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Week 2 (Neuro 2) > Myelin Disorders > Flashcards

Myelin Disorders Flashcards

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1
Q

what are the three types of myelin disorders & how are they dfefined?

A
  • hypomyelinating: arrest in myelin production
  • dysmyelination: abnormal myelin production
  • demyelinating: desctruction of existing myelin
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2
Q

what is the key role of myelin?

A
  • faciliates electrical conduction by
    • increasing membrance resistance
    • decreasing membrane capacitance

(R and C inversely related)

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3
Q

myelin in the CNS

  • is what “kind”?
  • made by what cells?
  • contains which proteins?
A
  • compact myelin
  • made by: oligodendrocytes
  • contains:
    • PLP (proteolipid protein)
    • MBP (myelin basic protein)
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4
Q

myelin in the PNS

  • is what “kind” of myelin
  • made by what cells
  • includes what proteins
A
  • compact myelin
  • made by: schwann cells
  • contains
    • MPZ (myelin protein zero)
    • PMP-22 (peripheral myelin protein-22)
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5
Q

which myelin disorders are dysmyelinating diseases?

what does this mean?

A

= abnormal myelin production

  • frontal leukodystrophies
    • Alexander’s Disease
    • metachromatic leukodystrophy
  • posterior leukodystrophys
    • Krabbe’s disease
    • Adrenoleukodystrophy
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6
Q

alexander’s disease

  • what kind of myelination disorder?
  • cause?
  • presentation?
A
  • dysmeylination disorder - frontal leukodystrophy
  • cause: GFAP mutation leading to rosenthal fiber accumulation
  • presentation: infant with megalencephaly (enlarged brain)
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7
Q

metachromatic leukodystrophy

  • what kind of myelination disorder
  • cause
  • presentation
A
  • dysmyelination disorder - frontal leukodystrophy
  • causse: arysulftase A deficiency leading to cerebroside sulfate accumulation, impairing both
    • ​CNS myelination
    • PNS myelination
  • presentation:
    • juveline onset: development regression + seizures
    • adult onset: dementia + peripheral neuropathy + cholecystitis
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8
Q

krabbe’s disease

  • what kind of myelination disorder?
  • cause
  • presentation
A
  • dysmyelination disease
  • cause: galactocerebroside B-galactosidase deficiency
  • presentation: a lot goes wrong
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9
Q

adrenoleukodystrophy

  • what kind of myeliantion disorder
  • cause
  • presentation
A
  • dysmyelination disease - posteiror leukodystrophy
  • cause: adrenal neuropathy -> high plasma VLCFAS
  • presentation: adrenal insufficiency, +
    • childhood onset: behavior issues
    • adult onset: spasticity
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10
Q

which type of dysmyelination disorders leads to infants with megalencephaly?

A

Alexander’s Disease

(frontal leukodystrophy)

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11
Q

which dysmyelination disease involves cerebroside sulfate accumulation?

A

metachromatic leukodystrophy

frontal leukodystrophy

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12
Q

which dysmyelination disorder can be diagnosed with high plasma VLCFAs?

A

adrenoluekodystrophy

posterior leukodystrophy

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13
Q

list the mutation associated with each dysmyelination disease

A
  • Alexanders: GFAP
  • Metachromatic leukodstrophy: arylsulfatase A
  • Krabbe: galacterocerbrosidase B-galactosidase
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14
Q

multiple sclerosis - pathogenesis

A

autoreactive lymphocytes

  • ​​inflammatory response of Th-1, Th-17 & B-cells, causing
  • myelin dstruction + axonal destruction of the
  • gray + white matter
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15
Q

what are the major risk factors for MS?

A
  • Epstein Barr Virtus
  • Vit-D deficiency / low sunlight
  • smoking
  • adolescent obesity
  • high amplitudes
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16
Q

explain the role of amplitude in pre-disposition to MS

A
  • geographic affect on MS risk depends on age of moving
    • moving before 15 yo: adopt risks of new location (high or low altitude)
    • moving after 15 yo: adopt risks of initial location (high or low altidude)

high altitude = higher MS risk

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17
Q

what are the three categorizations of MS based on dissemination in time?

