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Disorders of the nervous system and special senses

Terms in this set (129)

3 Neural tube defects
1)Spina bifida
2)Meningocele
3)Meningomyelocele
Spina bifida oculta
The spinal cord and meninges lie within an incompletely closed vertebrae, everything is in correct location
Meningiocele
herniated component outside. Meninges protrude through opening in incompletely close vertebrae but spinal cord is within the vertebrae.
Meningomyelocele
Meninges and spinal cord protrude through the incompletely-closed vertebrae
Dementia
-A cognitive decline not associated with aging
-Can be caused by many conditions and influence the portions of the brain responsible for memory a learning
3 types of Dementia
1)Alzheimer disease- Most common
2) Vascular dementia
3)Huntington's disease
Alzheimer Disease
Involve neuropathologic and neurotransmitter changes and is characterized by cortical atrophy and loss of neurons. Presence of senile plaques and neurofibrillary tangles
Senile plaques
Bundle of nerve endings
-Flat clusters of degenerating nerve terminals with a core of beta amyloid
-The plaques can release free radicals and cause vasoconstriction
Beta amyloid
Beta-amyloid is chemically "sticky" and gradually builds up into plaques.
Neurofibrillary tangles
fibrous proteins (microtubules within the neuron) wound around each other like a double helix.
When the fibers coil it causes the neuron to shrink
Alzheimer and ACH
Plaques and tangles lead to the loss of functional neurons and the inability to produce ACh.
This leads to the onset of forgetfulness followed by deficits in abstract thinking, loss of functional status and personality changes
Acetylcholine general
Neurotransmitters shift between synapses and join the receptors. Upon this blending, nerve cells related to the receptor site are activated in one of two ways.
Either they will fire in the excitatory reaction, or they will be averted from doing so in the inhibitory reaction.
Acetylcholine as Excitatory
a excitatory neurotransmitter important for
1)Nerve transmission in the cerebral cortex and the hippocampus
2)Formation of new memories
Clinical manifestations of AD
The hallmark symptoms are loss of short-term memory and denial of such memory loss, difficulty with language, and changes in behavior
Memory loss AD
randomly forget important and unimportant details. They forget where things are placed, get lost easily, and have trouble remembering appointments and performing novel tasks.
Changes in Personality AD
Mild changes such as lack of spontaneity, social withdrawal, and loss of a previous sense of humor, occur during this stage
Vascular Dementia Causes
caused by brain injury resulting from ischemic or hemorrhagic damage. The incidence is closely associated with hypertension, but also with arrhythmias, myocardial infarction, peripheral vascular disease, diabetes mellitus, and smoking
Vascular dementia symptoms
Inability of the brain and body to communicate, leads to
1)Slowness of psychomotor function
2)Dementia
3)Memory and Judgement will start to go
Huntingtons disease
An inherited form of dementia
Damage is initially seen in the basal ganglia
Decrease in GABA and GABA receptors
Decrease in ACh
Huntingtons Symptoms
-Depression and personality changes early
-Memory Changes later
-Restlessness, fidgeting
-Lead to choreiform dyskinesias
-Progress to rigidity
Basal Ganglia
The Master Monitor of All Movements

Behind all the voluntary movements that your body performs
choreiform dyskinesias
repetitive and rapid, jerky, involuntary movement that appears to be well-coordinated
dyskinesia
category of movement disorders that are characterized by involuntary muscle movements, including movements similar to tics or chorea and diminished voluntary movements. It can be anything from a slight tremor of the hands to an uncontrollable movement of the upper body or lower extremities
Torticollis
common term for various conditions of head and neck dystonia, which display specific variations in head movements characterized by the direction of movement (horizontal, as if to say "no", or vertical, as if to say "yes")
Normal motor fucnition is directed by what?
Is due to the balance of ACh and Dopamine.
Increase Dop= Decrease GABA= Excite
Increase ACh=Increase GABA= SLow
GABA
GABA is an inhibitory neurotransmitter, which means it helps to stop and reduce nerve impulses from inter-neuron communication.
