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247 Cards in this Set

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What are two examinations of visual acuity (central or macular vision)?
Snellen chart (compare vision with normal population; 20/40 person can read at 20 ft what normally one can read at 40); pinhole test (if vision improves by looking through a pinhole then the loss of acuity is likely ocular)
What are two examinations of visual acuity (peripheral vision)?
confrontation testing (face to face comparison); perimetry testing
What causes enlargement of the normal blind spot?
papilledema (swelling of the optic disc caused by increased intracranial pressure)
What is a scotoma?
an abnormal pathological blind spot in the visual field of one eye where vision is lost or decreased; due to ocular, retinal or optic nerve disorder
What are constricted or contracted visual fields?
less peripheral vision, due to glaucoma or retinal degeneration, should enlarge as the distance increases like a cone, if it does not (tunnel vision) it is likely psychogenic
What is hemianopsia?
visual loss in 1/2 of the visual field of each eye; homonymous for the same side of the visual field in each eye (lesion in optic tract, superior/inferior optic radiations or the occipital lobe), heteronymous for the opposite side of field in each eye (lesion of optic chiasm)
What do optic nerve lesions produce?
scotomas or monocular blindness
What do optic chiasm lesions produce?
heteronymous visual field defects
What do optic tract or optic radiation lesions produce?
homonymous visual field defects
What is papilledema?
increased intracranial pressure causing changes in both optic discs, causes disc margins to swell and become indistinct, vessels mound over margins; flame hemorrhages may be seen around the disc, vision may initally be normal and then be impaired if untreated
What is optic atrophy?
destruction of ganglion cell axons (demyelination, ischema), which is associated with loss of visual acuity; can be seen as pale yellow to white optic disc with sharply distinct disc margins; is not caused by lesions posterior to lateral geniculate body
How does optic neuritis from MS affect vision?
often the first manifestation of MS, presents as sudden visual loss (blindness or scotoma) in one eye accompanied by pain in moving that eye; optic disc appears choked and swollen, similar to papilledema but unilateral
How can a pituitary tumor affect vision?
exerts pressure on the center of the chiasm from below and initially cause bilateral superior temporal quadrantanopsia and eventually bitemporal heteronymous hemianopsia
How can a temporal lobe tumor affect vision?
by compressing the inferior optic radiations that bend anteriorly around the tempora lobe (Meyer's loop) causes contralateral superior homonymous quadrantanopsia
How can a thrombosis or embolic occulusion of the posterior cerebral artery affect vision?
involvement bilaterally causes bilateral occipital lobe infarction and cortical blindness, this pt is unable to see, but pupillary light reflex is intact and no optic atrophy develops
What are the four main examination tests of auditory acuity?
bedside sound test; audiometry; weber test (tuning fork in midline); rinne test (tuning fork on mastoid process)
If the sound heard in the Weber test is not equal bilaterally where is the problem?
conductive deafness - vibration is heard louder in the deaf ear due to reduction of room or ambient noises which enhance the bone conduction; or Nerve deafness - the vibration is louder in the normal ear because air and bone conduction are lost in the deaf ear
What is Nylen-Barany or Dix-Hallpike maneuver?
method of examining vestibular function by tilting a supine head 45 degrees below flat and rotating it sideways 45 degrees and observing if nystagmus results if it is present then the posterior semicircular canal on the lowered side is over sensitive
What is conductive deafness?
a lesion between the environment and the receptors (ossicle lesion, impacted cerumen); results in low tone hearing loss
What is sensorineural deafness?
a lesion at or proximal to the organ of Corti (often due to noise damage or drug toxicity) results in high tone hearing loss; if severe or complete unilateral sensorineural deafness then likely from a CNVIII lesion
What is labyrinthitis?
usually from a viral infection or inflammation; causes severe vertigo, impaired hearing, nausea, and vomiting which subside spontaneously; gait ataxia, nystagmus and hearing loss
What is Meniere's disease?
due to the membranous labyrinth swelling and rupturing causing there to be intermixing of the endolymph and perilymph which impairs receptor function; is progressive and evetually leads to compete deafness; symptoms include periotic vertigo, tinnitus, and deafness, nystagmus, gait ataxia, and hearing loss
What is benign postional vertigo?
vertigo triggered by changes in head postion; due to oversensitive semicircular canal hair cells possibly from otolith degeneration and displacement; seen in older patients
What does the visual acuit of 20/200 signify?
the person can read the same Snellen chart letters at 20 feet that someone with normal vision would read at 200 feet
What disorders often cause a scotoma in one eye?
optic neuritis or partial retinal detachment in one eye
What are some common causes of vertigo?
inner ear infection, labyrinthitis, Meniere's disease, benign positional vertigo; or impaired blood flow in the vertebrobasilar circulation
What are some neurobehavioral syndromes that result from focal cerebral lesions?
aphasia; amnesia; apraxia; agnosia; frontal lobe syndrome, temporal lobe syndrome; parietal lobe syndrome; occipital lobe syndrome
What are the two types of amnesia?
anterograde (inability to learn new material, impaired recent memory); retrograde (inability to recall previously learned material (impaired remote memory) with relatively preserved attentiveness and cognitive function)
What are the three classifications of memory?
immediate memory (actually attentiveness necessary to register new information before short or long term memory storage); Recent (short term) memory recalling information after several minutes; Remote (long term) memory recalling past events several hours, weeks, years afterwards
What lesions produce amnesia?
usually bilateral interuption of the memory circuit of hippocampus →fornix→mammillary bodies→anterior thalamic nucleus
What are clinical examples of amnesia?
bilateral thalamic and mammillary body lesions occur in Wernicke-Korsakoff syndrome from alcoholism; bilateral hippocampal lesions may occur from anoxia or herpes simplex encephalitis
What is apraxia?
