for most low-risk SCC; high-risk SCC is best managed with 0.6 cm margins or Mohs ■ DFSP: 2-3 cm margins extending at least to fascia is recommended, but is a/w ↑recurrence rate relative to MohsName the essential steps of mohs - scalpel should be held at what angle?• Essentials steps of Mohs technique: ■ Clinically apparent residual tumor/biopsy site is debulked with curette or scalpel ■ Beveled excision (scalpel held at 45° angle) of tumor plus a small (1-2 mm) margin of normal-appearing skin ■ Hash marks ("notches") are placed on excision specimen and surrounding nonexcised skin to assist w/ orientation ■ Excised specimen may be divided into two or more pieces (optional) ■ Excised specimen is inked with two or more colors ■ Histotechnician flattens tissue to ensure that the epidermis lies in the same plane as the deep tissue ➔ allows for horizontal processing of slides (stain = H&E or Toluidine blue) ➔ enables simultaneous microscopic evaluation of superficial and deep margins- what is the key stitch definition? - what is an axial pattern flab? (name the artery associated with the following flaps (paramedian forehead, dorsal nasal, abbe cross lip - What are random pattern flaps?■ Key stitch: critical initial stitch required to move the flap onto the primary defect ■ Axial pattern flap: flaps based on a named vessel ➔ most reliable; includes paramedian forehead flap (supratrochlear artery), dorsal nasal rotation "Rieger" flap (angular artery), and Abbe cross-lip flap (labial artery) ■ Random pattern flap: flaps with unnamed musculocutaneous arteries within pedicle; elevated portion of flap is perfused by anastomotic subdermal and dermal vascular plexuses; includes all flaps not listed aboveAdvancement flap - mechanics, goal, disadvantages Rotation Flap - mechanics, goal, disadvantages, common use○ Advancement flap (Table 8-16): Mechanics: does not redirect primary tension vector Goal: redistribute Burow's triangle away from free margins (eyelid, ear, lip, and alar rim) ➔ move to a more functionally/cosmetically desirable location Disadvantages: limited by degree of elasticity of surrounding tissue ➔ suboptimal for large defects that lack abundant adjacent tissue reservoir/laxity ○ Rotation flap (Table 8-17): Mechanics: redirects primary tension vector along an arc adjacent to primary surgical defect while simultaneously creating a secondary defect along the flap arc Goal: take advantage of tissue reservoir/laxity at a distance from primary defect Disadvantages: there is a functional loss of flap length and height when flap is rotated onto defect ➔ length of flap arc must be much longer than width of primary defect and height of flap must be taller than height of primary defect; is a heavy flap and prone to causing unwanted secondary tension vectors ➔ may result in distortion of free margins (ectropion) if not carefully executed ➔ may require tacking sutures to periosteum to minimize risk Main uses: large defects on medial cheek; large defects on inelastic skin (scalp); areas w/ curved RSTLs (chin and along mental crease); redistribute tension away from free margins (lower eyelid, nasal tip, and upper lip)transposition flap - mechanics - goal, disadvantage interpolation flap - mechanics - goal○ Transposition (single stage) (Table 8-18) Mechanics: redirects primary tension vector onto donor site ➔ results in loose flap of skin that can be "plopped onto" primary defect ➔ primary defect closed under minimal to no tension Goal: utilize nearby tissue reservoirs in order to close defects at sites that have minimal inherent laxity Disadvantages: prone to pincushioning/"trapdooring" (➔ must widely undermine to prevent); technically challenging ○ "Interpolation" (two stage transposition) flaps (Table 8-19) Mechanics: same as single-stage transposition flaps, but retains thick vascular pedicle (either random pattern or axial) to ↑blood flow ➔ allows for ↑↑↑flap length:width ratio (>4:1 maximum ratio seen with most other flaps), and coverage of very large defects; pedicle typically divided and inset at 3 weeks Goal: utilize nearby tissue reservoirs in order to close defects at sites that have minimal inherent laxity Main uses: large defects on nose, large helical rim defects, and large lip defectsIsland pedicle flap - aka - ideal length/width - key stitch - how much of the pedicle must remain in tact - disadvantagesIsland pedicle/"kite" flap (renamed V ➔ Y advancement) - Unlike other advancement flaps, area under flap body is not undermined (serves as random-pattern pedicle); periphery is undermined widely, then V-shaped island w/ pedicle is advanced onto defect; ideal length:width ratio ≤4:1; key stitch: connects midpoint of leading edge of flap to midpoint of defect's wound edge Small defects on nasal tip Small, deep alar defects (shark IPF) Small defects on medial upper cutaneous lip Medium to large defects on lateral upper cutaneous lip Large defects on medial cheek or nasofacial sulcus Lower eyelid defects Repair of ectropion In reality, a portion of pedicle must be undermined to allow for movement, but must ensure that ≥40% of pedicle remains intact - Disadvantages: triangular-shaped scar (often prominent); trapdoor effectMucosal advancement flap - undermine where unilateral rotation - two examples, how are they different, what are they used for.Mucosal advancement - Essentially a linear flap of lip mucosa; undermine deep to minor salivary glands, but superficial to orbicularis muscle; undermine to gingival sulcus; flap is advanced onto vermillion defect Vermillion lip Lip numbness develops in most, but improves over time Unilateral rotation, Mustarde/Tenzel variant Laterally based rotation flap of cheek/temple; Mustarde flaps utilize entire cheek/temple reservoir; Tenzel flaps are smaller (partial- cheek) Mustarde: larger lower lid defects (≥50%) Tenzel: smaller, partial thickness defects of mid to lateral lower lid (<50% of lid) Tacking sutures to lateral orbital rim periosteum ➔ ↓ectropion riskRieger flat, axial flap - what is the difference - where do you undermine - maximal points of pivotal restraint - DisadvantagesUnilateral rotation: - Rieger variant (dorsal nasal rotation, Hatchet flap, and glabellar turn-down) - Axial flap (angular artery) w/ back- cut in glabella; - undermine just above perichondrium; - maximal points of pivotal restraint = medial canthal tendon, nasofacial sulcus Medium to large (up to 2.5 cm) midline defects on lower 2/3 of nose (tip/supratip) Disadvantages: transposition of thick glabellar skin onto medial canthus (number one concern), long incision lines, potential "pig-nose" deformity (as a result of inadequate undermining)Rhombic Flap -classic design - what is closed first? - used for what areas - final suture line looks like what?Rhombic Classic design (Limberg flap: parallelogram- shaped flap w/ two 60° angles and two 120° angles; flap takes off from defect at 90° angle; Burow's triangle removed a pivot point; secondary defect is closed first (key stitch) Medial and lateral canthi Cheek Upper lateral 1/3 of nose Perioral Final suture line looks like a question mark Eight rhombic flaps possible for any rhombic-shaped defect DuFourmental and Webster modifications: ↓angle of flap tip ➔ shorter arc of rotation ➔ easier to close secondary defect, ↑tension sharing between 1° and 2° defect, ↓reorientation of tension vectors, and ↑risk of ischemia (as a result of a narrower pedicle)Bilobed flap - used where - primary lobe diameter, secondary lobe diameter - undermine where? - order of closure and the key stitchBilobed transposition flaps (Zitelli modification) - Multilobed transposition flap that redistributes tension to areas of greater tissue laxity (e.g., nasal dorsum); tension is shared between all lobes; - 1° lobe diameter = primary defect diameter; 2° lobe diameter = 1° lobe diameter (or slightly smaller); flap - takeoff point = midpoint of defect at a 45° angle; angle between 1° and 2° lobe also = 45° ➔ flap has overall angle of 90°; remove standing cone at pivot point; - undermine flap in submuscular plane to nasofacial sulcus to achieve adequate movement; - order of closure = tertiary defect (2° lobe donor site; key stitch)➔ secondary defect (1° lobe donor site) ➔ primary defect closed last Distal 1/3 of nose May use as many lobes as necessary (trilobe, tetralobe) to reach a tissue reservoir where tension will not cause distortion - Risk of pincushioning (trapdoor) ➔ may be because of an oversized flap, insufficient undermining, ↑bulkiness on underside of flap, flap lympedema (self-resolves), peripheral contraction (↑risk w/ rounded flaps), or insufficient tacking of flap to wound base Original bilobed flap design was inferior to Zitelli's: used 180° overall angle (vs 90°) and