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71 Cards in this Set
- Front
- Back
What are the four major demyelinating diseases? |
1) multiple sclerosis (MS)
2) neuromyelitis optica (NMO)
3) acute disseminated encephalomyelitis (ADEM)
4) central pontine myelinolysis (CPM) |
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What is the pathophysiology behind MS? |
-autoimmune disease in which the body makes Ab targeted against myelin basic protein (MBP)
-the Ab destroy myelin and short circuit the nervous system
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What can repeated bouts of MS cause? |
axon breakage which may not heal |
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In what group of people is MS more common? |
-white (over black) females (over males)
-both 2:1 ratios |
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What is the triad of symptoms for MS? |
1) optic neuritis -visual changes, diplopia -optic nerve may light up white on T1 MRI (should be black)
2) transverse myelitis -paralysis, incontinence, sensory loss -spinal cord may light up white on T1 MRI (should be black)
3) ataxia, vertigo |
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What are the radiological findings of MS? |
multiple white matter lesions that change over time (have to see a series of images) |
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How may you diagnosis MS? |
-mostly a diagnosis of exclusion; see multiple lesions in time and space
-oligoclonal bands in CSF |
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What is the problem with trying to diagnose MS with oligoclonal bands in CSF? |
-terrible sensitivity and specificity
-even if positive, doesn't necessarily mean patient has MS |
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What is the differential diagnosis for MS? |
1) cerebrovascular disease
2) other autoimmune demyelinating diseases
3) viral encephalitis
4) neoplasms |
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What is the geographical distribution of MS and what does it suggest? |
-more common in northern temperate zones (even in northern part of U.S.)
-suggests a virus |
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What are the 3 main patterns of MS seen in the patient population, and what are the respective percentages of the population in each pattern? |
1) relapsing-remitting - 70% -may eventually lead to secondary progressive -never quite get back to normal because of axonal breakage
2) benign relapsing-remitting - 10% -lucky
3) primary progressive - 20%
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How can you predict the pattern of MS for any given patient? |
hard to do, not really a good way to do it - just have to follow them for awhile and track progress |
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What are the two big categories of therapy for MS? |
1) maintenance/prevention
2) relapses |
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What are the medicines for maintenance/prevention of MS? |
1) Avonex (interferon beta-1a)
2) Betaseron (interferon beta-1b)
3) Extavia (interferon beta-1b)
4) Rebif (interferon beta-1a) |
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What are the medicines for dealing with relapses of MS? |
1) oral prednisone
2) IV methylprednisolone |
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Why and how do we hit relapses of MS so aggressively? |
steriods - trying to prevent axonal breakage |
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What 2 things do we see in MS histology? |
1) luxol fast blue stain - loss of myelin indicated by light areas in the white matter
2) higher power magnification - lots of perivascular lymphocytes, macrophages, and plasma cells |
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What is tumefactive MS? |
a severe attack of MS that one would think is probably brain cancer - resembles a glioblastoma radiologically and histologically |
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How can we distinguish tumefactive MS from a glioblastoma? |
molecular diagnostics |
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What is the other name for neuromyelitis optica? |
Devic's disease |
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What other disease does NMO very closely resemble? |
MS |
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What is the difference in NMO and MS demographically? |
NMO affects blacks > whites |
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What is the difference in the molecular cause behind NMO vs. MS and what does that result in clinically? |
NMO:
-autoimmune, but IgG against aquaporin 4
-hits optic nerves and spinal cord more than the brain because those are areas enriched with aquaporin-4 |
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Which is worse, NMO or MS, and why? |
NMO tends to be worse; requires tougher treatments, such as plasmapheresis |
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What are three other "names" of ADEM? |
-postvaccinal EM
-postinfectious EM
-allergic EM |
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What is a very important diagnostic factor for ADEM in particular? |
a good patient history |
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What is the common pattern of ADEM? |
viral disease --> partial recovery --> ADEM |
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What patient populations does ADEM tend to affect and why? |
kids and young adults - immune systems that haven't quite "calmed down" yet |
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How fatal is ADEM? |
rarely - usually recover with minimal lasting deficits |
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What is the general cause of central pontine myelinolysis? |
several electrolyte or osmolar imbalance |
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What are 5 things that could cause the severe electrolyte or osmolar imbalance leading to central pontine myelinolysis? |
1) too rapid correction of hyponatremia
2) EtOH withdrawal
3) liver disease
4) malnutrition
5) severe burns |
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What are the range of outcomes for central pontine myelinolysis? |
1) reversible with no deficits -managed well, patient rides it out