With an increase in GABA, things slow down.
With a decrease in GABA< things speed up
GABA and ACH
ACh is excitatory, so with an increase in ACh, more GABA is release, which slows things down.
MORE GABA = SLOW DOWN
GABA and Dopamine
Dopamine is inhibitory in the basel ganglia.
More Dopamine, LESS GABA is released.
LESS GABA= SPEED UP
Dopamine and Parkingson
An inhibitory neurotransmitter used to balance the effects of GABA.
In PD Decrease of Dopamine leads to an increase in GABA, which has a slowing effect to movements
Parkinson Disease
The gradual degeneration of the basal ganglia due to the interaction of genetic and envi't factors
Decrease of dopamine, leading to a variable combination of tremor, rigidity and bradykinesia.
Symptoms in PD
-Tremor
-Rigidity
-Bradykinesia
-Excessive sweating and salivation
-Cognitive dysfunction (20%)
Tremor PD
Most visible symptom
Usually unilateral and occurs at rest
Rhythmic
Relieved with rest
Rigidity PD
Cog wheel movements
Resistance to flexion and extension
More visible during passive range of motion
Bradykinesia PD
slow to initiate movement
problems stopping suddenly
Myasthenia Gravis
A disorder with the motor/neuron junctor affecting transmission.
Results in a reduction in stimulation
Peak 20-30 years and is more common in women
Myasthenia cause
Its an autoimmune process
disorder of transmission at the neuromuscular junction due to antibody-mediated attack on nicotinic ACh receptors
Leads to a "shedding: of the receptors and a widening of synapse
Weak muscle contraction (MG)
Less ACh and less of the nicotinic receptors leads to a lower reduction in the transmission of the nerve impulse for muscle movement
Symptoms in Myasthenia
-Weakness and fatigability with activity
-Eye (ptosis) is common
-Chewing and swallowing may be affected
-Proximal muscles affected first
-Speech affected later
Myasthenic crisis
is a complication of myasthenia gravis characterized by worsening of muscle weakness, resulting in respiratory failure that requires intubation and mechanical ventilation.
Occurs during times of extreme stress (like septic shock)
Polyneuropathy
involve demyelination or axonal degeneration of multiple peripheral nerves that leads to symmetric sensory, motor, or mixed sensorimotor deficits. Typically, the longest axons are involved first, with symptoms beginning in the distal part of the extremities
Guillain Barre Syndrome
A disorder in which the body's immune system mediates polyneuropathy and attacks part of the peripheral nervous system. - and is considered a medical emergency.
Guillain Barre Progression
The first symptoms varying degrees of weakness or tingling sensations in the legs that spread to the arms and upper body.

These symptoms can increase in intensity until certain muscles cannot be used at all and, when severe, the person is almost totally paralyzed.

In these cases the disorder is life threatening - potentially interfering with breathing and, at times, with blood pressure or heart rate
Amyotrophic lateral Sclerosis
Lou Gehrig's Disease
-A degeneration of the motor system with the sensory system remaining intact that is more common in men over 55
ALS Etiology
Denervation leading to atrophy of muscles
ALS Symptoms
-Progressive weakness and muscle atrophy which usually starts in one upper extremity and spreads
-Difficulty swallowing and speaking
-Can spread to respiratory muscles
Multiple Sclerosis
Immune mediated attack of a protein in the CNS
The peripheral nervous system is spared
It affects women more, specially in the NE latitudes
There is a genetic link
Process of MS
Inflammation and demyelination of the CNS r/t the immune response against part of the CNS, mostly white matter.
As inflammation subsides, sclerosis form.