did not remove standing cone at pivot point ➔ ↑pincushioning of 1° lobe, ↑standing cone at pivot pointBanner transposition flap - describe the shape of theseBanner transposition flap - Long, narrow transposition flaps w/ high length:width ratio (3:1-5:1); flap is raised along RSTLs and transposed 90° (or more) onto primary defect Upper helical rim Medial canthus and nasal bridge (glabellar banner) Lateral lower lid (upper lid skin is transposed) Medial lower lid (banner flap from nasofacial sulcus) - As a result of a narrow pedicle, must ensure flap has reliable/robust blood supply to prevent necrosis Prone to pincushioning (trapdoor) effect ➔ must undermine recipient site widely, undersize flap or deepen recipient bed, and use tacking sutures to ↓dead space between flap and recipient siteNasolabial/melolabial transposition flapNasolabial/ melolabial transposition flap Variant of banner flap w/ 60° angle of transposition; tack pivot point to piriform aperature (near junction of lateral ala/isthmus of upper lip); must thin distal portion of flap extensively Medium-sized, deep defects of nasal ala Disadvantages: blunting of alar crease (almost all cases), pincushioning ➔ minimized w/ tacking sutures, flap thinning, and wide undermining of recipient site Many cases require revision Spear flap (variant): used for full-thickness alar defects; same general design, but flap is folded on itself to provide internal nasal lining + external coverageZ plasty transposition flap - primarily used for what? - what happens as you increased the angle size? - Describe how much each angle increases the length of a scarZ-plasty Transposition flap - primarily used for lengthening a contracted scar and redirecting tension; may use various angles: - ↑angle size ➔ ↑length gain, and ↑reorientation of tension 30° angle ➔ 25% ↑length and 40° tension reorientation 45° angle ➔ 50% ↑length and 65° tension reorientation 60° angle ➔ 75% ↑length and 90° tension reorientationParamedian forehead flap - what kind of flap - based on what artery? - maximum length of flap? - where is the pedicle positioned? what is the ideal pedicle width? - When is the pedicle divided?Paramedian forehead flap - Axial flap based on supratrochlear artery; - maximum length of flap = distance between orbital rim to frontal hairline (if longer, will transplant hair onto nose); pedicle positioned on opposite side as main portion of nasal defect; pedicle oriented in vertical fashion, arising at medial eyebrow; ideal pedicle width = 1.0 - 1.5 cm; flap body elevated from cephalad to caudad in a plane just above periosteum; flap tip must be extensively thinned before suturing to nasal tip; pedicle is divided and inset at 3 weeks Large nasal defects Pedicle too narrow ➔ fails to incorporate artery ➔ ischemia Pedicle too wide ➔ kinking of artery ➔ ischemia and ↓rotational abilityAbbe lip switch axial - based on what artery? - when is the pedicle divided and inset? - used for defects where and how big?Abbe' lip switch Axial flap based on labial artery; transfers both mucosa and orbicularis oris muscle to recipient site; pedicle divided and inset at 3 weeks Large (>1/3 of lip), full- thickness defects of upper or lower lip Most commonly used for upper lip defects, because defects involving up to 1/3 of lower lip can be repaired via lip wedge Risk of microstomia and oral incompetence Nasolabial/ melolabial interpolation flap Random pattern flap perfused by small perforators of angular artery; similar in design to single-stage nasolabial transposition flap, but retains a thick vascular pedicle; extensively debulk flap tip before suturing onto primary defect; pedicle divided and inset at 3 weeks Nasal ala (number one use) Large defects of upper cutaneous lip Does not blunt alar crease = main advantage over single- stage transpositionFull thickness skin graft - comprised of what? - Primary goal - advantages, disadvantages - when you harvest the graft, how large should the graft be? - should these graft be defatted?■ Full thickness skin graft (FTSG): ○ Comprised of epidermis and full-thickness dermis ○ Primary goal: match donor skin w/ recipient site based on skin color, texture, thickness, degree of photo damage, and presence/absence of hair (Table 8-21) ○ Advantages: better overall appearance than STSG, retains adnexal structures (and function), better contour and texture match; greater thickness ➔ ↓wound contracture ○ Disadvantages: ↑metabolic demand ➔ ↑rate of graft failure ○ Oversize graft by 10%-20% to account for graft shrinkage after harvesting ○ Defatting (classic teaching): leaving fat on underside of graft has long been thought to reduce survival ➔ most books recommend complete removal of adipose tissue on graft However, recent studies suggest defatting is not necessary and skin-fat composite grafts survive extremely well, especially on noseGraft physiology - list the graft blood supply stages• Physiology ■ Imbibition (24-48 hours): first stage, ischemic period ○ Fibrin attaches graft to bed ○ Graft is sustained by passive diffusion of nutrients from plasma exudate of wound bed ○ Graft becomes edematous ■ Inosculation (48-72 hours, lasts 7-10 days): second stage ○ Revascularization resulting in linkage of dermal vessels between graft and recipient wound bed ■ Neovascularization (day 7): last stage critical to graft survival, occurs in conjunction w/ inosculation ○ Capillary and lymphatic ingrowth from recipient to graft ➔ revascularization complete by day 7 ○ Edema begins to resolve ■ Reinnervation/Maturation (starting at 2 months): slow process that is not completed for many months to yearsSplit thickness skin graft - comprised of what? - advantages? - disadvantages - how are they classified? which is used in what areas?Split-thickness skin graft (STSG): ○ Comprised of full thickness epidermis and variable amount of dermis ○ Advantages: covers larger defects (>5 cm), ↑graft survival (as a result of ↓demand for nutritional support), and easier detection of tumor recurrence ○ Disadvantages: ↓cosmesis, ↑contraction (➔ not recommended near free margins), lacks adnexal structures, ↓anchoring to BMZ (➔ bullae within graft site), requires specialized instruments, and painful donor site ○ Classified by overall thickness: Thin (0.005-0.012 in) Medium (0.012-0.018 in) ➔ head and neck Thick (0.018-0.030 in) ➔ trunk and extremities ○ Instruments Weck blade: specialized free-hand knife with accompanying templates for various graft thicknesses Zimmer: electric dermatome used to harvest large STSGs of various thickness and width Mesher: flat bed with roller that compresses STSG on plastic template with grid-like etched pattern that puts fine fenestrations into the graft Meshing enlarges size of STSGs by 25%-35% and increases flexibility Allows serosanguineous drainage from recipient bed, which may otherwise interfere with graft adherence and survivability Disadvantage: fenestrations often permanent ➔ ↓cosmesisComposite grafts - what are they?■ Composite grafts: - modified FTSG that contains more than one tissue component, most often cartilage; dependent on bridging phenomenon (rapid revascularization) for survival ○ Skin + cartilage graft: cartilage is used to restore structural integrity, especially of the nasal ala, to prevent anatomic distortion and alar collapse during inspiration; very high metabolic demand, very high risk of necrosis For highly sebaceous distal part of the nose, free cartilage graft harvested from ear favored +/− delayed graft/local flap for better tissue match Recommend oversizing graft by 10%-15% to tuck the edge into subdermal space (the "pocket") of recipient site ○ Skin + fat More tenuous survival than FTSGs because of reduced access to vascular supply; graft size should be 1-2 cm in maximal diameter to minimize risk of necrosis; consider delayed graft to increase likelihood of survival Caution in elderly patients, smokers, and those with conditions of vascular compromise (diabetes, vasoocclusive disease, and h/o ionizing radiation at graft recipient site)Xenografts - what are they - advantages - disadvantages■ Xenografts: ○ temporary grafts, usually harvested as STSG from swine; function as biologic dressings and promote granulation; remain in place for 7-14 days; most commonly utilized in secondary intention healing or delayed repairs ○ Advantages: ↓wound care demands for patient; protect/preserve bone, cartilage, tendons, and nerves; ↓postoperative pain at granulating site ○ Disadvantages: must be replaced 1 to 2 weeks after application, contraindicated in patients with pork allergy, and is malodorous after 10-14 days- The vast majority of wounds created during cutaneous surgery are classified as? - do wounds that are healing with secondary intent have increased risk of infection compared to sutured wounds? - when do wound infections occur? - #1 bacterial culprit, what is common on the ear - How do you treat infections with and without abscess? - what antibiotics should be used?