inability to conceptualize and perform a skilled learned act on command (may be spontaneously executed at another time); not caused by severe sensory, motor, or language deficits or inattention or lethargy
What are the two types of apraxia?
kinetic: impairs motor activities such as walking (gait apraxia) or dexterous movements usually from prefrontal lesions; Ideokinetic: impairs translation of concept into action usually from posterior hemipsheric (parietal) lesions
What is agnosia?
defective recognition of perceived stimuli caused by lesions in sensory association cortex; incorrect identification of familiar items soley by one sensory modality, the item may be correctly identified via different sensory stimuli
What are the two main types of agnosia?
visual agnosia (cannot recognize an object by sight but identified when touched); tactile agnosia (defect in recognition solely by touch which is a severe degree of asterognosis)
What symptoms can result from a frontal (prefrontal) lobe syndrome?
disinhibition, lack of concern, poor judgement; slow distractable motor and mental function; frontal lobe release signs (suck/snout reflex, rooting reflex, palmar/plantar grasp); gegenhalten or paratonia (rapidly move a limb lots of resistance/increased tone is observed, not seen when moved slowly); kinetic apraxia
What clinical deficits result from a bilateral lesion of the temporal lobe?
amnesia (hippocampal lesions); cortical deafness (auditory cortical lesions); Kluver-Bucy syndrome
What clinical deficits result from a unilateral lesion of the dominant temporal lobe? Non-dominant?
dominant: wernicke's aphasia; non-dominant: aprosodia
What cortical sensory deficits result from a parietal lobe syndome?
astereognosis; agraphesthesia; extinction of double simultaneous stimulation
What symptoms result from a non-dominant parietal lobe syndrome?
non-dominant: impairment of spatial relationships of body and surroundings (anosognosia: unawareness of hemiparesis or denial of that half of the body; dressing and contructional apraxias forms of ideokinetic apraxias involved with spatial confusion esp in dressing and construction)
What symptoms result from a dominant parietal lobe syndrome?
Gerstmann's syndrome (supramarginal or angular gyrus lesion): agraphia, right-left disorientation; dyscalculia (difficulty with calculations); finger agnosia (inability to identify one's fingers)
What is anosognosia?
unawareness of hemiparesis or in extreme cases, denial of that half of the body; often they are inappropriately cheerful; usually only occurs with R hemisphere lesions
What symptoms can result from a bilateral lesion of the occipital lobe? Unitlateral?
Bilateral: Anton's syndrome (denial or unawareness of cortical blindness); temporoccipital lesions may cause visual agnosia; Unilateral: color anomia (can't name colors)
What are some general symptoms that can result from diffuse or multiple cerebral lesion?
acute confusional state (delirium); dementia (organic brain disorder); combination of symptoms from various focal cerebral lesions
What is acute confusional state (Delirium)?
abrupt onset/short duration of changes in attention, levels of consciousness, and motor activity; impaired memory, language, thinking, and coordination; mood changes/ hallucinations; tremor, asterixis, myoclonus, ataxia, and dysarthria; potentially reversible with time; may be due to direct CNS insult (encephalitis, postictal) or indirect (metabolic/ drugs)
What is demetia?
progressive loss of previously acquired mental and intellectual ability, not mental retardation where the abilities were not achieved initially; may be persistent and progressive
What cognitive functions are affected by dementia?
memory (often first noted); orientation (to time, place, person, situation); intellect; judgement; language; personality and behavior (childlike or mean/paranoid)
What are potentially treatable/reversible causes of dementia?
chronic infections; metabolic and endocrine disorders; nutritional deficiencies; toxins and drugs; chronic subdural hematoma; intracranial tumor or abcess; normal pressure hydrocephalus; depression or pseudodementia
What are currently incurable/ irreversible causes of dementia?
multiple cerebral infarcts (possibly preventable); Alzheimer's disease (most common cause); Creutzfeldt-Jakob disease; rare degenerative diseases; AIDS
How do you clinically evaluate dementia?
detailed history with family and caregiver observations; neurological signs of focal lesion; neuropsychological testing; MRI/CT scan; blood and CSF testing
What is the epidemiology of Alzheimer's Disease?
most common cause of dementia (40-60%) in older americans; prevalence increases exponentially after 65 years of age to 50% of those over 85; slight female predominance; ~5-10% are familial inheritance (autosomal dominant)
What are the clinical features of Alzheimer's disease?
progressive symptoms, initially problems with memory, then intellect, aphasia, types of agnosia or apraxia; subsequent impaired judgement, change in personality, behavior and incontinence; terminal mute, vegatative/bed bound state; death usually occurs 2-15 years after onset of symptoms
What is the etiology of Alzheimer's disease?
neurodegenerative disease with progressive death of specific groups of neurons resulting from unknown factors (possible genetic or environmental factors); β-amyloid seems to play a crucial development of the dz, is a fragment of a larger transmembrane protein and has its gene on chromosome 21 (nearly all down's syndrome pts develop alzheimer's);
What pathology is involved with Alzheimer's disease?
decreased brain weight (due to atrophy of cerebral cortex esp amygdala and hippocampus) causes enlargement of ventricles (hydrocephalous ex vacuo); microsopic gliosis and neuronal loss of subcortical nuclei; histological amyloid or senile plaques and intraneuronal neurofibrillary tangles
Which subcortical nuclei degenerate in Alzheimer's disease?
cholinergic nucleus basalis of Meynert in basal forebrain (learning and memory); noradrenergic locus ceruleus in pons (depression symptoms); and serotonergic raphe nuclei throughout midline brain stem (depression symptoms)
What are amyloid or senile plaques?
diagnostic microscopic features of alzheimer's which consist of abnormal axonal endings associated with extracellular β-amyloid
What are intraneuronal neurofibrillary tangles?