Lack of myelin and damage due to the inflammation cause a disruption of nerve conduction, a slowing down of nerve impulses
Sclerosis
The lesions of MS consist of hard, sharp-edged, demyelinated patches that are visible throughout the white matter as well as sometimes the gray matter. These lesions, which represent the end result of acute myelin breakdown, are called plaques
MS Symptoms
Which may come and go;
-Acute paresthesia of the face or extremities
-Optical issues including cloudiness and diplopia
-Fatigue
Diplopia
Double vision
Epidural Hematoma
Usually due to injury involving fracture of the skull; blood accumulation usually due to a tear in an artery; rapid blood loss leads to brain compression; cycling state of consciousness; Ipsilateral pupil dilation; if not removed, can lead to increase intracerebral pressure
Ipsilateral pupil dilation
dilated pupil on the same side as an epidural hematoma with contralateral limbs being paretic
Subdural hematoma / SAH (subarachnoid hemorrhage
blood accumulation in space between dura and arachnoid membranes, or subarachnoid space; blood build up due to tears in small vein that connects cerebral cortex to dural sinuses; tend to develop more slowly than epidural;
acute SAH
rapid progression; need to resolve to reduce risk of increased ICP; symptoms include - loss of consciousness that may fluctuate
chronic SAH
slow progression; symptoms may show weeks after injury; symptoms include - drowsiness, confusion, headache
Cerebrovascular accident (CVA)
Acute vascular injury that damages brain tissue
ischemic
CVA type: poor blood flow > 80%
hemorrhagic
CVA type: bleeding into brain tissue < 20%
thrombi
cause of ischemic stroke: most common cause in large vessels; Atherosclerotic disease, usually at bifurcation (origins of carotid and vertebral arteries); reduction in blood flow
embolus
cause of ischemic stroke: Usually cardiac in origin (left ventricle); patients with atrial fibrillation, rheumatoid heart disease, bacterial endocarditis are at risk; usually sudden onset;
middle cerebral artery
area most often affected by embolus ischemic stroke
Lacunar stroke
ischemic CVA type: Small infarcts affecting deep regions of brain (basal ganglia and brain stem); when they heal, they leave small cavities (lacunae); usually do not present with aphasia, apraxia, or other disorders associated with the cortex; instead, often present with pure hemiplegia (motor or sensory)
Transient Ischemic Attack (TIA)
ischemic CVA type: "mini-strokes";
Temporary disturbance in cerebral blood flow; focal neurologic deficit that lasts < 24 hours (usually < 1 hour);
self-resolve, but may be sign of impending stroke
penumbra
tissue at risk surrounding core of necrotic tissue following a stroke;
these cells are perfused poorly;
cells demonstrate impaired metabolic fxn but are structurally intact;
may progress to necrosis if adequate blood supply does not return
watershed area
area between terminal branches of cerebral arteries (ACA and MCA); hypotension can cause ischemia;
watershed stroke
defined as ischemia that is localized to the vulnerable border zones between the tissues supplied by distant terminal branches of brain arteries; associated with hypotension;
Hemorrhagic stroke
-CVA type: Most frequently associated with sudden death;
- hemorrhage into brain tissue results in edema, compression brain tissue, spasm of adjacent blood vessels
Causes of Hemorrhagic Stroke
Aneurysm, Arteriovenous malformation (AVM), trauma, coagulopathies, erosion of blood vessels by tumor
Anterior cerebral artery (ACA) stroke
frontal lobe affected.
Symptoms of ACA stroke
Problems making decisions, cognitive and affective disorders, aphasia, slow thought, easily distracted;
middle cerebral artery (MCA)
Lateral hemispheres and deep portions of brain;
Symptoms of MCA stroke
contralateral hemiplegia, contralateral sensory impairment, aphasia
aphasia
A language disorder that affects a person's ability to communicate.