• Infection ■ Vast majority of wounds created during cutaneous surgery are classified as "clean" ➔ low infection rates (1%-2%) ■ Second intention wounds paradoxically have lower risk than sutured wounds (Table 8-22) ■ Presents 4-8 days postoperatively ■ Symptoms: rubor (erythema, often extending asymmetrically from suture line), dolor (pain), calor (warmth), and tumor (swelling); may also have purulent discharge, lymphangitic streaks, fevers, and chills ■ Staphylococcus aureus is #1 culprit overall ○ Pseudomonas is common on ear ○ Always obtain wound culture ■ Treatment: ○ Abscesses: traditional dogma is to incise, drain, and pack the infected wound until it heals by second intention; recent studies suggest that wound may be sutured immediately following drainage ○ Surgical site infection without abscess: start antibiotics (first generation cephalosporin, β-lactamase-resistant penicillin, or penicillin/ β-lactamase inhibitor combination); consider clindamycin, doxycycline or TMP-SMX if high index of suspicion for MRSA ■ Differential diagnosis: contact dermatitis (itchy) and inflammatory suture reaction (usually presents later)Describe the wound contamination classificationsClass Attributes Percent That Develop Infections Clean (Class 1) Technique immaculate Noninflammatory 1-4 Clean-contaminated (Class 2) Small breaks in technique Gastrointestinal, respiratory or genitourinary tracts entered without gross contamination 5-15 Contaminated (Class 3) Major breaks in technique Gross contamination from gastrointestinal, genitourinary, or respiratory tracts 6-25 Dirty and/or infected (Class 4) Wound with acute bacterial infections ± pus >25- Post operative bleeding can lead to what complications? - When is the highest risk of post operative bleeding? - Aspirin affects platelets for how long? when should it be held? - should you stop clopidogrel? - What do you do if patient is on warfarin? - What are some supplements that may increase bleeding?• Bleeding ■ Bleeding may lead to hematoma, ↑risk of infection, ↑wound tension, and dehiscence ■ Highest risk = first 48 hours postoperatively (majority within first 24 hours, after epinephrine wears off) ■ Patient risk factors: ○ Aspirin: affects platelets for 6-10 days; withhold for 10 days before and 5-7 days after surgery as long as it does not impose a risk for stroke or myocardial infarction ○ Thienopyridines (e.g., clopidogrel and ticlopidine): do not stop these medications if patient is taking for cardiac or neurologic indications ○ Warfarin: check INR to assure it is <3 before proceeding with surgery ○ Herbs and supplements that enhance anticoagulation effects of warfarin and/or inhibit platelet adhesion: feverfew, fish oil, garlic, ginger, ginkgo, ginseng, bilberry, chondroitin, vitamin E, licorice, devil's claw, danshen, dong quai, and alcohol ■ Prevention: consider minimizing undermining; consider linear closure rather than flap; drain placement; apply pressure dressing immediately after procedure and leave on for ≥24 hours- How should small hematomas be treated? - How should large expanding hematoms be treated? - list the hematoma stages? - name the oral medication that can be used to treat hematomas• Hematoma ■ Gelatin-like clots formed by blood collecting in "dead space" of wound; presents with pain, swelling, and red-purple discoloration ■ Hematomas may lead to dehiscence, necrosis, and infection ■ Small hematoma ➔ pressure sensation ○ Small and stable hematomas resolve on their own; no intervention needed but may use warm compresses to hasten resolution ■ Large expanding hematoma ➔ acute throbbing pain ○ Requires wound exploration, irrigation, evacuation of hematoma, and/or drain placement ○ Expanding hematomas in periorbital region (➔ blindness), and neck (➔ airway compromise) are considered medical emergencies ■ Early hematomas (first 48 hours postop) are fluctuant ➔ easy to aspirate with a 16 or 18 gauge needle ■ Organized hematomas (≥1 week postop) are thick, fibrous, and adherent to surrounding tissue ➔ cannot be aspirated ○ ~Two weeks postop, organized hematomas undergo liquefaction ➔ can be aspirated, or left alone to self-resorb (over many months) ○ Bromelain (Ananase, Delta Labs; Traumanase, Aventis): oral concentrate of proteolytic enzymes derived from the pineapple plant ➔ expedites hematoma resolution- What is the earliest sign of ischemia? - what are some causes of ischemia - risk factors - Treatment of surgical site necrosis? should debridement be performed?• Ischemia/necrosis ■ Earliest sign of ischemia is pallor ○ Arterial insufficiency: ↓skin temperature, lack of bleeding following pinprick test; flaps can remain viable for up to 12-14 hours ○ Venous congestion: cyanotic-purple sskin color, ↑dark purple bleeding following pinprick test; flaps undergo rapid necrosis (<3-4 hours) ■ Caused by: hematoma, infection, and ↑wound tension ■ Risk factors: ○ Patient-related: smoking, nicotine-containing products ○ Procedure-related: extensive superficial undermining, postoperative edema, sutures tied too tightly, and insufficient or excessive electrocoagulation ■ Prevention: appropriate intraoperative hemostasis, minimize wound closure tension ■ Treatment: suture replacement (↓tension), elevation (↓edema), heat application (↑circulation), and hyperbaric oxygen (↑oxygenation) ○ Do NOT debride necrotic tissue (unless shows signs of infection), since it serves as a biologic dressing- When is the highest risk of wound dehiscence? - Should dehisced wounds be re-sutured?• Dehiscence ■ Separation of wound edges as a result of excessive tension, infection, or necrosis ■ Highest risk = time of suture removal ○ Consider removing sutures in stages if prolonged support is needed ■ Treatment: ○ Classic teaching: resuture if within 24 hours; if >24 hours ➔ let it granulate on its own ○ Recent literature supports resuturing if no infection, hematoma, necrosis, or after underlying complication has been treatedHow do you treat the following things? - chondritis - contour irregularities - ectropion (what test can be done to assess risk pre-op?) - how do you avoid eye brow raising? - pincushoning (Increased risk with what types of flaps? treatment?) - spitting sutures (increased risk with what sutures? when do they occur?) - suture granulomas (increased risk with what sutures?) -• Abnormal healing ■ Chondritis: painful; may occur after any ear procedure involving cartilage; may be a/w PSEUDOMONAS infection; treat w/ NSAIDs + quinolones (if infected) ■ Contour irregularities: treated w/ dermabrasion (6 weeks postoperatively) ablative laser, or excision ■ Ectropion: ○ Cause: downward tension on lower lid ○ Risk factors: poor recoil on "snap test" ○ Prevention: tacking sutures to periosteum and FROST suspension sutures ■ Eyebrow elevation: avoid closures that elevate brow >3 mm (unlikely to self-resolve) ■ Free margin distortion: avoided w/ proper surgical design ■ Keloids: often patient- and site-specific (anterior neck, chest, and scars crossing jawline); treat w/ intralesional corticosteroids ■ Pincushioning/trapdoor deformity: ○ Risk factors: frequently as a result of concentric contractile forces ➔ flaps w/ curved incision lines have highest risk (e.g., bilobed flaps and nasolabial transposition flaps) ○ Prevention: wide undermining appropriate sizing of flap, ensure adequate flap adherence to wound base ○ Treatment: intralesional corticosteroids (into SQ) +/− scar revision ■ Spitting sutures: ↑risk w/ Vicryl or sutures placed superficially in dermis, occurs 1-3 months postop; remove if possible ■ Suture granulomas: ↑risk w/ Vicryl, occurs 1-3 months postoperatively; self-resolves without sequelae, but may treat w/ intralesional steroids ■ Telangiectasias (neovascularization): treated w/ pulsed dye laser ■ Thickened scars: treated w/ massage or intralesional corticosteroids ■ "Track marks": do not tie sutures too tightly or leave in place for too long; consider running subcuticular epidermal closure ■ Webbed or contracted scars: consider Z-plasty revisionScar improvement - scars mature over what period of time? - when can you consider scar intervention? -Overview • Scars mature over at least 2 years, but if not exhibiting favorable characteristics, may consider intervention after 60-90 days • Manage expectations ■ Goal is to improve, not erase • Result depends on ■ Size ■ Location ■ Patient's predisposition for appropriate wound healing • Favorable scars ■ Positioned along aesthetic subunit borders ■ Parallel with relaxed skin tension linesWhat is the mechanism of action of steroids for scar improvement What is the mechanism of action for imiquimod for scar improvementNonsurgical modalities • Watchful waiting • Massage ■ Efficacy greatest in postsurgical scars ■ Often best for subtle imperfections ○ Mildly depressed scars ○ Mild webbing ○ Mild pin cushioning • Pressure therapy ■ Allows natural scar maturation process to progress ○ Thins the dermis ○ Decreases edema ○ Decreases blood flow and oxygen ■ Loses efficacy after 6 months of treatment • Topical scar therapies ■ Silicone sheeting and gel ○ Mechanism unclear ○ Side effects (SEs) Skin maceration Rash ■ Vitamin E ○ Efficacy not proven in clinical trials ○ Noted to cause allergic contact dermatitis ■ Steroids ○ Mechanism of action: Binding of nuclear steroid receptor Decrease activity of fibroblasts and decreases collagen production ○ Clinical activity Softens scars and ↓hypertrophy/pin cushioning ○ Group I most efficacious, but ↑risk of SEs ■ Imiquimod ○ Mechanism of action Stimulates IFN-α ➔ ↓TGF-β (note: ↑TGF-β levels are a/w keloid formation) IFN-α ➔ ↑collagen breakdown ○ Clinical activity Prevention of keloid recurrence after excision Results of studies have been mixed ○ Cream is applied nightly for 8 weeksWhat is the mechanism of action for for 5FU in treating scars?