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inservice - Congenital Hearing Loss - Pasha
Terms in this set (58)
What percent of nonsyndromic SNHL is transmitted by autosomal recessive inheritance? Autosomal dominant? X-linked?
What persent of congenital sensorineural deafness is genetic vs. non-inherited?
What percent of genetic deafness is syndromic?
What is the most common malformation of the membranous labyrinth causing deafness?
Scheibe's dysplasia (cochleosaccular dysplasia).
Autosomal dominant or recessive: Branchio-Oto-Renal syndrome
Autosomal dominant or recessive: NFII
Autosomal dominant or recessive: Stickler Syndrome
Autosomal dominant or recessive: Waardenburg Syndrome
Autosomal dominant or recessive: Treacher Collins
Autosomal dominant or recessive: Pendred
Autosomal dominant or recessive: Jervell Lange Niesen syndrome
Autosomal dominant or recessive: Usher syndrome
Inheritance of Alport syndrome
Predominantly x-linked. Can be AR or AD as well.
Describe Branchio-Oto-Renal sydnrome.
"o Autosomal dominant
o Hearing loss can be CHL or SNL but is most commonly mixed.
o Otologic abnormalities can involve the external, middle or inner ear: preauricular pits, tags, microtia, EAC narrowing, ossicular malformations, facial nerve dehiscence, absence of the oval window, reduction in size of the middle ear cleft, cochlear hypoplasia or dysplasia, enlargement of cochlear or vestibular aqueduct, hypoplasia or lateral SCC
o Branchial anomalies can be laterocervical fistulas, sinuses or cysts
o Renal anomalies range from dysplasia to agenesis"
Where is the gene in NFII located. What does it encode?
on chromosome 22q12 encoding tumor suppressor protein merlin
Diagnostic criteria for NF II
"Bilateral vestibular schwannomas
Family history of NF2 in 1st degree relative plus one of following:
• Unilateral vestibular schwannoma by age 30
• 2 of meningiomas, gliomas, schwannomas or juvenile posterior subcapsular lenticular opacity (juvenile cortical cataract)
Describe Stickler syndrome. What are the 3 variants?
In a nutshell: myopia, clefting & HL
• Associated craniofacial anomalies include midfacial flattening, mandibular hypoplasia, short upturned nose, micrognathia, long filtrum
• Hearing loss can be CHL, SHL or mixed. CHL usually 2/2 ET dysfunction related to clefts. SHL is not due to structural abnl. Thought to be due to alterations in inner ear epithelium.
• Clefting can be complete but is more commonly submucous
• Most severe ocular complication is retinal detachment, occurring in 50% affected, most commonly occurring in adolescence or early adulthood.
• 3 types all having to do with different genes involved with type II and XI collagen
Type I: nl hearing or mild HL; classic ocular finding of "membranous vitreous"
Type II: moderate HL; no ocular findings
Type III: moderate to severe HL; thickened fiber bundles in vitreous
What are the differences in the 3 subtypes of Waardenburg syndrome?
• SNHL, white forelock, pigmentary disturbance of iris, dystopic canthorium (displacement of inner canthi and lacrimal puncti)
• Can also include synophrys (unibrow), broad nasal root, hypoplasia of nasal alae, square jaw, patent metopic suture
Type II: like Type I but no associated dysopia canthorum
Type III (Klein-Waardenburg): Type I plus hypoplasia or contracture of upper arms
Describe Pendred syndrome
Pathophys: defect in tyrosine iodination. Usually prelingual and profound. Temporal bone abnormalities are common and can include dilated vestibular aqueduct (DVA) and Mondini dysplasia. Associated with goiter at 8-14 years old due to failure of iodine organification. dx: positive perchlorate test (dec perchlorate discharge). tx: synthroid to suppress goiter (no effect on hearing)
Describe the hearing loss in Jervell Lange-Nielsen syndrome.
Bilateral and severe to profound.
Describe Jervell Lange Nielsen syndrome
"bilateral severe-profound snHL, cardiac abnormliaties (10% of all cases, prolonged QT, large T waves, syncope, sudden death). Dx: EKG. Tx: beta blockers, amplification"
What are the criteria for diagnosis of Alport syndrome? Treatment?
3 of the following:
• Progressive high frequency SNHL
• Family history of hematuria
• Histologic changes in the glomerular BM
• Typical eye lesions (anterior lenticonus or macular flecks)
Order UA, BUN, Creatinine
Tx: dialysis, renal transplant
What is the gene product involved in Alport syndrome?
"Mutation in gene encoding one of the chains of type IV collagen, basement membrane problems"
What is MELAS?
"Mitochondrial disorder:Mitochondrial encephalopathy, lactic acidosis, stroke-like episodes. 30% have high frequency SNHL."
What is MERRF?
"Myoclonic epilepsy & red ragged fibers, a mitochondrial syndrome. SNHL in 50%, ataxia, dementia, optic nerve atrophy, short stature."
What is Kearns-Sayre syndrome?
"A mitochondrial disorder. SNHL in 50%, external ophthalmoplegia, atypical retinal pigmentation, heart block"
What intrauterine infectious diseases cause hearing loss?
Possibly Lyme disease.
What is the incidence of congenital toxoplasmosis?
Between 1/1000 to 1/10000 live births.
What percent of infants with have sensorineural hearing loss if infected with rubella in the 1st trimester? 2nd & 3rd trimesters?
2nd & 3rd: 10-20%"
Treatment of congenital CMV.