microscopic features of alzheimer's which are insoluble tau protein in paired helical filaments esp in cortical layers 3 and 5; also found in other neurodegenerative diseases
How is Alzheimer's disease clinically diagnosed?
only can be diagnosed with certainty on autopsy; if no hx of rapid progression or stroke-like episodes and excluded all other treatable types of dementia then Alzheimer's is assumed: chomosome testing, CT,MRI,EEG, CSF, blood tests, neuropsychological tests to rule out other causes
What is the treatment of Alzheimer's?
no curative treatment available; limited transient symptom benefit by enhancing central cholinergic system with inhibitors of ACh esterase (tacrine, donepezil, rivastigmine); estrogen and NSAIDs to delay onset/progression; sedatives for behavioral problems
What is stroke?
a general term for a focal neurological deficit of sudden onset caused by cerebrovascular disease, which can improve over time; can be an ischemic infarct or hemorrhagic
What are the artherosclerotic changes which can cause strokes?
subintimal lipid deposition, smooth m. proliferation, and fibrosis leading to atheromas or arterial plaques esp at bifurcations of large arteries and regions of more turbulent blood flow; these can narrow/occlude the arterial lumen or ulcerate and embolize downstream
What are the perforator or lenticulostriate arteries?
small arteries from the basilar and proximal anterior and middle cerebral arteries which supply deep structures of basal ganglia, internal capsule, thalamus, corona radiata
What is a thrombosis?
blocking of an artery at the site of the forming arterial plaque (atheroma)
What is an embolus?
a portion of an arterial plaque which ulcerates and breaks free to block a more distal, narrower vessel
What are three sources of collateral circulation for an occlusion of the cervical internal carotid artery?
basilar artery flow from the posterior cerebral through the posterior communicating; external carotid artery can reach via retrograde flow through the opthalmic artery; contralateral internal carotid. Via the anterior cerebral and the anterior communicating artery
What is a transient ischemic attack (TIA)?
reversible focal neurological deficit lasting 24 hr or less (10-20 min usually), due to embolus from arterial or cardiac source comprised of clot, platelets, fibrin, or cholesterol plaque which obstructs a large artery in the brain and disintegrates, reestablishing blood flow in several minutes, preventing ischemic death of neurons
What are symptoms of a TIA in the carotid territory?
amaurosis fugax (monocular blindness, darkening of one eye or retinal ischemia); hemispheric symptoms such as aphasia and hemiparesis
What are symptoms of a TIA in the vertebrobasilar territory?
brainstem symptoms (diplopia); cerebellar symptoms (ataxia); visual cortex (homonymous hemianopsia)
What can be some causes of the TIA within the symptomatic artery?
atherosclerotic stenosis or ulcerated plaque (common); nonatherosclerotic disease (traumatic/spontaneous arterial dissection; vasculitis; fibromuscular dysplasia)
What can be some nonarterial sources of an emboli to cause a TIA?
cardiac sources (MI; nonrheumatic atrial fibrillation; valvular lesion/endocarditis; right to left shunts passing a DVT into cerebral circulation); hypercoagulable states (sickle cell anemia; polycythemia vera)
What is an ischemic infarct?
a persistent focal neurological deficit caused by ischemic death of neurons in the territory of the occluded artery due to local thrombosis or more distant embolis; symptoms may gradually improve
What are the typical syndromes of a cortical ischemic infarct?
hemiparesis (face/arm>legs then MCA; legs>face/arm then ACA); aphasia; cortical sensory deficits; homonymous hemianopsia
What are the typical syndromes of a cerebellar or brain stem ischemic infarct?
cerebellar hemispheral syndrome (deficits ipsilateral to infarct); weber and wallenberg syndromes
What are possible causes of large vessel occlusion leading to an ischemic infarct?
atherosclerotic thrombosis of an arterial bifurcation, arterial embolus, nonatherosclerotic vascular disease; cardiac embolus; hypercoagulable state
What are possible causes of small, penetrating vessel occlusion leading to an ischemic infarct?
lacunar infarcts (internal capsule, corona radiata, basilar pons, or thalamus) often due to HTN, diabetes or old age; hypercoagulable state
What are syndromes associated with small artery ischemic infarct?
pure motor hemiplegia; pure sensory stroke; ataxic-hemiparetic syndrome; clumsy hand-dysarthria syndrome; occasionally no symptoms
What are methods of preventing future TIA or ischemic infarction?
control of atherosclerotic risk factors (HTN, heart disease, DM, high cholesterol, smoking); carotid endarterectomy (for symptomatic cervical internal carotid stenosis>70%); anticoagulants (heparin/warfarin to prevent future cardiac emboli esp with atrial fib); antiplatelet drugs
What should be done in the management of an acute ischemic infarct?
clinical exam; CT or MRI (to ID territory involved and R/O hemorrhage or mass); control BP and blood glucose; thrombolytic agents (tPA to dissolve clot <3hrs from onset after which there is ↑risk of bleeding); monitor cerebral edema; stroke rehab
What are usually the preventative therapies for lacunar infarcts?
antiplatelet medications and control of vascular risk factors
What pathology is seen in cortical infarction?
gross appearance is soft/swollen with poor gray-white matter distinction, hyperemic, later shrinking of affected cortex and white matter; microscopically ischemic neurons shrink and become pink by 12-36 hrs; macrophages enter btw 3-10 days; cyst formation occurs with astrocytes at periphery; layer 1 of cortex is intact with leptomeninges
What are the etiological causes of cerebral hemorrhage?