• Intralesional therapies ■ Steroids ○ Primarily used for hypertrophic and keloidal scars ○ Mechanism of action and clinical activity: same as for topical steroids ○ Consider intraoperative injection if patient has a history of keloids ■ 5-FU ○ Primarily used for hypertrophic and keloidal scars ○ Mechanism of action Blocks transforming growth factor (TGF)-β2 gene in fibroblasts ➔ ↓collagen production ○ Clinical activity Softens scars and decreases hypertrophy ○ Can be used in combination w/ steroidsLasers - PDL : Wavelength, laser of choice for what things, what is an important consideration when using this laser - NDYAG: wavelength, clinical use - CO2 wavelength, erbium-YAG wavelength - What is the difference between ablative and non-ablative lasers?• Lasers ■ Pulsed dye laser 585-595 nm ○ Laser of choice for red, hyperemic, pigmented, or hypertrophic scars and keloids ○ Patient phototype important as melanin competes for laser absorption. Must use lower energy densities in darker skin tones. ○ Mechanism of action Keloids: promotes scar remodeling as a result of nonspecific heating of dermal collagen Redness: destruction of dermal vessels ■ Nd:YAG - 1064 nm ○ Noted to improve pigmentation, vascularity, pliability and height of keloids, and hypertrophic scars ■ Resurfacing lasers ○ Mechanism of action Dermal heating leads to scar remodeling ○ Types - Ablative (CO2 - 10600 nm; Erb:YAG - 2940 nm) Destroys stratum corneum and deeper structures Uses: recontouring atrophic scars ➔ reported equivalent cosmesis to dermabrasion w/ faster clinical recovery - Nonablative Preserves stratum corneum with destruction of deeper structuresNail Surgery - which is less traumatic: a distal or a proximal nail fold avulsion? - Nail bed biopsy: what type of incision is made? how deep does it go? is suturing required? - Nail matrix biopsy: - most nail melanomas arise from where? - what is a matricectomy? why would this be done?• Nail avulsion: typically undertaken for treatment of onychomycosis, onychomadesis, nail biopsy, nail matrix ablation, or nail unit excision ■ Distal nail avulsion (most commonly used technique): entire nail is separated from distal nail bed to proximal nail fold ■ Proximal nail avulsion: less traumatic than distal nail avulsion; undertaken when there is prominent subungual hyperkeratosis ■ Partial nail avulsion: used when exact location of lesion in question is already known • Nail biopsies ■ Nail bed: ○ Longitudinal excision; excision extends down to periosteum; +/− suturing of defect (not required if defect width ≤3 mm); minimal risk of nail dystrophy ■ Nail matrix: ○ Horizontal excision; make diagonal 5 mm incision from proximal nail fold (extending proximally on finger) to allow visualization of matrix ➔ biopsy carried down to periosteum ○ Matrix biopsies have ↑risk of nail dystrophy/ thinning; highest risk w/ proximal matrix biopsies and if >3 mm width ○ Most nail melanomas arise from matrix ➔ matrix biopsy required ➔ ↑risk of nail dystrophy ■ Lateral longitudinal nail biopsy: ○ Longitudinal excision used for lesions on lateral nail fold, proximal nail fold, or lateral portions of matrix/bed ○ Main risks = spicule or cyst formation • Matricectomy ■ Removes nail matrix ➔ inability to form a new nail ■ Indications: ingrown nail/onychocryptosis (#1) or onychomadesis ■ Typically only the part of the matrix causing problems needs to be removed ■ Excision of nail unit ○ En-bloc excision is typically undertaken for removal of malignant tissue, such as a subungual melanoma; aggressive procedure that may result in permanent stiffness at the joint, but may be preferable to amputation ○ Excision must be taken back to DIP tendon insertion to have reasonable chance of removing entire matrixphenol matricectomy - used mostly for what, how is the phenol applied, is ECG monitoring required? What is the procedure used to fix a subungal hematoma? when is it indicated?■ Phenol matricectomy ○ Mostly used for ingrown toenails ○ Phenol is applied three times with a cotton-tipped applicator for 2-3 minutes after nail avulsion ○ ECG monitoring is not necessary; some will neutralize the phenol with alcohol after application ■ Excision and electrodesiccation of the nail matrix have been advocated by some authors as alternatives to phenol; limited data exist on its benefits and harms relative to other forms of nail matricectomy ■ Subungual hematoma: ○ Trephination indicated if hematoma >50% of nail ○ May occur in combination w/ fractured distal phalanx ➔ X-rays recommendedStages of wound healing - name the three stages - First thing to respond (what do they release), first ECM component deposited? - what causes vasodilation? - First cell to respond, when do they get there? what do they do? what attracts them? - Next cells to arrive? how do they set the stage for the proliferative phase?• Three phases: inflammatory, proliferative, and remodeling ■ Inflammatory phase (starts within first 6-8 hours, and can last 3-4 days): ○ Clot formation and coagulation are initial steps Platelets come to site of wound first ➔ release various factors (ADP, clotting factors, PDGF, EGF, fibrinogen, fibronectin, TGFα, and TGFβ), some of which are chemotactic for platelets, fibroblasts, and immune cells; interact with fibrin - Fibrin (first ECM component deposited) and fibronectin (helps provide a matrix for fibroblasts to rebuild) are essential to the process of clotting and coagulation Important to remember that the clot must be cleared (by plasminogen/plasmin and metalloproteinases) for appropriate scar healing ○ Vasodilation caused by histamine, prostaglandins, complement, and kinins ○ Influx of neutrophils in first 48 hours (fibrinogen/fibrin products, C5a, and other cytokines chemoattract neutrophils) Involved in clearance of bacteria and debridement ○ Macrophages arrive next ➔ they are the cell type that is ABSOLUTELY REQUIRED for wound healing!!! Phagocytose/debride tissue/organisms and set the stage for the proliferative stage (via secretion of growth factors ➔ ↑fibroblasts and ECM development)Proliferative phase of wound healing - Starts when? initiated by what? these are released by what? - what mediates reepithelialization? when does it begin - what produced by what helps with keratinocyte migration? - what is granulation tissue? what is needed for granulation tissue? and what is granulation tissue replaced by? - what mediates wound contraction? what do these cells contain? when is maximum contraction? - neovascularization is mediated by what? when does this start?