contralateral hemiplegia
Paralysis occurring on the side of the body opposite to the side of the brain in which the causal lesion occurs
posterior cerebral artery (PCA)
occipital lobe; symptoms: Visual defects, visual hallucinations, memory defects
meningitis
Inflammation of the meninges; due to infection or chemical irritation; rapid spread through CSF
enteroviruses
viral causes of meningitis
streptococcus pneumoniae (neisseria meningitidis)
bacterial causes of meningitis
symptoms of bacterial meningitis
fever and chills, headache, stiff neck, photophobia, back and abdominal pains, seizures;
bacterial meningitis
more severe form of meningitis, life-threatening
astrocytoma
most common primary brain tumor; a particular kind of glial cells, star-shaped brain cells in the cerebrum called astrocytes. This type of tumor does not usually spread outside the brain and spinal cord and it does not usually affect other organs
glial tumor
brain tumor originating in the skull from brain tissue
meningiomas
brain tumor that originates from tissue other than brain tumor e.g. overgrowth of meninges
A tumor that arises from the membranes surrounding the brain and spinal cord.
seizure disorder
A seizure represents the abnormal behavior caused by an electrical discharge from neurons in the cerebral cortex.
A seizure is a discrete clinical event with associated signs and symptoms that vary according to the site of neuronal discharge in the brain
Symptoms vary according to site of stimulus -sensory, motor, psychologic phenomena
Possible causes of Seizure disorders
Altered membrane permeability to ions
Abnormal distribution of ions across membrane
Neurotransmitter imbalance (GABA and ACh)
Some genetic connections
Seizure vs Epilepsy
A seizure is a single event of abnormal discharge that results in an abrupt, altered state of cerebral function.Epilepsy is a chronic disorder of recurrent discharges from neurons
unprovoked
seizure with no identifiable cause
provoked
seizures precipitated by disease; fever, metabolic dysfunction, trauma
absence seizure (petit mal)
Absence seizures are generalized, nonconvulsive epileptic events and are expressed mainly as disturbances in consciousness. Absence seizures typically occur only in children and cease in adulthood or evolve to generalized motor seizures.
Character of absence seizure
characterized as a blank stare, motionlessness, and unresponsiveness, motion occurs in many cases. This motion takes the form of automatisms such as lip smacking, mild clonic motion (usually in the eyelids), increased or decreased postural tone, and autonomic phenomena. There often is a brief loss of contact with the environment.
Tonic-clonic seizure (Grand mal)
-Usually a vague warning (aura)
-Experiences a sharp tonic contraction of the muscles with extension of the extremities and immediate loss of consciousness.
-Incontinence of bowel and bladder may occur; followed by clonic phase;
Clonic seizure
begin with a loss of consciousness and sudden hypotonia. This is followed by limb jerking that may or not be symmetrical
Tonic seizure
there is a sudden onset of increased tone, which is maintained in the extensor muscles. It is often associated with falling
Focal Seizures types
Without impairment of consciousness or awareness (simple partial)
With impairment of consciousness or awareness (complex partial)
Generalized Seizures types
Tonic-clonic
Absence
Myoclonic
Clonic
Tonic
Atonic
ptosis
eyelid drooping; possible causes: damage to CN III, damage portion of midbrain and pons controlling lid function;
Conjunctivitis
Inflammation of the conjunctiva causing redness, tearing and possibly purulent drainage;
ciliary bodies
produces aqueous humor;
Aqueous humor passes from posterior chamber (behind iris) to anterior chamber (above iris, in front of lens);
trabecular network
mesh system that filters aqueous humor
glaucoma
increase IOP; can be primary (due to preexisting ocular disorder) or secondary (due to inflammation); peripheral vision loss occurs;
Progression of glaucoma
Increased IOP leads to degenerative change in the retina and atrophy of optic nerve; May partially be due to decreased blood flow as well as the increased pressure
primary open-angle glaucoma
most common type of glaucoma; abnormality in trabecular network that reduces flow into the Canal of Schlemm; iridocorneal angle is not obstructed
secondary open-angle galucoma
glaucoma that may be due to RBC fragments or other substance causing obstruction; Iridocorneal angle is not obstructed;
Angle closure glaucoma