Gancyclovir for symptomatic infants. Prevents hearing deterioration at 6m. Have to monitor for neutropenia.
Name 7 syndromes associated with middle ear anomalies and conductive hearing loss.
"Branchial-oto-renal syndrome, Treacher Collins, and Klippel-Feil, Crouzon syndrome, Apert syndrome, CHARGE association, and Goldenhar syndrome."
"What percent of autosomal recessive, non-syndromic hearing loss is due to connexin mutations?"
Connexin 26 is a protein. What's the gene?
What is DFNB1?
"Autosomal-recessive, non-syndromic hearing loss resulting from mutations in connexin 26. Characterized by prelingual non-progressive bilateral hearing loss."
What is the gene MT-RNR1?
A mitochondrial gene whose mutation can cause nonsyndromic hearing loss. It can be associated with predisposition to aminoglycoside ototoxicity and/or late-onset sensorineural hearing loss
What are the genes involved in Stickler syndrome?
Different genes involved in type II and XI collagen.
What type of cleft is usually seen in Stickler syndrome?
What is the severe eye complication in Stickler syndrome?
"Retinal detachement, occurring in 50%."
What type of hearing loss occurs in Stickler syndrome?
"CHL, SNHL, or mixed. CHL usually due to ET dysfunction related to cleft. SNHL is due to inner ear epithlial alterations."
What syndromes is Scheibe dysplasia associated with?
Complete failure of dev of inner ear
CT: hypoplastic petrous pyramid, absent cochlear/labyrinth
Rx: vibrotactile devices
progressive/fluctuating uni or bilat HL (or no HL)
Inc risk of perilymphatic gushers/meningitis from dilated cochlear aqueduct
CT: single turn cochlea (1.5 turns), wide/absent semicircular canals, no interscala septum, wide vestib aqueduct)
Rx: amplify, CI
partial/complete apasia of pars inferior (cochlea/saccule)
normal pars superior (semicirc canals, utricle)
assoc with Usher/Waardenburg syndrome
cannot dx with CT (membranous defect, need histo)
abnl cochlear duct/basal turn
mild high freq hl
difficult to diagnose by CT (membranous defect - need histo)
what are the two AD inner ear dysplasias?
"what are the two AR, membranous dysplasias?"
"scheibe's dysplasia, alexander's dysplasia"
what is the most common cause of congenital deafness
what is usher syndrome and how is it diagnosed?
most common cause of congenital deafness
congenital snHL (degen of organ of corti and stria), vestib probs
progressive retinitis pigmentosa (delayed tunnel vision/blindness), cataracts
What are the 3 types of usher syndrome?
I: profound snHL,no vestib response, blind by early adulthood (most common type)
II: mod-profound snHL,nl vestib function, blind by mid-adulthood
III: progressive snhL, progressive vestib dysfxn, varied progression in blindness
describe goldenhar syndrome
AR (hemifacial microsomia, oculo-auriculo-vertebral spectrum)
Oto sx: preauricular appendages, pinna abnormalities, eac atresia, ossic malformation,abnl stapedius/cn7/SCC/oval window, snHL
other sx: ocular/vertebral abnlties, mild MR, facial asymmetry
Describe Treacher Collins
Otologic sx: (pre)auricular deformities, EAC atresia, ossic probs, bony replacement of TM, widened aqueduct, displaced facial nerve
Other sx: maxilla/mandibular hypoplasia, downward slanting palpebral fissures, coloboma of lower eyelid, palate defects
Rx: BAHA, poss correction of atresia
describe apert syndrome
Oto sx: stapes fixation, patent cochlear aqueduct
Other sx: lobster claw hands (syndactyly), midface probs (hypertelorism, saddle nose, proptosis, high arched palate), coronal suture closure, trapezoid mouth
describe crouzon's disease
Oto sx: atresia/stenosis of EAC, ossic deformities
Other sx: cranial synostosis, exophthalmos, parrot nose, short upper lip, small maxilla, mandible prognathism, hypertelorism
congenital rubella HL pathophys, otologic sc, other sx
pathophys: atrophy of organ of corti, loss of hair cells, thrombosis within stria vascularis.
Otologix sx: severe to profound snHL, poss delayed endolymphatic hydrops
other sx: cardiac malformations, cataracts, MR, microcephaly, anemia/thrombocytopenia, lower limb deformities
"congenital syphilis HL pathophys, otologix sx, other sx, dx, tx"
pathophys: treponema pallidum that crosses placenta, often fatal
otologic sx: deafness within first 2 years of life, possibly delayed till 2nd/3rd decade of life, hennebert's sign, endolymphatic hydrops
other sx: hutchinson's triad (abnormal central incisors, interstitial keratitis of eye, deafness)
dx: VDRL, FTA-ABS, audiogram
"congenital CMV, pathophys, otologic sx, other sx, dx, tx"
pathophys: maternal CMV
Otologic: 10% hearing loss - mild to profound snHL, possibly progressive
other sx: hemolytic anemia, microcephaly, MR, hepatosplenomegaly, jaundice, cerebral calcifications
dx: intranuclear inclusions (owl eyes) in renal tubular cells in urinary sediment, anti-CMV IgM
complete membranous labyrinthine dysplasia (name and association)
Bing-Siebenmann. Assoc with Jervell Lang Nielsen
Coloboma', heart defect (endocardial cushion) , choanal atresia, retardation, genitourinary hypoplasia, ear problems.
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