■ Proliferative phase (starts around day 5-7 and may last up to 1 month): ○ Initiated by growth factors (PDGF, TGF-α/β, FGF, and others) released by macrophages ○ Reepithelialization beginning within 24 hours, and is mediated by EGF, KGF, IGF-1, and other growth factors released by fibroblasts, platelets, and keratinocytes. Keratinocytes from sites adjacent to the wound leapfrog over each other (lateral mobilization 2° to breakdown of desmosomes) ➔ reepithelialization Collagenase produced by monocytes also helps with keratinocyte migration ○ Formation of granulation tissue (macrophages, fibroblasts, and vessels) at 3 to 5 days, and deposition of extracellular matrix scaffolding for repair - Fibronectin needed for granulation tissue formation ➔ replaced by collagen III and ultimately collagen I ○ Fibroplasia at 3 to 14 days - deposition of collagen and other ECM components by fibroblasts (migrate about 2 days after wound creation; rely on fibronectin framework for migration/travel) Wound contraction mediated by myofibroblasts (maximal at 1-2 weeks; these cells contain actin microfilaments) ○ Neovascularization/angiogenesis - mediated by VEGF, TGF-β, angiogenin, and other molecules Starts in first week of wound healingRemodeling phase of wound healing - starts when and can last how long? - describe the remodeling phase: formation of what? regression of what? - what are the first cells to undergo apoptosis? what are the last? Scar strength at 1 week, 3 weeks, 3 months, 1 year■ Remodeling (starts at 3-4 weeks and can take 1 year): ○ Scar matrix formation (via fibroblast production of collagen/fibronectin/hyaluronic acid), and regression of granulation tissue (endothelial cells are first to undergo apoptosis and macrophages are last); collagen remodeling • Scar strength (High-Yield!) ■ 1 week: up to 5% ■ 3 weeks: 20% ■ 3 months: 50% ■ 1 year: 80%Laser stands for what? - what are the three Cs that characterize lasers? - what are the different media for lasers? what do they determine? - what are the media for the following lasers? CO2, excimer, PDL, ER-YAG, alexandrite, diode• LASER = Light Amplification by Stimulated Emission of Radiation (Table 9-1) • Lasers are characterized by the "3 C's" ■ Coherence: light waves travel together in-phase in time and space ■ Collimation: light waves travel together in a parallel fashion ■ (mono)Chromatic: light waves are all the same wavelength • Three different media exist (determine laser wavelength): ■ Gas: CO2, xenon chloride (excimer laser), krypton, argon, copper vapor, helium-neon ■ Liquid: rhodamine dye (PDL) ■ Solid: two classes exist ○ Crystal: alexandrite, Er-YAG, Nd-YAG, potassium titanyl phosphate (KTP), and Ruby ○ Semiconductor: diodeWhat is selective photothermolysis? - it depends on what three factors? - pulse duration should be shorter than what? - Discuss the following types of laser waveforms Continuous, Pulsed, quality switched, and quasicontinuous• Selective photothermolysis: using a laser to achieve selective destruction of the target structure(s); depends on three factors: ■ Wavelength must target the desired chromophore and reach an appropriate anatomic depth to destroy the desired target tissue ■ Pulse duration should be ≤ TRT (thermal relaxation time) ➔ minimizes diffusion of heat and resultant "collateral damage" to surrounding tissues ■ Fluence must be high enough to damage target tissue, but not so high as to nonspecifically damage bystander tissue • Four different types of laser wave forms: ■ Continuous: emit light continuously; low power (examples: CO2 laser, and argon) ■ Pulsed: light is emitted periodically, with short pulse durations (millisecond [ms] range), and high power (examples: PDL, ruby, alexandrite, diode, Erbium:glass, and Erbium:YAG) ■ Quality switched (Q-switched): variant of pulsed lasers with extremely short pulse durations (nanosecond range); extremely high power (example: all QS lasers) ○ Lasers of choice for pigmented lesions, tattoos, and drug deposits, because target molecules are very small ➔ very short TRT (nanoseconds) ■ Quasicontinuous: emits multiple rapid bursts of low-energy light ➔ simulates continuous wave lasers (examples: KTP and copper vapor)- When laser hits the skin, what % is reflected? - when light enters the skin, what are the three things that can happen to the light - What controls the amount of scattering?• Treated skin will have at least one of the following four interactions with emitted laser light particles: ■ Reflection: 4-7% of light is reflected ("bounced away") by skin surface, as a result of the difference in refractive index between air and stratum corneum; the remaining 93-96% of light enters skin and will subsequently interact in one of three following ways: ○ Scattering: light bounces off fibers within dermis/ SQ ➔ limits depth of penetration ↑spot size ➔ ↓scatter ➔ ↑depth of penetration ○ Transmission: light passes straight through the tissue without interacting with anything ➔ lack of any effect ○ Absorption (desired effect): light is absorbed by its intended target ➔ tissue effects- Epidermal damage is minimized via what? - name the three methods commonly used - IPL: What is the light source, wavelength, how does it compare in power and selectivity to LASERS? - Radiofrequency: How does it work? how does it compare in power and selectivity to other modalities? it is primarily used for what?• Epidermal damage is minimized via skin cooling (three commonly used methods): ■ Precooling: most aggressive and effective method (example: cryogen (tetrafluoroethane) spray) ○ Main side effect (SE) = hyper/hypo-pigmentation ■ Parallel cooling: only effective for pulses >5 ms in duration (example: solid cold sapphire window pressed against skin) ■ Postcooling: used primarily to ↓ pain, erythema, and edema (example: ice packs and cold air) • A variety of lasers exist, each with specific wavelengths, target chromophores, and depths of penetration (Fig. 9-1 and Fig. 9-2) • Nonlaser energy sources ■ Intense pulsed light (IPL): ○ Xenon flashlamp (light source) emits noncollimated, noncoherent, and polychromatic light (broad wavelength range: 500-1200 nm) ○ A variety of filters are utilized to narrow down the range of wavelengths to target the same chromophores that lasers do ○ Less selective and less powerful than lasers ■ Radiofrequency (RF): ○ Electrodes deliver alternating electric current ➔ locally heats tissue ○ Much less selective and less powerful than lasers and IPL, but does have some specificity for fat (hence, RF is used primarily for cellulite, and to a lesser extent, skin tightening)- Spot size: Definition, how does spot size relate to depth of penetration and scatter? - what are the four categories of wavelength and their ranges - Do longer or shorter wavelength penetrate more deeply? (this rule holds true till when?) what are the longest penetrating wavelengths? least penetrating wavelengths - What are the major chromophores of the skin?Spot size - Diameter of the laser beam hitting the skin surface (mm) - mm Larger spot size ➔ ↓scatter ➔ ↑depth of penetration Wavelength Length of a specific laser's light wave -Four categories: UV (10-400 nm) Visible (400-700 nm) Infrared (700 nm-1 mm) Radiofrequency/microwaves (>1 mm) nm (most commonly) - Longer wavelengths penetrate deeper (rule holds true until 1300 nm, at which point penetration decreases as a result of water absorption) - Most deeply penetrating wavelengths = 650-1200 nm - Least penetrating wavelengths = far UV and far IR Chromophore Absorptive target tissue of laser — - Major chromophores in skin (boards favorite): melanin, hemoglobin (oxyhemoglobin and deoxyhemoglobin), and water - A laser/light source may target multiple chromophores to differing degrees- What is the thermal relaxation time? measured in what? proportional to what? how should pulse duration compare to TRT? What if it is longer than TRT? - What is the photomechanical effect? what is it responsible for?Thermal relaxation time (TRT) - The time required for heated tissue to dissipate 50% of its heat - Seconds (or fractions of seconds); - proportional to the diameter of target squared - TRT (seconds) is proportional to the square of the target's diameter (in mm) - Ideally, pulse duration should be ≤TRT - If pulse duration > TRT ➔ ↑undesired damage to surrounding tissues (Table 9-2) Photomechanical effect - Sudden heating produces thermal expansion with acoustic and/or shock waves ➔ waves produce cavitation (steam bubbles) — Cavitation is the primary mechanism of vessel rupture w/ PDL, and also is responsible for skin whitening during QS-laser treatment of tattoosWhat are the four main concerns when using laser? Blindness: what % of laser light is reflected by the stratum corneum? - any laser in the What range can lead to lens damage or cataracts? provide example laser? and what is its wavelength? - lasers that target melanin or hemoglobin can lead to what? highest risk with which lasers? - lasers that target water can lead to what eye problems? - which lasers have the greatest risk of causing fire? to reduce fire risk intraoperative O2 should be less than?