HTN (most common cause); head trauma; rupture of congenitally abn blood vessels (arteriovenous malformation/aneurysm); bleeding within an ischemic infarct; bleeding in brain tumor; systemic bleeding disorder; illicit drugs; cerebral amyloid angiopathy in the elderly
What are the presenting symptoms of a cerebral hemorrhage?
severe HA, early stupor or coma (due to ↑intracranial pressure); localizing signs or seizures
What is a cerebral hemorrhage?
when a high pressure arterial blood vessel of the brain ruptures into the parenchyma and causes edema; also shifting or herniation can result due to ↑intracranial pressure; impaired circulation due to pressure/edema causes focal ischemia
What is done to diagnositically evaluate a cerebral hemorrhage?
abn coagulation tests; CT/MRI (esp CT w/o contrast shows recent hemorrhage as bright white); angiography (if abn blood vessels suspected)
What is the therapy for cerebral hemorrhage?
management of medical complications and cerebral edema; surgery (esp if deteriorating level of consciousness and superficial, nondominant hemispheric hemorrhage; cerebellar hemorrhage to prevent tonsilar herniation; AVMs)
What pathology is seen in cerebral hemorrhage?
dark red clot with surrounding edema; clot liquefies, edema resolves and cyst or slit with brown-stained periphery persists
What is a subarachnoid hemorrhage?
bleeding into the subarachnoid space caused by trauma (most common overall); ruptured congenital berry aneurysm (most common nontraumatic); subarachnoid blood secondary to cerebral hemorrhage; systemic bleeding disorders
What is a berry aneurysm?
thinned out-pouchings at an arterial bifurcation (weak point); it enlarges over time and increases its risk of rupture; most commonly located in the circle of Willis
What are the clinical syndromes of berry aneurysms?
asymptomatic; severe headache, nuchal rigidity, meningeal signs from tiny warning leak; mass effect (with/without rupture) often causing third nerve palsy; massive subarachnoid hemorrhage with sudden onset of coma or death
How are subarachnoid hemorrhages from ruptured aneurysms diagnosed and managed?
CT (to visualize hemorrhage); LP to verify if minor; angiography to localize hemorrhage; surgical clipping or endovascular coil occlusion to prevent rebleeding; hemodilution and induced HTN; Nimodipine (Ca channel blocker)
What is the most common location of congenital berry aneurysms?
anterior circulation of the circle of willis
What is the most common cause of cerebral hemorrhage and what are the typical sites involved?
HTN; usually involves the putamen, caudate, thalamus, corona radiata, pons, and cerebellum
What is a tumor?
an uncontrolled, unregulated growth of a body tissue which may retain function or resume a more primative state; contributing factors include loss of a tumor suppressor gene or inappropriate expression fo oncogenes which enhance mitosis
What is a primary brain tumor?
a tumor which arises within the CNS (glia, neurons, or the meninges); very rarely spread as metastases to distant sites
What is a secondary brain tumor?
metastatic tumor spread to CNS from a non-CNS source; may extend from vertebral or skull metastases; spread distinctly through blood or lymphatics; often from lung, breast or melanoma;
What are malignant brain tumors?
gliomas; metastases; they generally grow fast and spread rapidly; microscopically are less differentiated and invade normal surrounding tissue
What are benign brain tumors?
menigiomas, pituitary adenomas, neurinomas/scwannomas; generally slow growing; microscopically differentiated, encapsulated and segregated from normal surrounding tissue
Where are primary brain tumors most commonly found in children?
infratentorial (cerebellar medulloblastoma or astrocytoma)
Where are primary brain tumors most commonly found in adults?
Does the malignancy or benign nature of a brain tumor important?
not as much as the location of the tumor which regardless of its malignancy be surgically inaccessible and in a vital area cause death
What are some general symptoms of a brain tumor?
focal neurological deficits (develop more slowly than stroke); seizures; increased intracranial pressure (tumor edema, shifting brain, obstruction of CSF) causes HA, nausea, vomiting, drowsiness, or fatigue; general impairment of mental function (forgetfulness, irritability, poor concentration, changes in mood or behavior)
What are some malignant primary brain tumors?
astrocytoma, ependymoma, medulloblastoma, oligodendroglioma
What is an astrocytoma?
tumor from the astrocytes, greater the grade of malignancy the worse the prognosis; glioblastoma multiforme is the most malignant type
What is an ependymoma?
tumor from the ependymal cells lining the ventricles; most often occur in the posterior fossa in children and obstruct the 4th ventricle; can develop in the filum terminale and central canal of the spinal cord in adults
What is a medullopblastoma?
a tumor from the neuroepithelial roof of the 4th ventricle in the cerebellum
What is an oligodendroglioma?
tumor from the oligodendrocytes which often involves the frontal lobes of adults
How are primary brain tumors treated?
complete surgical excision (better prognosis); radiation therapy or chemotherapy extends survival
What are characteristics of a metastatic brain tumor?
grow in the gray-white matter subcortical junction; commonly multiple in number with regular borders
What are some benign primary brain tumors?
meningiomas, pituitary adenomas, acoustic neuromas
What is a meningioma?
arise from the arachnoid (parasagittal falx, cerebral convexities, sphenoidal ridge, olfactory groove); most common benign brain tumor, best prognosis with complete resection
What is a pituitary adenoma?
symptoms include hormonal excess or dysfunction/ optic chiasm visual deficits
What is an acoustic neurinoma?
neuroma or schwannoma at the cerebellopontine angle often arising from the nerve sheath of the vestibular nerve; preservation of hearing and facial nerve function posisble with surgical resection
What is a direct vs. indirect alteration of an ion channel?
direct: a genetic mutation of the channel protein; indirect: modulation of the ion channel protein (phosphorylation, interaction with subunits; inhibitory protein), intoxication/poisoning; autoimmune diseases
What are some ion channel diseases?
gene mutation: defective channel protein and/or accessory protein not properly expressed; autoimmune dz.: MG, lambert-eaton syndrome; neuromyotonia (Ig against voltage-gated K channels); pleotropic effects: mutant gene coding for protein kinase that doesn't directly relate to the voltage dependent Na channel
What is myotonia?
series of involuntary contractions of skeletal m. following one ore more voluntary contractions; repetitive APs are automatically generated after a train of voluntary APs (hyperexcitability); caused by Cl and/or Na channels
What two channels have been found to be involved with myotonia?