A
  • relapsing remitting (m/c): initial episode -> followed by relapses & remission
  • secondary progressive: initial episode -> remission -> gradual worsening
  • primary progressive: no initial episode -> gradual worsening
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18
Q

what is a clinically isolated syndrome (CIS)?

what are the clinical actively syndromes seen in MS?

A

definition: a solitary demylinating event lasting at least 24 hours

  • optic neuritis
  • brainstem
  • cerebellar
  • transverse myelitis
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19
Q

what is a radiologicaly isolated syndrome (RIS)?

A

an abnormal MRI in the absence of clinical symptoms

tends to preceed CIS

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20
Q

what are the common ocular manifesations of MS?

A
  • optic neuritis
  • optic atrophy (following optic neuritis)
  • internuclear opahtlmoplegia
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21
Q

optic neuritis in MS

  • demographics affected
  • clinical presentation
  • findings on work-up
A
  • demographic: F, 30s-40s
  • clinical presentation:
    1. rapid monocular vision loss of
      • depth perception
      • color saturation
    2. pain on extraocular movement
  • work-up:
    • PE:
      • significant edema
      • normal fundus
      • nosplinter hemorrhages
    • MRI: < 50% enhancement of optic nerve length
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22
Q

describe the type of vision loss caused by optic neuritis in MS

A
  • rapid onset
  • monocular
  • decreasing perception of:
    • depth
    • saturation
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23
Q

what two key ocular manifestations are NOT seen in optic neuritis?