• Four main concerns: blindness, fire hazards, cutaneous burns, and inhalation of biohazardous plume • Blindness ■ Up to 7% of emitted laser light is reflected by the stratum corneum ➔ reflected light can cause eye damage/blindness (may occur if even 1% of the beam is reflected into eye) ■ Blindness is rapid and painless ■ Any laser/light source in UV range ➔ lens damage, cataracts ○ Example: excimer laser (308 nm) ■ Any laser/light source that targets melanin or hemoglobin (visible light and near-infrared wavelengths) ➔ retinal damage (retina is highly pigmented); also damages uvea and iris ○ Examples: KTP (532 nm), PDL (585-600 nm), ruby (694 nm), IPL (various wavelengths), alexandrite (755 nm), diode (800 nm), and Nd:YAG (532 nm and 1064 nm) ○ Highest risk = near infrared and Q-switched lasers ■ Any laser/light source that targets water (mid and far-infrared wavelengths) ➔ corneal/scleral damage ○ Examples: Nd:YAG (1320 nm), Erbium:glass (1550 nm), Erbium:YAG (2940 nm), and CO2 (10600 nm) • Fire hazard ■ Greatest fire risk with CO2 and Erbium:YAG ablative and fractionated lasers ■ Risks: drapes, clothing, dry hair, and plastic tubes (endotracheal tubes, especially if oxygen is being administered) ■ Prevention: moisten hair near treatment field, ensure that any alcohol/acetone skin cleanser has fully dried before using laser, and reduce intraoperative O2 concentration <40%Cutaneous burns can result from use of what lasers? How can you prevent HPV inhilation when using lasers?• Cutaneous burns: may occur with any laser or nonlaser energy source (IPL and RF); as a result of operator error • Inhalation of biohazardous plume ■ HPV viral particles have been detected in laser plumes ➔ cases of laser-surgeons developing HPV-16-induced oral SCC related to inhalation ■ Prevention: ventilation and/or smoke evacuator; also recommend N95 mask Vascular lasersVascular lasers - target? absorption peaks of targets? - main side effect? other side effects - what is recommended for larger pediatric lesions - eye damage would occur where? - PDL wavelength and is the treatment of choice for what? - IPL wavelength and is the treatment of choice for what? Treats what two things? - Treatment of choice for lower leg vessles? - treatment of choice for erythrotelangiectatic rosacea?Vascular lasers • Commonly treated vascular lesions: blood vessels as a result of photoaging, redness associated with (a/w) rosacea, spider angiomas, Poikiloderma of Civatte, hemangiomas, vascular malformations, redness in striae, redness in scars, verruca vulgaris, and Kaposi sarcoma (less common) • Utilize selective photothermolysis to damage blood vessels via coagulation of vessel contents ➔ vessel collapse or destruction • Target: hemoglobins (oxyhemoglobin > deoxyhemoglobin > methemoglobin) ■ Absorption peaks = 418, 542, and 577 nm • Main SE = purpura (primarily PDL) ■ Other SEs dyschromia (↑risk in darker skinned patients), blistering (↑risk with shorter pulse widths, higher fluences, and skin of color) • Skin cooling via precooling is critical ➔ prevents epidermal damage ■ Also allows for greater patient comfort and allows physician to treat at higher, more efficacious fluences • General anesthesia is recommended for larger pediatric lesions • Site of eye damage: retina • Consider HSV prophylaxis for perioral lesions, or larger facial malformations • Desired treatment endpoints: ■ PDL - purpura (as a result of cavitation and vessel rupture) ○ Nonpurpuric regimens utilize pulse durations of 20 ms or higher ➔ do not get cavitation or vessel rupture ➔ do not get immediate purpura (but frequently get delayed purpura days later) ■ KTP, Nd:YAG - immediate disappearance of vessel • Complex vascular lesions typically require several treatments • Boards fodder: ■ PDL (585-600 nm) is the treatment of choice for most vascular lesions (PWS, telangiectasias, erythematous scars, and hemangiomas) ■ IPL is the TOC for Poikiloderma of Civatte (treats both the vessels and dyschromia) ○ If IPL is not an option on the examination, PDL would be second best choice ■ Long-pulsed Nd:YAG (1064 nm) is the laser of choice for most vascular ectasias on the lower leg (venulectasias, telangiectasias, and reticular veins), because it penetrates deeper than other vascular lasers ○ Diode (800 nm) would be the second best choice ■ IPL or long-pulsed PDL (nonpurpuric) are the treatments of choice for erythematotelangiectatic rosaceaHair Reduction lasers - common conditions that benefit from laser hair removal? - What is the target for hair reduction lasers? what is the absorption peak? - What is the site of eye damage? PIH risk is greater in whom? - Why should patients shave before treatment? patients should not do what prior to treatment - Which laser is the most affective for hair removal? which is safest in skin of color?Hair reduction lasers and light sources • Common laser hair reduction uses: removal of unwanted hair, pseudofolliculitis barbae, hidradenitis suppurativa, and pilonidal cyst disease • Laser hair reduction is based upon the principle of selective photothermolysis • Target: melanin within hair shaft, ORS, and matrix ■ Absorption peaks: broad range (~300-1000 nm) • Destruction of bulge and bulbar stem cells ➔ improved hair removal • Dark, thick terminal anagen hairs respond best ■ Thinner, lighter hair is hard to remove ■ White hair is impossible to remove (lacks target chromophore) ➔ other epilation techniques recommended • Adverse effects: ■ PIH (↑ in skin of color) ○ Recommendation: treat test spot and follow up in 1 to 2 weeks ■ Leukotrichia ■ Blistering/burning (↑risk in skin of color) may ➔ scarring • Site of eye damage: retina • Requires multiple treatment sessions, spaced 4 to 6 weeks apart; treatments often not permanent ➔ goal is "reduction, rather than removal" • Recommend shaving before treatment in order to shorten hairs ➔ ↓skin burns from hairs on skin surface • Do NOT fully remove hair shafts by chemicals, waxing, plucking, or threading for at least 6 weeks before treatment (eliminates target chromophore) • Desired treatment endpoint = transient perifollicular edema • Use wavelength-specific eyewear to protect retina • Use parallel cooling to protect the epidermis during treatment • Boards fodder: ■ Diode is most efficacious; usually safe in skin of color (but not as safe as Nd:YAG) ■ Nd:YAG (1064 nm) = safest hair removal laser in skin of color, but slightly less effectiveResurfacing lasers - Target, absorption peaks - What is the difference between ablative and non-ablative - what is the difference between fractionated and nonfractionated - advantages and disadvantages of fractionated - site of possible eye damage?• Target: water ■ Absorption peaks: 1450, 1950, and 3000 nm • May be ablative or nonablative ■ Ablative lasers function by removing skin via vaporization of target tissue ■ Nonablative lasers work via subtle thermal effects on dermis ➔ stimulates a wound healing response • May be fractionated or nonfractionated ■ Fractionated: creates thousands of microscopic thermal zones of injury (MTZ) ➔ stimulates turnover/ remodeling of epidermis and dermis ○ Advantages: ↓downtime and ↓duration of erythema compared with nonfractionated resurfacing ○ Disadvantages: less efficacious; requires more treatment sessions • Site of eye damage: cornea, sclera (burns) • Consider HSV/fungal/bacterial prophylaxis • Adverse effects: ■ Erythema (often persists for months) ■ Hyperpigmentation ■ Relative hypopigmentation (↑risk if deeper injury; may arise months after treatment) ■ Milia ■ Secondary infections ○ HSV: highest risk in first week ○ Bacteria (S. aureus, Pseudomonas) ■ ScarringAblative lasers - name the three types - describe the coagulation, bleeding and collagen retraction of each - name the wave lengths of eachErbium:yttrium scandium gallium garnet (Er:YSGG) 2790 nm Less thermal injury ➔ poor coagulation, ↑bleeding, and ↓collagen retraction Erbium:yttrium aluminum garnet (Er:YAG) 2940 nm Less thermal injury ➔ poor coagulation, ↑bleeding, and ↓collagen retraction Targets the 3000 nm absorption peak of water more effectively than CO2 laser Advantages compared with CO2 laser: ↓recovery time, ↓PIH, and erythema resolves more quickly Carbon dioxide (CO2) 10,600 nm More thermal injury ➔ good coagulation, minimal to no bleeding, and ↑collagen retraction Depth of ablation is increased by performing more passesTattoo removal lasers - what type of lasers are required? why? - what is the desired endpoint when treating? what is this a result of? - what types of tattoos are the easiest and most difficult to treat? - Brown blue and black treated with? - green treated with? - white, yellow, red, violet treated with? - which tattoo pigment is most likely to cause allergy?Tattoo removal lasers (Table 9-5) • Tattoo pigments are very small in diameter ➔ very short TRT (nanoseconds) ➔ QS-lasers are required • Immediate tattoo whitening (desired endpoint) is a result of cavitation • Amateur tattoos and black tattoos are the most responsive to treatment (usually <5 treatment sessions) • Professional tattoos and multicolored tattoos most difficult to treat (>10 treatment sessions) • Boards fodder: ■ Mnemonic: "The 3 B's (black, brown blue tattoos) RAN away when they saw the 3 lasers" ➔ all 3 colors are treated with Ruby, Alexandrite, or Nd:YAG ■ Mnemonic: "If you have a Yellow, White, Red, or Violet tattoo, You Will Return Visit for 2 or more treatments with frequency-(2)doubled Nd:YAG" ■ Only ruby and alexandrite treat green tattoos ■ Red tattoos (cinnabar [mercuric sulfide]) ➔ most likely to cause allergic reactions- Laser treatment in patient allergic to tattoo dye could lead to what? - why might white tattoos undergo immediate paradoxical darkening after laser treatment - why might pink or flesh colored or light red tattoos under go immediate paradoxical darkening after laster treatment? - how are pigmented lesions like nevus of ito/ota treated? which is laser of choice? - how do you treat minocycline induced pigmentation?