Na and Cl channels
How do Cl channel mutations cause myotonia?
normally after an AP K accumulates in the T-tubules and depolarize the cell membrane and causes a loss of the resting potential; the Cl channels counteract this by a strong Cl influx to maintain the resting potential; with and abnormal Cl channel the resting membrane potential is brought closer to threshold and allows for Na channels to open spontaneously →non-voluntary APs
Are Cl channel problems due to a change in the # of ions crossing the channel or the gating of the channel?
gating of the channel and whether or not it opens, once it opens they function normally
What problems can cause abnormalities in the CLC-1 skeletal muscle Cl channels?
dominant myotonia congenita (single point mutation); recessive myotonia congenita (many distinct point mutations, sometimes dysfuncitonal Na channels contribute)
What are causes of myotonia related to Na channel mutations?
human paramyotonia congenita; hyperkalemic periodic paralysis; due to abnormal activation of Na channels, they open/close several times for every AP
What is the mutation that causes malignant hyperthermia?
mutation of the Ca-release channels in the skeletal m. SR. this causes an increase in the release of Ca, the generation of lots of ATP, heat, and CO2.
What is skeletal m. hypokalemic periodic paralysis?
surge of muscle weakness and relaxation with a low serum K which begins a few hours after a high carbohydrate meal and can last 4-24 hrs, due possibly to two mutations in the skeletal m. L-type Ca channels
What is lambert-eaton syndrome?
autoimmunce dz caused by Igs against voltage activated Ca channels in the presynaptic terminal preventing their function and the release of Ach; causes muscle weakness and fatigue
What is familial hemiplegic migraine?
rare autosomal dominant form of migraine which has typical migraine symptoms and paralysis of one side of the body and occasional cerebellar atrophy; often associated with mutations of the gene that codes P/Q type Ca channels (change in volume of Ca through the channel) possibly facilitates cortical spreading depression
What is episodic ataxia type 2?
typical migraine symptoms and paralysis of one side of the body always with cerebellar atrophy; often associated with mutations of the gene that codes P/Q type Ca channels (change in volume of Ca through the channel) possibly facilitates cortical spreading depression
What is episodic ataxia type 1?
myokymia: autosomal dominant disorder characterized by periodic attacks of motor imbalance, involuntary tremor, and incoordination due to point mutation in K outward rectifier channel and promotes hyperexcitability
What can cause elevated intracranial pressure?
focal lesion (bleed, tumor, seizure focus, vascular lesion, AVM); generalized process (hydrocephalous)
What are two classifications of hydrocephalous?
communicating: failure of absorption by arachnoid villi (due to meningitis or infection that scars arachnoid villi shut); Non-communicating: obstruction of flow at cerebral aqueduct (ie due to ventricular hemorrhage where blood irritates and scars the aqueduct closed)
What ion has a large concentration within the CSF fluid?
Cl, choroid plexus puts lots of chloride (more than serum) and glucose into CSF
What are some of the treatments of hydrocephalous?
ventriculostomy (hole through frontal lobe or occipital lobe to drain fluid); shunts often to peritoneal cavity with valve and antisyphon device
What is the usual clinical presentation of hydrocephalous?
headache, lethargy, loss of appetite/vomiting; later stages: setting sun eyes due to pressure on tectum
What percentage of the population has an intact circle of willis?
What causes ring enhancing lesions?
(Magic Dr. L): mets, abcess, glioma, infarct, contusions, demyelinating lesions (MS), resolving hematoma, lymphoma
What drug is often administered to open the BBB and increase the delivery rate of drugs to the CNS?
mannitol (opens the BBB for ~20 mins)
How long can normal cerebral function continue after cerebral ischemia? When does irreversible damage begin to occur?
8-10 seconds; irreversible damage after 6-8 min of ischemia
What is the order of sensitivity among cell types of the CNS?
neurons (most sensitive)> oligodendrocytes > endothelial cells>> astrocytes (not very sensitive)
What regions of the brain are the most sensitive areas to ischemia?
pyramidal cells of the hippocampus; purkinje cells of the cerebellum; medium sized neurons of the striatum and deep cortical neurons
What regions of the brain undergo necrosis with low perfusion pressures?
watershed or border zone infarcts in regions btw arterial territories (btw MCA and ACA/ btw MCA and PCA)
What is global ischemia of the brain?
due to heart attack, hemorrhage, and septic shock that leads to low perfusion of the brain; ischemic areas show eosinophilic neurons, laminar necrosis (cortical deep layers 3-6, upper layers are perfused by middle meningeal artery)
What are the three causes of focal ischemia in the brain?
ischemic infarct; hemorrhagic infarct; lacunar infarct
What is the most common cause of ischemic infarct and where does it occur?
75% are due to atherosclerosis and secondary thrombosis; 10% due to embolis; commonly occur in MCA (large vessel disease)
Who is most likely to get an intraventricular hemorrhage?
premature infants <30 wks; hemorrhage of the germinal matrix next to ventricle, instantly fatal
What are common characteristics of all neurodegenerative diseases?
selective vulnerability of specific neurons in one brain area or neuronal systems; all are progressive and irreversible; dz that affect similar brain regions usually have similar symptoms
What are some distinguishing characteristics that can be used to identify different neurodegenerative diseases?
patterns of hertiability; time course; first presenting symptom; microscopic features
Which neurodegenerative diseases primarily affect the cerebral cortex?