2) locked-in syndrome -pons destroyed, patient can only blink and move eyes, cannot move anything else
3) death |
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What is the general basis of neural tube closure defects? |
-neural plate normally curls up into a tube
-closure happens in stages
-Pax3 gene mutation causes NTDs, with increased risk if mom's diet is deficient in folate |
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Which fetuses are more sensitive to NTDs? Male or female? |
females |
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What are the three big NTDs? |
1) spina bifida
2) rachischisis
3) anencephaly |
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Rate of occurrence for spina bifida? |
~18 per 100,000 births |
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What is the mildest form of spina bifida and how does it present? |
occulta - defect in vertebral arch |
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What is the "middle" form of spina bifida and how does it present? |
meningocele - protrusion of meninges |
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What is the most severe form of spina bifida and how does it present? |
myelomeningocele - protrusion of meninges and spinal cord |
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What is rachichisis and what causes it? |
-exposed spinal cord
-caudal neuropore doesn't close |
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Rachichisis often presents in conjunction with what other NTD? |
anencephaly |
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What is anencephaly and what causes it? |
-absence of brain, skull, and scalp
-rostral neural tube doesn't close |
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What is the occurrence of anencephaly? |
1 per 10,000 births |
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What is the general basis behind neuronal progenitor migration malformations? |
-progenitor cells arise in the periventricular germinal matrix
-they migrate up into the cortex using radial glial cells as a guide
-Cajal-Retzius cells prevent progenitors from going too far |
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What are the three main neuronal progenitor migration malformations? |
1) neuronal heterotopias
2) lissencephaly
3) polymicrogyria |
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What is a neuronal heterotopia? |
grey matter where it shouldn't exist |
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What is an "undershooting" neuronal heterotopia called? |
periventricular nodular heterotopia
start to become neurons in white matter |
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What is an "overshooting" neuronal heterotopia called? |
leptomeningeal glioneuronal heterotopia |
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What can neuronal heterotopias sometimes be associated with? |
-epilepsy
-low IQ
OR
-may be completely normal (depends on how many & locations) |
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What is lissencephaly? |
"smooth brain" - not enough neurons reach the cortex |
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What is the severest form of lissencephaly? |
agyria |
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What is the less severe form of lissencephaly? |
pachygyria |
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What is polymicrogyria and what is the result? |
-a disruption in the latter stages of neuronal migration and cortical layering
-too many gyri, too small |
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Is polymicrogyria limited to one location? |
no; can be regional or widespread |
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What is holoprosencephaly? |
failure of forebrain vesicle to split into 2 hemispheres
*(think about cyclopia pics) |
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What is a common molecular defect underlying holoprosencephaly? |
defects in sonic hedgehog pathway |
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What are the three variants of holoprosencephaly? |
1) alobar - worst
2) semilobar
2) lobar - may be nearly normal |
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Why should pregnant women not take statin drugs? |
-mess with cholesterol -cholesterol very important for cell-to-cell and cell-to-ECM signaling -sonic hedgehog pathway very dependent on it -disruption could lead to holoprosencephaly |
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What are 3 possible causes of holoprosencephaly? |
1) maternal diabetes
2) fetal alcohol syndrome
3) trisomies 13 & 18 |
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What is the incidence of holoprosencephaly? |
<1 per 10,000 |
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What is the incidence of Dandy-Walker? |
1 per 30,000 births |
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What are the three components of Dandy-Walker? |
1) absence of cerebellar vermis
2) dilated fourth ventricle
3) enlarged posterior fossa |
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What causes Dandy-Walker? |
hindbrain development arrest |
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What is often seen in conjunction with Dandy-Walker? |
hydrocephalus, other neurologic problems |
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What is a Chiari malformation? |
cerebellar herniation through the foramen magnum |
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What is a Type I Chiari malformation and how does it present? |
-herniation of tonsil
-most of the time asymptomatic
-may present with ataxia, hydrocephalus, SIDS |
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What is a Type II Chiari malformation? |
-herniation of vermis plus brainstem displacement
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What is often associated with Type II Chiari malformation? |
lumbosacral myelomeningocele |
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80% of those with Type II Chiari malformation also have... |
hydrocephalus |
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What is a Type III Chiari malformation? |
cerebello-encephalocele |
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What are you guaranteed to have with a Type III Chiari malformation? |
other abnormalities |