Occlusion of anterior chamber by the iris; Shallow anterior chamber puts individuals at risk; Usually precipitated by pupillary dilation, which leads to iris thickening; flow is blocked from posterior to anterior chamber; unilateral headache; vision loss can occur
cataract
Opaque lens interfering with transmission of light to retina; most common cause of age-related vision loss;
non-proliferative diabetic retinopahty:
engorgement of retinal veins; development of capillary microaneurysms; hemorrhage microinfarcts - "cotton wool spots"; macular edema leading to vision disturbance
diabetic retinopathy
high blood sugar levels cause damage to blood vessels in the retina. These blood vessels can swell and leak
prolferative diabetic retinopathy:
more serious form; formation of NEW blood vessels (neovascularization) in front of the retina; fragile - can bleed into vitreous; normal movement of vitreous can pull on vessels; pulls on retina → retinal detachment → blindness
hypertensive retinopathy
Chronic elevated blood pressure leads to vascular change:
Hypertensive retinopathy progression
Initial vasoconstriction, Eventual thickening of arterioles Necrosis of endothelium Hemorrhages Microaneurysms Microinfarcts - "Cotton wool spots" Exudates
macular degeneration
Degenerative change in macula that lead to abnormalities in central vision; Dry, age-related
macular degeneration:
Atrophy and degeneration of retina
Wet macular degeneration:
Development of a neovascular membrane that leaks into the sub-retinal space; eventually scars over, retinal tissue dies, vision is lost
otitis externa
Inflammation of external ear can be mild to severe; causes: infectious agents, irritants, allergic reactions;
otitis media
Inflammation of middle ear
Otitis media causes
Often due to reflux of bacteria from nasopharynx through; eustachian tube; bacterial or viral origin; Action of pathogen and immune/inflammatory response cause tissue damage;
conductive hearing loss
When auditory stimuli are not transmitted through the auditory apparatus (ear canal, tympanic membrane, ossicles, etc.); blockage of ear canal (cerumen, foreign body) or thickening of TM;
Sensorineural hearing loss
Problems with inner ear, auditory nerve, or auditory pathway of brain; many causes: genetic, infectious, trauma, tumors, vascular issues, exposure to intense noise, medications;
vertigo
illusion of motion (spinning)
objective vertigo
vertigo: person stationary, environment moving
subjective vertigo
vertigo: person moving, environment stationary
Benign Paroxysmal Positional Vertigo
most common type of vertigo; Brief periods of vertigo associated with change in head position
BPP Vertigo causes
Associated with free-floating otoliths in the semicircular canals; make them more sensitive to position change; Physical therapy to displace otoliths is common;
otoliths "ear stones";
calcium carbonate particles that get caught in semicircular canals of vestibule;
Ménière disease
Distention of compartment in inner ear and semicircular canals filled with endolymph; May be due to inc in endolymph or dec absorption of endolymph; Fluctuating episodes of vertigo, tinnitus, hearing loss
A patient with a long history of cigarette smoking and poorly controlled hypertension has experienced recent psychomotor deficits as a result of hemorrhagic brain damage. The patient's psychomotor deficits are likely the result of which of the following?
Vascular dementia
Which of the following diseases is associated with fewer acetylcholine receptors, resulting in a lower-amplitude endplate potential, muscle weakness, and fatigability?
Myasthenia gravis
A patient suffering a thrombotic stroke is brought into the emergency department by ambulance and the health care team is preparing to administer a synthetic tissue plasminogen activator for which of the following purposes?
Thrombolysis

Explanation:Synthetic tissue plasminogen activators work with the body's natural tissue plasminogen activators to convert plasminogen to plasmin, which breaks down clots to allow for the reestablishment of blood flow. There are two causes of strokes: hemorrhagic and thrombotic, with thrombotic strokes occurring much more frequently. Thrombolytics play a large role in increased outcomes seen with thrombotic strokes.
An adult client has been admitted to a rehabilitation center after hospital treatment for an ischemic stroke. Which aspect of the client's history would be considered to have contributed to his stroke?
The client's blood pressure has historically been in the range of 150s/90s.
Explanation:

Black ethnicity, male gender, hypertension, and diabetes are all well-documented risk factors for stroke.
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