Alzheimer's dz; Pick's dz; Frontotemporal dementias
Which neurodegenerative diseases primarily affect the basal ganglia?
huntington's disease; idiopathic parkinson's disease; progressive supranuclear palsy
Which neurodegenerative diseases primarily affect the cerebellum and spinal cord?
multiple system atrophy; friedreich's ataxia; spinocerebellar ataxias
Which neurodegenerative diseases primarily affect motor neurons?
amylotrophic lateral sclerosis (ALS); spinal muscular atrophies
What are benign epithelial tumors called?
What are malignant epithelial tumors called?
What are malignant mesenchymal lesions called?
What are primary (glial) brain tumors called?
What is the second most common cause of cancer in children?
primary CNS neoplasms
How do primary brain tumors present?
seizures, focal deficits, intracranial pressure, hydrocephalus, nausea/vomitting
What features are characterisitc of glioblastoma (GBM)?
palisading necrosis; vascular endothelial proliferation
What genetic mutations are more common in primary glioblastoma (GBM)?
What genetic mutations are more common in secondary glioblastoma (GBM)?
p53, RB1 hypermethylation, loss of 19q
What are oligodendrogliomas characterized by?
chicken wire vessels; perinuclear clearing (fried egg cell)
What is the most significant prognosis factor in astrocytomas?
What frequent genetic change found in oligodendrogliomas indicates response to treatment?
deletion of 1p and 19q
Which type of vessel is associated with malignancy?
vessels with endothelial proliferation
What type of vessel is seen in low grade tumors like pilocytic astrocytomas and schwannomas?
hyalinized vessels
What type of vessel is seen with ependymomas?
What are characteristics of ependymomas?
6-9% of primary CNS lesions; usually children (30% of primary peds tumors); often infratentorial; in the spine is older pt (20-40) and assn with NF-2; perivascular pseudorosettes
What are characteristics of oligodendrogliomas?
7-10% primary CNS tumors; equal M:F; 30-50yo; frontal lobe; often present with seizures or have hemorrhage; sensitive to chemo; have chicken wire vessels; dense nodular areas; subpial accumulation of cells; perinuclear clearing; satellitosis
What are characteristics of pilocytic astrocytoma?
mostly in kids; found in cerebellum, optic nerve/chiasm, hypothalamus, diencephalon, temporal lobe; cerebral in adults; assn with NF1 (esp optic); have long hair-like cells, rosenthal fibers, eosinophilic granular bodies; small hyalinized vessels; benign can develop into a glioblastoma
What are characteristics of a medulloblastoma?
5% of CNS neoplasms; 20% of peds; usually arise in vermis/4th ventricle; chemotherapy/radiation to treat; angular nuclei, homer-wright rosettes
What are characteristics of a meningioma?
incidence increases with age; 15% of intracranial/25% of intraspinal lesions; 10% of pts have multiple; intracranial 3F:2M; intraspinal 10F:1M; oval nuclei, syncytium, whorl shapes, hyalinized vessels, fibrous
What are characteristics of a schwannoma?
8% of intracranial neoplasms; 4th-5th decade; vestibular portion of CNVIII common; sometimes CNV; sensory roots if spinal; club shaped nuclei, hyalinized vessels, verocay bodies,
What tumor can have rosette-like structures?
ependymoma; medulloblastoma; schwannoma
What is histological feature is only found in benign tumors?
hemacitarin: death of RBC by macrophages; malignant tumors outgrow their blood supply and would never have this
What are characteristics of pituitary adenomas?
genetics: MEN 1; 10-15% of intracranial neoplasms; 3-6th decade; 3F:1M; hormone symptoms or mass effect symptoms; round discohesive cells, prolactin amyloid, polarization,
What are characteristics of CNS metastases?
15% of intracranial neoplasms; 30% of disseminating CA will have brain mets, 6-7th decade; 50% from lung; disproportionate amt of melanomas sent mets to brain, sharp border btw tumor and normal brain,
What are the most common primary CNS tumors in adults?
astrocytomas and meningiomas
What are the most common primary CNS tumors in children?
medulloblastomas and pilocytic astrocytomas
What causes tetanus?
exotoxin Clostridium tetani, anaerobic contaminated wounds or injuries, presymptomatic incubation of 3wks; exotoxin binds to cortical, brainstem or spinal cord interneurons and prevents GABA release, disinhibiting motor neurons
What are the two locations/extents of tetanus?
localized: due to retrograde axonal transport of exotoxin near the wound (muscle spasms); generalized: spread of exotoxin through bloodstream
What are the signs and symptoms of tetanus?
painful spasms of the jaw (trismus); face (risus sardonicus) and arching back (opisthotonus); difficultly swallowing and breathing, seizures
What is the treatment for tetanus?
ICU care: mechanical ventilation, neuromuscular blockade, sedation, anticonvulsants for seizures, tetanus Igs (neutralize remaining exotoxin); antibx for wound infection
What causes botulism?
exotoxin Clostridium botulinum, in anaerobic environments (canned food, wound infection), exotoxin binds to presynaptic nerve terminal and prevents ACh release at LMN and parasympathetic neurons leading to paralysis
What are signs and symptoms of botulism?
begin 12-48 hrs after ingestion, ptosis, diplopia, pupillary paralysis, dysphagia, facial and limb weakness, respiratory paralysis
How is botulism diagnosed?
clinical picture, bioassay of exotoxin in food, blood, or feces; EMG, elimination of other paralysis possibilites
What is the treatment for botulism?
equine derived antitoxin (20% risk of allergic rxn); guanidine to facilitate ACh release, supportive care
What are CNS symptoms from opiates, stimulants, phencyclidine (PCP)?
variable mood/behavior changes, altered consciousness, hallucinations, seizures, respiratory depression, secondary head trauma or systemic illness
What should be considered when a stroke occurs in a young patient?
drug-related stroke due to increased vasoconstriction or HTN from amphetamines, PCP, LSD, or cocaine leading to acute cerebral infarct/ hemorrhage
What are some environmental or occupational toxins?
heavy metal poisoning (lead, arsenic, mercury); chemical spills/contaminations; carbon monoxide
What are some symptoms of carbon monoxide poisoning?
early headache, vomiting, visual blurring; later coma, seizures, and cardiopulmonary arrest; causes venous stagnation, edema, and hemorrhages in CNS; survivors may develop memory and cognitive deficits and rarely parkinsonism
What is the treatment for carbon monoxide poisoning?