■ Laser treatment in patient allergic to tattoo dye ➔ possible anaphylaxis ■ White tattoos may undergo immediate paradoxical darkening (turns black or blue) with laser because of reduction of Ti4+ ➔Ti3+ ■ Pink, flesh-toned, or light red tattoos (classically,permanent lip liner) may undergo immediate paradoxical darkening (turns brown-black) with laser because of reduction of ferric oxide (Fe3+) ➔ ferrous oxide (Fe2+) ■ Traumatic tattoos from gunpowder/fireworks ➔ may explode with laser ■ Pigmented lesions (lentigines, ephelides, or nevus of Ota) are treated with the same lasers as black tattoos ("RAN" lasers) ○ Ruby is classically the laser of choice for nevus of Ota/Ito ■ Minocycline hyperpigmentation ➔ treated with the same lasers as black tattoos ("RAN" lasers)Botulinum toxic is derived from what kind of bacterium? - how many subtypes of botulinum toxin are there? which are used clinically? - What is the mechanism of action for botulinum toxin? - Rhytides typically run in what direction relative to underlying muscle? - pregnancy category, dont give with which antibiotics? - what can be given to help with eyelid ptosis? - what can be given to help with bruising• Botulinum toxin is a neurotoxin derived from the anaerobic gram(+) bacilli Clostridium botulinum • There are eight subtypes of botulinum toxin (A-H) (Table 9-6), but only two (types A and B) are in clinical use • Mechanism: Botulinum toxin inhibits the function of nerve terminals through presynaptic blockade of SNARE complex ➔ prevents acetylcholine (Ach) release ➔ chemical denervation of muscle ➔ over time, the muscle undergoes atrophy (Fig. 9-3) • FDA-approved for the temporary improvement in the appearance of glabellar lines and the lateral canthi lines, as well as axillary hyperhidrosis ■ Effect typically lasts about 3 months, and may take up to 1 week to demonstrate full effect ■ Remember, rhytides are perpendicular to muscle fibers • Three forms of botulinum toxin type A and one form of botulinum toxin B currently marketed in the USA (Table 9-7) • Typical botulinum toxin injection points are shown in Figure 9-4 and injection doses are shown in Table 9-8 • Pregnancy category C; contraindicated with neuromuscular disorders (e.g., myasthenia gravis, Lambert-Eaton syndrome, or amyopathic lateral sclerosis) • Do not give with aminoglycoside antibiotics (e.g., gentamycin) ➔ ↑ neuromodulatory effect • One of the possible SEs of botulinum toxin injections is eyelid ptosis (do NOT inject lateral to mid-pupillary line); prescription: α-agonist (apraclonidine 0.5%, naphazoline, or phenylephrine 2.5%) ➔ stimulates Muller's muscle ➔ improves eyelid ptosis ■ Other SEs (depend on site injected): blurred/double vision, mouth droop (depressor labii inferioris), difficulty speaking (orbicularis oris), cheek drooping (zygomaticus - be careful when injecting crow's feet!), swallowing difficulties (platysma), and bruising (arnica and bromelain can help with bruising)- Treatment for filler occlusion? - Anaphylaxis to filler is most common with what type of filler? What do you do before injecting?• Complications (may occur with all fillers): ■ Ecchymoses ○ Avoid platelet inhibitors and vitamin E for 10 to 14 days before procedure ■ Nodules as a result foreign body granulomas ○ HA-fillers ➔ "blue nodules" as a result of Tyndall effect (Fig. 9-5) ○ Prescription: IL-steroids; inject hyaluronidase for HA fillers ■ Painful blanching or cutaneous necrosis from occlusion of artery ○ Highest risk in glabellar region ○ Prescription (blanching): warm compresses and topical nitroglycerin?; inject hyaluronidase for HA fillers ○ Prescription (necrosis): wound care ■ Blindness from occlusion of supratrochlear and supraorbital arteries can lead to occlusion of the central retinal artery ○ Highest risk in glabellar region ■ Anaphylaxis (rare) ○ Highest risk with bovine collagen (Zyderm, Zyplast; all currently off the market) ➔ must perform two skin tests before treatment with bovine collagen ○ Very low risk with current fillers ■ Prophylaxis against HSV may be indicatedName the non-HA filler types• Non-HA fillers of significance ■ Polymethacrylate (ArteFill®): permanent filler for deep wrinkles ○ Polymethacrylate suspended in bovine collagen - thus skin testing required 30 days before procedure ○ Deep dermal injection ■ Calcium hydroxyapatite (Radiesse®): used in deep wrinkles and HIV lipoatrophy, hand rejuvenation, etc. ○ 9-18 month duration ○ Radio-opaque - seen on imaging ■ Poly-L-lactic acid (Sculptra®): used in HIV lipoatrophy, as well as deep wrinkles ○ 18-24 month duration ○ "Rule of 5's" for massage of product - 5 minutes × 5 times/day × 5 days ○ Important to inject deep or else ➔ papules/ nodules ○ Idiopathic immunologic responses may occur immediately or up to 1 year after injection- What is G prime? increased G prime means what? -• Differences between various HA fillers (Table 9-10) is as a result of the following: ■ Concentration: refers to the concentration of HA and includes both the free and cross-linked HA ○ Free HA does not contribute to the strength of the filler, only cross-linked HA does ■ Degree of cross-linking: refers to the % of the HA that is engaged in cross-links, including incomplete and complete cross-links ○ Natural HA is degraded within days; cross-linking of HA fillers results in macromolecules that are resistant to degradation ○ ↑cross-linking ➔ ↑ durability of HA fillers ■ G': represents the elastic modulus of the filler in response to shear forces ○ ↑G' ➔ ↑resistance to movement, ↓spread after placement, ↑volume support after injection ■ Viscosity: rates the flow of the filler ○ ↑viscosity ➔ more force required to push it through a syringe • Boards fodder: know the histologic features of the various fillers (see Dermatopathology chapter) and their reactionsLiposuction• Tumescent technique allows liposuction to be performed under local anesthesia ➔ ↓ risk of major SEs (e.g., bleeding, bowel perforation) • Liposuction involves the targeted removal of fat whereas many other methods rely on targeted destruction of the fatSclerotherapy - what are the most important veins of the superficial venous system in the legs? - important veins in the deep venous system? -• Superficial telangiectatic, reticular, and varicose veins of the lower legs constitutes a common cosmetic problem for patients • Risk factors: genetic predisposition, hormones (estrogen and progesterone), obesity, and pregnancy • Lower extremities have superficial and deep venous systems ■ Most important veins of the superficial venous system = small and great saphenous veins ○ These veins are typically the most cosmetically disturbing ○ Superficial varicosities located on the medial thigh ➔ suggests greater saphenous insufficiency ■ Most important veins of the deep venous system = femoral and popliteal veins • Myriad modalities are employed to treat cosmetically undesirable leg veins: sclerotherapy (Table 9-12), ambulatory phlebectomy, endovenous radiofrequency ablation, and laser ablation (Nd:YAG (long pulsed 1064 nm), IPL, and PDL); only sclerotherapy will be discussed further ■ Postprocedural compression stockings required for all forms of treatment • Sclerotherapy is the treatment of choice for telangiectasias and reticular veins ■ Foaming may allow for treatment of larger varicose veins and perforating veinsWhat are the three categories of sclerosing solutions? - what is the mechanism for each - what is foaming? Ratio, what does it allow for? - contraindications to sclerotherapy?