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71 Cards in this Set

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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)

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


What can repeated bouts of MS cause?

axon breakage which may not heal

In what group of people is MS more common?

-white (over black) females (over males)



-both 2:1 ratios

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

What are the radiological findings of MS?

multiple white matter lesions that change over time (have to see a series of images)

How may you diagnosis MS?

-mostly a diagnosis of exclusion; see multiple lesions in time and space



-oligoclonal bands in CSF

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

What is the differential diagnosis for MS?

1) cerebrovascular disease



2) other autoimmune demyelinating diseases



3) viral encephalitis



4) neoplasms

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

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%


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

What are the two big categories of therapy for MS?

1) maintenance/prevention



2) relapses

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)

What are the medicines for dealing with relapses of MS?

1) oral prednisone



2) IV methylprednisolone

Why and how do we hit relapses of MS so aggressively?

steriods - trying to prevent axonal breakage

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

What is tumefactive MS?

a severe attack of MS that one would think is probably brain cancer - resembles a glioblastoma radiologically and histologically

How can we distinguish tumefactive MS from a glioblastoma?

molecular diagnostics

What is the other name for neuromyelitis optica?

Devic's disease

What other disease does NMO very closely resemble?

MS

What is the difference in NMO and MS demographically?

NMO affects blacks > whites

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

Which is worse, NMO or MS, and why?

NMO tends to be worse; requires tougher treatments, such as plasmapheresis

What are three other "names" of ADEM?

-postvaccinal EM



-postinfectious EM



-allergic EM

What is a very important diagnostic factor for ADEM in particular?

a good patient history

What is the common pattern of ADEM?

viral disease --> partial recovery --> ADEM

What patient populations does ADEM tend to affect and why?

kids and young adults - immune systems that haven't quite "calmed down" yet

How fatal is ADEM?

rarely - usually recover with minimal lasting deficits

What is the general cause of central pontine myelinolysis?

several electrolyte or osmolar imbalance

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

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

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

Which fetuses are more sensitive to NTDs?


Male or female?

females

What are the three big NTDs?

1) spina bifida



2) rachischisis



3) anencephaly

Rate of occurrence for spina bifida?

~18 per 100,000 births

What is the mildest form of spina bifida and how does it present?

occulta - defect in vertebral arch

What is the "middle" form of spina bifida and how does it present?

meningocele - protrusion of meninges

What is the most severe form of spina bifida and how does it present?

myelomeningocele -


protrusion of meninges and spinal cord

What is rachichisis and what causes it?

-exposed spinal cord



-caudal neuropore doesn't close

Rachichisis often presents in conjunction with what other NTD?

anencephaly

What is anencephaly and what causes it?

-absence of brain, skull, and scalp



-rostral neural tube doesn't close

What is the occurrence of anencephaly?

1 per 10,000 births

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

What are the three main neuronal progenitor migration malformations?

1) neuronal heterotopias



2) lissencephaly



3) polymicrogyria

What is a neuronal heterotopia?

grey matter where it shouldn't exist

What is an "undershooting" neuronal heterotopia called?

periventricular nodular heterotopia



start to become neurons in white matter

What is an "overshooting" neuronal heterotopia called?

leptomeningeal glioneuronal heterotopia

What can neuronal heterotopias sometimes be associated with?

-epilepsy



-low IQ



OR



-may be completely normal


(depends on how many & locations)

What is lissencephaly?

"smooth brain" -


not enough neurons reach the cortex

What is the severest form of lissencephaly?

agyria

What is the less severe form of lissencephaly?

pachygyria

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

Is polymicrogyria limited to one location?

no; can be regional or widespread

What is holoprosencephaly?

failure of forebrain vesicle to split into 2 hemispheres



*(think about cyclopia pics)

What is a common molecular defect underlying holoprosencephaly?

defects in sonic hedgehog pathway

What are the three variants of holoprosencephaly?

1) alobar - worst



2) semilobar



2) lobar - may be nearly normal

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

What are 3 possible causes of holoprosencephaly?

1) maternal diabetes



2) fetal alcohol syndrome



3) trisomies 13 & 18

What is the incidence of holoprosencephaly?

<1 per 10,000

What is the incidence of Dandy-Walker?

1 per 30,000 births

What are the three components of Dandy-Walker?

1) absence of cerebellar vermis



2) dilated fourth ventricle



3) enlarged posterior fossa

What causes Dandy-Walker?

hindbrain development arrest

What is often seen in conjunction with Dandy-Walker?

hydrocephalus, other neurologic problems

What is a Chiari malformation?

cerebellar herniation through the foramen magnum

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

What is a Type II Chiari malformation?

-herniation of vermis plus


brainstem displacement


What is often associated with Type II Chiari malformation?

lumbosacral myelomeningocele

80% of those with Type II Chiari malformation also have...

hydrocephalus

What is a Type III Chiari malformation?

cerebello-encephalocele

What are you guaranteed to have with a Type III Chiari malformation?

other abnormalities