100% oxygen by mask or hyperbaric chamber
What are the progressive stages of alcohol withdrawl syndrome?
early hypersympathetic (tremulous diaphoresis, tachycardia, jittery); 12h-3days generalized tonic-clonic seizures may occur; 3-4 days delerium tremens (increased motor/autonomic activity, confusion, hallucinations, can be fatal due to infection, trauma, hyperthermia)
What are the treatments for alcohol withdrawl syndrome?
sedation and seizure control (benzodiazepines); hydration, metabolic care, thiamine supplement
What syndromes can result from chronic alcohol abuse?
peripheral neuropathy, alcoholic myopathy, head trauma, Wernicke-Korsakoff syndrome, alcoholic cerebellar degeneration, central pontine myelinolysis, alcoholic dementia
What is wernicke;s encephalopathy?
nystagmus, ophthalmoplegia, gait ataxia, and confusion which is an acute/reversible condition due to thiamine deficiency seen in chronic alcoholics
What is korsakoff's psychosis?
a chronic amnesic syndrome sometimes with confabulation, due to petechial hemorrhages and gliosis in mammillary bodies, fornix, and walls of the third ventricle
What is meningitis?
inflammation of the meninges from infection in bloodstream, adjacent infection (otitis, sinusitis); or infection in subarachnoid space
What are signs and symptoms of acute meningitis?
fever, malaise, lethargy, headache, nausea, and vomiting; impaired consciousness (progressing to stupor or coma); nuchal rigidity; meningeal irritation
What are the two types of meningitis and course that each takes?
Bacterial (severe, fulminant, potentially treatable with antibx, fatal if not treated early); Viral (benign, nonfatal, not treatable)
What is found in the CSF in a pt with bacterial meningitis?
polymorphonuclear WBC and low glucose
What is a sign of meningococcal meningitis?
petechial rash
How is bacterial meningitis treated?
broad spectrum antibiotics (ceftriaxone, with vancomycin or with ampicillin) initially; change to specific antibiotics once the organism is identified from CSF
What are some secondary effect/complications from bacterial meningitis?
hydrocephalous, meningoencephalitis (inflammation/edema of cortex); infarction from thrombosis of inflamed vessels; risk of deafness
What is chronic meningitis?
mild HA or confusion without meningeal signs due to variety of organisms (tuberculosis, fungus, syphilis, parasites) that produce symptoms over weeks to months esp in elderly, malnourished and immunosuppressed
What is encephalitis?
the primary infection or inflammation of the brain usually from a virus
What are signs and symptoms of encephalitis?
evolution over hours to days; high fever and HA, changes in behavior, consciousness (possibly stupor or coma); seizures or focal deficits, some symptoms may be similar to meningitis but focal deficits are unique
How are the viruses that cause encephalitis often transmitted?
arthropods (ticks and mosquitos, seasonally); ingestion (polio); inoculation (rabies); inhalation (herpes simplex)
What are unique characteristics of Herpes simplex encephalitis?
nonepidemic and nonseasonal, predilection for inferior frontal, medial temporal lobes (leads to aphasia, behavioral changes and memory impairment); mortality is high (40-70% untreated); now treated with acyclovir to reduce mortality to 20%
How is viral encephalitis diagnosed?
CSF similar to viral meningitis (some WBC, normal to high protein); detection of viral DNA in CSF from PCR, MRI showing regional inflammation, serum antibody titers to suspected viruses
How is viral encephalitis treated?
ICU care, sedation and control of intracranial pressure, anticonvulsant therapy, acyclovir antiviral drug
What is Polio?
infection of motor neurons in brainstem and spinal cord causing weakness, typically asymmetrical and atrophy of one limb, Postpolio muscular atrophy due to loss of motor nerve terminals may occur 10-40y after initial infection
What is varicella zoster?
reactivation of varicella in dorsal root ganglia, leading to vesicular rash and severe neuralgic pain along a dermatome
What are prions?
infectious proteins which cause conformational changes in normal proteins, cause transmissible spongiform encephalopaties
What is Creutzfeldt-Jakob disease?
rapid, progressive untreatable type of dementia; may have corticospinal tract, extrapyramidal, cerebellar, or LMN signs too; myoclonus; causes spongiform changes in neurons and astrocytes leading to neuron loss without inflammation
What is bovine spongiform encephalopathy?
mad cow disease, transmissible form of Creutzfeldt-Jakob disease
What is an intracranial abcess?
localized, encapsulated infection (usually bacterial) from blood borne or adjacent spread located within brain or outside brain (epidural, subdural)
What are signs and symptoms of an intracranial abcess?
systemic infection, HA, meningitis, seizures, focal signs depend on location of the lesion(s)
How is an intracranial abcess diagnosed?
CT or MRI scan with or without contrast
How is an intracranial abcess treated?
surgical excision, antibiotics
What is AIDS?