• There are three categories of sclerosing solutions, each with different mechanisms: ■ Hyperosmotic agents: stimulate endothelial damage via dehydration (most common = hypertonic saline +/− dextrose) ■ Chemical irritants: injure endothelial cells via corrosive action (most common = glycerin) ■ Detergents: induce vascular injury by altering the surface tension around endothelial cells (most common = sodium tetradecyl sulfate (STS), polidocanol, sodium morrhuate, and ethanolamine oleate) ○ Sodium morrhuate and ethanolamine oleate can produce severe necrosis with extravasation and harbor a risk for allergic reactions ➔ not recommended for routine sclerotherapy • Foaming of sclerosing agents, ideally in a ratio of 1:4 (liquid air), is advantageous as it can ↓number of needed treatments, ↑efficacy when treating larger veins, and can be applied over a longer segment of a given vein • Contraindications to sclerotherapy: ■ Allergy to sclerosants ■ DVT ■ Advanced arterial occlusive disease ■ Symptomatic patent foramen ovale (contraindication to foam sclerosant)- type of sclerosing agent with the most and least risk of telangiectatic matting? - pain is the worst with which? - highest risk of allergic reaction with which product? -• Complications: ■ Urticaria (very common; rx: topical steroids or antihistamines; highest risk of generalized urticaria with ethanolamine oleate) ■ PIH (as a result of extravascular hemosiderin; Treatment: Q-switched lasers) ■ Telangiectatic matting (↓risk by using appropriate volume and concentration, and using low pressure when injecting; highest risk with detergents and lowest with glycerin) ■ Pain - worse with hypertonic saline ■ Swelling - important to use graduated compression stockings postprocedure) ■ Ulceration/cutaneous necrosis - highest risk on dorsal foot and ankle ■ Systemic allergic reaction - anaphylaxis (highest with sodium morrhuate and lowest with polidocanol and glycerin) ■ Inadvertent injection of an artery (most common sites of arterial injection: posterior medial malleolus [posterior tibial artery; superficial injections] and popliteal fossa [deep injections])- Where are grafts harvested for hair transplant? - What density is needed for natural transplant look - more favorable transplant characteristics?• Male pattern baldness is typically classified along the Hamilton-Norwood system • Female pattern hair loss has been graded along the Ludwig and Olsen patterns • Medical options are available and discussed elsewhere in the book • Surgical intervention involves hair transplantation (Table 9-14) ■ Based on theory of donor dominance (transplanted hair retains characteristic of where it was taken from) ■ Grafts harvested from "safe zone" in occipital scalp (unaffected by AGA) ■ Usually greater than 25 follicular units/cm2 for transplant to look natural More favorable transplant characteristics - greater than 25 yoa - larger hair shaft caliber (>70 microns) - donor hair characteristics >80 follicular units/cm - baldness mostly of the frontal scalp - salt/pepper, red, blonde hairHair Transplant - what are the two methods to harvest the grafts? - what can happen 2-3 weeks post op, new hair growth in how many weeks?■ Two methods to harvest grafts (Table 9-15): ○ Strip (elliptical) excision - cannot exceed 30 cm Typically 100 follicular units/cm2 in donor strip Leaves linear scar in occipital scalp Grafts divided from strip ○ Follicular unit extraction Punch removal of follicular units using manual, motorized, or robotic tools Each follicular unit typically consists of 2 to 3 hair shafts Less visible scarring Preferred in individuals with short hair, risk of hypertrophic/keloid scar, and in younger patients ■ Posttransplant telogen effluvium occurs 2 to 3 weeks later (self-resolves) ■ New hair growth 10 to 20 weeks postsurgery, but overall effect apparent at 6 to 9 months ■ Selected SEs: lidocaine toxicity, ingrown hairs, hypoesthesia/numbness (usually resolves within a few weeks), cobblestoning, postoperative edema of forehead (resolves within 1 to 2 weeks generally), infection, and hypertrophic/keloidal scarring at donor siteChemical peel agentsIs an interpolated malolabial flap an axial flap? A paramedian forhead flap has to be atleast how wide? what is the key tension point and key stitch in a rhombic flapNO! it is fed by branches of the angular artery - only the Abbe (labial artery) and paramedian forhead (Supratrochlear) flap are axial interpolation flaps Paramedian forhead flap has to be atleast 1cm wide The key tension point in a rhombic flap is the take off point, this is also the ket stitchMelanosome thermal relaxation time The whitish color after treatment of a pigmented lesions results from what? Fluence = ?, deepest penetrating laser Best laser for hair removal of lighter finer hair0.25ms or 250ns The whitish color after treatment of pigmented lesion represents the cavitation reaction Fluence= power NDYAG 1064 penetrates the deepest Hair removal for lighter finer hair is done with IPL-> Ruby -> ALEX -> Diode -> NDyag - opposite for darker skin and darker hairMost common germline mutation for melanoma - non sundamaged superficial spreading - chronic sun damaged - acral/mucosal - uveal Chromosomal translocation for the DFSP Second most common mutation in spontaneous BCCCDKN2A - BRAF = non-sundamaged superficial spreading - NRAS = chronic sun damaged - C KIT = acral and mucosal - GNAQ = uveal melanoma T17:22, Q21.3:Q13 P53By what factor is XP patient skin cancer risk increased, inheritance, most common type of skin cancer? BAP1 cancer syndrome is associated with what cancers First type of collagen in a wound1000X, and the most common skin cancer associated with XP is SCC, autosomal recessive melanoma, renal cell, uveal melanoma, mesothelioma collagen 3 that will be replaced by collagen 1 week 3-4Tensile strength of a wound at 1 year cells that enter a wound list the order of ECM products put down in a scar What collagen is formed in a keloid80% Platelet plug -> Platelets -> neutrophils -> monocytes -> macrophages (most important cell) Proliferative phase - fibrin, firbronectin, type 5 collagen -> type 3 collagen -> type 1 collagen if you form a keloid it is type 2 collagenThree growth factors in wound healing Merkel cell carcinoma - most commonly seen in what patient population and what area of the body? - 5 year mortality rate - 80% positive for what? Is this a good prognostic factor? - what other stain may be positive? - what antigens can be followed throughout treatment - treatment - what drugs are approved for mets, what is a poor prognostic factor?VEGF, TGFB, angiogenin - fair skin older ppl on the head or neck - 5 year mortality 30% - 80% associated with polyoma virus, this is associated with good prognosis - CK20+ is a good prognostic sign - large tumor antigen and small tumor antigen correlate with tumor burden and can be followed throughout treatment - surgery and sentinel lymph node biopsy - P63+ is worse prognosis - nivolumab and pembro approved for metastatic diseaseWhat is the mutation for SK? What medication reduces the risk of developing skin cancer s/p transplant Mitochondrial DNA changes are found on what type of skinFGFR3 Sirolimus - MTOR inhibitor Sun exposed skinWhat is the purpose of the ras Pathway? what's the function of T4 Endonuclease VRas protein are signaling pathway on cell surface receptor. Mutations-> constant activation of RAS effector pathways which leads to cellular survival and proliferation originally isolated from Escherichia coli infected with T4 bacteriophage. It has been shown to repair ultraviolet (UV)-induced cyclobutane pyrimidine dimers in DNA, which, when unrepaired, contribute to mutations that result in actinic keratoses and non-melanoma skin cancers...tested in XP, 30%reduction in BCC< 60% in AKWhat things determine the response to a chemical peel? TCA - mechanism of action? - when is frosting appreciated? - does it need to be neutralized? Jessners Solution - what are the four components? - mechanism of action - does it need to be neutralized? does it have frosting? - what are the possible side effects of resorcinol?number of coats applied, degree of rubbing, previous use of tretinoin, frequency of peels, integrity of epidermal barrier and sebaceous gland density TCA - causes precipitation of proteins and superficial necrosis - white frosting common with TCA peels at concentrations greater than 25% - does not need to be neutralized Jessners Solution - sal acid, lactic acid, ethanol, resorcinol - breaks down intracellular bridges - does not need to be neutralized - no frosting - Resorcinol can cause ochronosis, hypothyroidism, and syncopeSal acid peel - causes what? does it need neutralized? possible side effect? what does it do under woods lamp? What do you neutralized glycolic acid peel with? Phenol - superficial, medium, or dep? - requires what? - toxicities?Sal Acid Peel: - causes a white precipitate - does not need neutralized - can cause tinnitus - flouresces under woods lamp Sodium bicarbonate Phenol -Used as a deep peeling agent - acts as a keratocoagulant - required IV sedation - Renal toxicity (requires pretreatment IV fluids) - cardiac toxicity (arrythmias)