Study These Flashcards
A
  • an abnormal fundus
  • splinter hemorrhages
24
Q

identify

Study These Flashcards
A

optic atrophy

MS

25
internuclear opathalmolplegia in MS * presentation * mechanism
* presentation: **inability to adduct the eye (unilateral or bilateral)** * cause: **injury to MLF** * ​carries fibers to oculomotor nucleus (CNIII), which * innervates the ipsilateral medial rectus, which * adducts ipsilateral eye
26
list the risk of MS development based on clinical findings
* low risk: CIS + normal brain MRI * medium risk: RIS w/ either spinal cord lesions OR oligoclonal bands * high risk: either * CIS + abnormal MRI (2+ lesions) * smokers * low Vit-D levels * \< 30 yrs old * very high risk: **CIS + abnormal MRI involving new disease activity**
27
pts with at _what risk_ for developing MS are treated?
high risk and very high risk (high risk tx with _disease modifying_ therapy)
28
which factors are associated with an _aggresive presentation_ of MS?
* **male, AA, onset \> 40 years** * + risk factors for eveloping MS: * obesity * smoking * Vit D
29
what set of criteria must be met to _make a diagnosis_ of MS?
McDonald Criteria * dissemination in time: more than one attack * dissemination in space: a lesion that * **is at least 3mm in the long axis** * at least 2 of the following areas: * cortical * juxtacortical * paraventircal * spinal cord: hemicord transverse myelitis
30
describes the lesions (plaques) that characterize multiple sclerosis
* \> 3mm lesions * cortical / juxtacortical - **ovoid** * paraventricular - **perpendicular, flame shaped** * tranverse myelitis (spinal) * **involves only _one_ vertebral segment** * **_hemicord_ & _NOT_ in central canal**
31
MS treatment what are the roles of DMTs (disease modifying treatments)?
* NOT for symptom improvement * serve to delay progression from CIS to MS
32
MS treatment what is the management for patients who refuse DMTs?
annual MRIs for 5 years
33
MS treatment which DMTs increase PML risk?
* **natalizumab** * fingolimod * rituximab * ocreliazumab * dimethyl fumarate DO follow no rules
34
MS treatment when shoud switching therapies be considered?
* 1 or more relapses * 1 year of worsening diasability * 2 or more new MRI lesions
35
MS treatment which MS patients should NOT be treated?
* CIS with normal MRIs [low risk] * CIS/MIS with NEDA [no evidence of disease activity] while _off therapy_ for 2 years
36
MS treatment treatment for **acute flares**?
methylprednisone
37
progressive multifocal leukoencephlopathy (PML) * definition * cause * demographics * MRI * treatment:
* definition: **potentially fatal demyelination** * cause: **JC virus reactivation** * demographics**: I/C -** HIV, transplants, chemo, natalizumab * MRI: gray white junction lesions that dont follow vascular territories * treatment**:** * PML: **plasma exchange** (qod x 5) * PML IRIS: **high dose steroids (**IVMP 1g/day x 5)
38
identify
MS lesions flame like, perpendicular to ventricles
39
identify
MS lesions cortical - ovoid shaped
40
identify
PML-IRIS
41
neuromyelitis optica (NMO) * cause * presentation * MRI
* cause: **antibodies to aquaporin-4, a water channel on astrocyte foot processes** * presentation: * **binocular optic neuritis** (with \> 50% optic nerve enhancement) * **area-postrema syndrome:** hiccups & N&V * MRI: **large lesions that follow ependymal lines** * brain - including diencephalon * spinal cord - LETM (longidutinally extensive transverse myelitis) * affects at least 3 segments * +/- complete, including central canal * may involve medulla
42
identify
neuromyeltis optica (NMO) lesions in diencephalon
43
identify
neuromyelitis optica (NMO) advancing LEMN coinciding with vomitting (area postrema) syndrome
44
identify
neuromyelitis optica (NMO) lesions that that are large (here - tumefactive lesions, which are \> 2cm) and don't obey ependymal lines
45
contrast the ocular presentations of * MS * NMO
* MS * monocular * optic nerve enhancement \< 50% * NMO * binocular * optic nerve enhancement \> 50%
46
contrast the lesions seen in * MS * NMO
* MS * brain: does not follow ependyma - ovoid, flame shaped * spinal cord (transverse myelitis) * hemicord * not including central canal * one vertebral segment * NMO * brain: follows ependyma, often includes diencehpalon, can be large * spinal cord: (LETM) * possibly complete * includes central canal * multiple vertebral levels -:\> possibly up to medulla
47
compare & contrast NMO based on * general prevalence * age of onset * co-existing autoimmunity * nature of optic neuritis * nature of myelitis * presence of diencephalon syndrome * presence of dawson's fingers * presence of tumefactive lesions * CSF features
48
area postrema syndrome * presents how? * is part of which syndrome? why?
* presentation: **hiccups, nausea & vomitting** * NMO: d/t LETM, which can affect the _medulla_
49
MOG antibody disease * cause * age of onset * presentation * MRI
* cause: **myelin oligodendrocyte glycoprotein antibody disease** * age of onset: 25 * presentation: binocular optic neurtiis + significant optic disc edema * MRI: * brain: involve gray matter * spinal cord (transverse mylitis) * LETM (affects multiple vertebral levels) * has a predilection for the _conus medullaris_ * involves central canal - _including gray matter_ * RARELY RECURRENT.
50
ADEM
* cause: triggered by inflammation - _often viral infection_ * age of onset: **children m/c (age 5-8 yo)** * presentation: **demylination + ENCEPHALOPATHY** * MRI: * ​brain: **involve gray matter (_basal ganglia_)** * spinal cord (myelitis): rarely seen
51
how does _tranverse myelitis_ * present clinically? * appear on MRI in each demylination disease?
* present: **flaccid paralysis with decreased reflexes** * lesions on MRI: * MS: single vertebral level, hemicord, no central canal * NMO: LETM that can include medulla, central canal involved * MOG: LETM w/ conus medullaris, central canal involved (up to gray matter), _rarely recurrent_ * ADEM: spinal cord involvement rare
52
which demylination disease can affect the _gray matter_ of the brain? explain
* ADEM (**basal ganglia involvement)** * MOG antibody disease
53
which demylenation disease _commonly presents_ with **optic disc edema**?
**MOG antibody disease** can occur in MS, but is insignificant
54
which demylination disease presents with spinal cord lesions that have a predilection for the conus medularis?
MOG antibody disease
55
which demylinating disease presents with LETM that typically does not recurr?
MOG antibody disease
56
list the m/c age group affected by each demylinating disease
* MS: 30-50, rarely \> 60 * NMO: \> 40, often \> 60 * ADEM: children m/c * MOG antibody disease: ~25

Week 2 (Neuro 2) (9 decks)

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