HIV-1 infection that destroys T4 helper lymphocytes creating inadequate immune responses and constitutional symptoms
What are constitutional symptoms of AIDS?
fatigue, weightloss, fever, diarrhea
What are neurological complications of AIDS?
varied syndromes occur at different stages: acute, aseptic meningitis (may precede infections); Lymphoma, progressive multifocal leukoencephalopathy (PML: due to papovavirus, patchy demyelination of CNS white matter); cerebral toxoplasmosis, cryptococcal meningitis, cytomegalovirus retinitis or encephalitis
What are possible mechanisms for the neurological complications of AIDS?
direct viral infection, damage by products of infected cell lysis, autoimmune attack
What is the function of the secondary visual cortex (V2, V3 and BA 18,19)?
afferents from V1 and thalamic lateral geniculate and pulvinar, efferents to the superior colliculus and pretectum to generate visual tracking; a lesion here causes an inability to recognize familiar objects or persons, without visual field defects (prosopagnosia)
What system leads to the "what" processing from visual fields?
Parvo system of the lateral geniculate, high resolution that leads to the id of complex objects and recognition of faces
What system leads to the "where" processing from visual fields?
Magno system of the lateral geniculate, low resolution, but movement sensitive, leads to awareness of where stimulus is and how fast it is moving and direciton of movement
What are the subdivisions of the hypercolumns within the primary visual cortex?
two Ocular dominance columns (with cells responding more strongly to the R or L eye); Orientation pinwheels (cells respond more strongly to particular orientations of visual stimuli)
Which cortical layer of the striate cortex is monocular? Which is binocular?
monocular: layer IV because it receives input from only one eye; binocular: all other layers because they receive input from both eyes with some preference to the eye of its named ocular dominance field
What is achromatopsia?
bilateral damage to the visual area V4 which causes loss of color perception
What kind of emotional reaction often occurs in patients with Left hemisphere lesions?
carastrophic reaction: great anxiety, worry, fear of loss of control, avoidance of situations where their disability makes them unable to perform; very mild neglect of right side may result
What kind of emotional reaction often occurs in patients with Right hemisphere lesions?
inappropriately cheerful, making light of the severity of their deficits or even profound neglect of the left side of space (both presently and imagined) and their own body
What is the Lewy Body variant of alzheimer's disease?
an overlap btw alzheimer's and parkinson's which has lewy bodies rather than neurofibrillary tangles within the brain and pt present with some parkinsonian symptoms, they still must have amyloid plaques
What is the order of cortical impairment in Alzheimer's disease?
amygdala and hippocampus→ posterior parietal cortex→frontal lobe (sensorimotor strip and cerebellum are preserved until very late)
Where do the neurofibrillary tangles predominate?
most numerous in association areas of the neocortex and in the limbic system; large neurons of layers 3 and 5 of the neocortex are most vulnerable
Does α or β secretase cleave the progenitor of Aβ to prevent plaque formation?
α secretase does; possibly modification of β secretase will prevent the formation of excessive beta amyloid
What chromosomal mutations are implicated in familial forms of alzheimer's disease?
chromosome 21 (gene of β-APP); chromosomes 14 and 1 (Presenilin 1 and 2 respectively, splicing proteins of the Aβ precursor); ApoE (allele e4, lipid metabolism)
What is Pick's disease?
a rare form of dementia where pt presents with aphasia rather than memory loss but later have dementia in the disease
What are the pathological features of Pick's disease?
primarily frontal lobe atrophy with neuronal loss, extensive gliosis (w/ or w/o ballooned neurons); intraneuronal accumulations called Pick bodies (formed from abn folded tau proteins), No amyloid plaques, No neurofibrillary tangles
What are frontotemporal dementias?
often due to mutation of the tau protein on chromosome 17, abn tau and neurofibrillary tangles in grey and white matter of frontal and temporal cortex, may have parkinsonism due to abn tau in substantia nigra
What pathology is seen in Huntington's Disease?
small brains with atrophy of the caudate and putamen greater than cortical atrophy, microscopically gliosis and loss of medium sized neurons (large neurons are spared)
What pathology is seen in Parkinson's disease?
pallor of the midbrain substantia nigra with microscopic loss of neuromelanin cells, gliosis, extraneuronal pigment deposition and intraneuronal cytoplasmic inclusions (Lewy Bodies)
What is progressive supranuclear palsy?
rare disease usually affecting males btw 50 and 70 with parkinsonism, neck rigidity, gait disturbances, opthalmoplegia, and mild dementia; do not benefit from L-dopa therapy
What pathology is seen in progressive supranuclear palsy?
pallor of substantia nigra, atrophy of the globus pallidus, subthalamic nuclei and dentate nuclei of the cerebellum. Microscopic cell loss, and globose nuerofibrillary tangles
What is multiple system atrophy?
sporadic disorder with features of parkinsonian symptoms, cerebellar ataxia, and shy-drager; gait disturbances, that are progressive
What pathology is seen in multiple system atrophy?
atrophy of the putamen, substantia nigra, cerebellum, pons, and olivary nuclei; microscopic neuronal loss, gliosis, and glial cytoplasmic inclusions (α-synuclein) in oligodendrocytes
What is Friedreich's ataxia?
most common form of hereditary ataxia due to autosomal recessive inheritance of GAA repeat in first intron of frataxin gene of chromosome 9; often have associated anomalies of the heart
What pathology is seen in Friedreich's ataxia?
degeneration of the spinal cord posterior columns, spinocerebellar and to a lesser extent corticospinal tracts
What is usually the cause of death of pts with ALS?
pneumonia due to weakness of pulmonary musculature
What pathology is seen in amyotrophic lateral sclerosis?
discoloration of the corticospinal tract, atrophy of the ventral roots and muscular atrophy
What are the two forms of spinal muscular atrophies?
werdnig-hoffmann disease (SMA type I, floppy baby); Kugelberg walander disease(SMA-type II)