Demyelinating Diseases Flashcards

1
Q

Demyelinating Disorders

A

Disorders characterized by loss of myelin around the axons

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2
Q

Types of Myelin Disorders

A
  1. Loss of myelination (demyelination) - damage to normal myelin
    - Multiple sclerosis, Myelinolysis & Post-infectious/immune (ADEM, AHEM)
  2. Improper formation of myelin (Dysmyelination) - defective myelin synthesis or turnover
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3
Q

Multiple Sclerosis

A

Autoimmune demyelinating disorder w/ episodes of disease activity that produce white matter lesions

MC demyelinating disease
“Relapsing & Remitting” course

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4
Q

Epidemiology, Etiology & RFs of MS

A
F:M = 2:1 (Young adults- 20-30 years)
Unknown etiology
- Smoking
- Low Vit D (Farther away from equator)
- Race (white)
- EBV infection
- Genes- HLA-DR
Exacerbated by Inc body temp (hot baths, exercise)
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5
Q

Pathogenesis of MS

A

Autoimmune response directed against components of the myelin sheath
• Th1 and Th17 T cells react against myelin antigens and secrete cytokines –>
recruitment and activation of leucocytes –> demyelination

Both genetic and environmental factors are implicated

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6
Q

Gross morphology changes in MS

A
  • Multifocal white matter lesion

Plaques

  • Firmer than surrounding areas
  • Well-circumscribes, slightly depressed, glassy appearing, gray-tan lesions
  • Commonly adjacent to ventricles, in optic nerves, chiasm, brainstem, ascending & descending fiber tracts, etc.
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7
Q

Microscopic changes in MS

A

Active plaques

  • Abundant macrophages & ongoing myelin breakdown
  • Perivascular lymphocytic inflammation

Inactive plaques

  • Little/no myelin left
  • Prominent astrocytic proliferation & gliosis
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8
Q

CFs of MS

A
  • Acute optic neuritis - painful unilateral vision loss w/ Marcus Gunn pupil
  • Diplopia, ataxia, scanning speech, intention tremor, nystagmus/INO (b/l > u/l) (Brainstem / Cerebellar)
  • Weakness & spasticity (Pyramidal tract)
  • Electric-shock sensation, neurogenic bladder, paraparesis, sensory effects on truck & extremity - Spinal cord
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9
Q

Lab finding in MS

A

CSF

  • Inc proteins (MBP- Myelin Basic Protein)
  • Inc Immunoglobulins (IgG) (oligoclonal bands are diagnostic)
  • Moderate pleocytosis
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10
Q

MS Treatment

A

B-interferon, Glatiramer & Natalizumab
- Slow relapses & progression

IV steroids
- Acute flares

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11
Q

Post-Infectious Demyelination

A

Immune-mediated demyelination ff infections

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12
Q

Etiology & Pathogenesis of Post Infectious Demyelination

A
  • Viral infections or Vaccination

- Cross-reacting Ab –> Myelin damage

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13
Q

Patterns of Post- Infectious Demyelination

A
  1. Acute Disseminated Encephalomyelitis (ADEM)

2. Acute Hemorrhagic Encephalomyelitis (AHEM)

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14
Q

Acute Disseminated Encephalomyelitis (ADEM)

A
  • Rapid progression (1-2wks after infection)
  • Non-localizing symptoms (different from MS)
  • Most recover completely
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15
Q

Acute Hemorrhagic Encephalomyelitis (AHEM)

A
  • Mostly children & young adults

- Usually fatal (more devastating than ADEM)

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16
Q

Central Pontine Myelinolosis

A

Non-immune damage to oligodendrocytes in the pons

17
Q

Etiology of Central Pontine Myelinolysis

A

After rapid Hyponatremia correction

  • Renal or hepatic disease
  • Severe vomiting & diarrhea
  • CHF
  • SIADH
18
Q

CFS & Pathogenesis of Central Pontine Myelinolysis

A

Acute b/l paralysis

Unknown pathogenesis

19
Q

Thiamine Deficiency Encephalopathy

A

“Wernicke Encephalopathy”

- Abrupt onset

20
Q

RFs of Thiamine Deficiency

A
  • Chronic alcoholism

- Gastric disorders

21
Q

CFs of Thiamine deficiency

A

TRIAD of

  1. Encephalopathy & confusion
  2. Ocular palsies
  3. Ataxia
22
Q

Treatment of Thiamine deficiency

A
Thiamine administration (early)
- Delayed treatment can cause irreversible memory disturbances "Korsakoff's syndrome", no new memories & confabulations
23
Q

Pathological features of Thiamine Deficiency

A

Foci of hemorrhage & necrosis in mamillary bodies, thalamus & peri-aqueductal gray matter

24
Q

Neurological manifestation of Alcohol

A
  • Peripheral neuropathy
  • Cerebellar degeneration
  • Seizures (withdrawal syndrome)
  • Wernicke-Korsakoff syndrome - Thiamine deficiency
25
Q

Types of Glioma/ Glial cell tumors

A
  1. Astrocytes
    - Pilocytic astrocytoma
    - Glioblastoma
  2. Oligodendrocytes
  3. Ependymal cells
26
Q

Types of Astrocytoma

A
  1. Pilocytic astrocytoma (Grade 1)

2. Glioblastoma (Grade4 - Infiltrating)

27
Q

Pilocytic Astrocytoma

A
  • Childhood
  • Cerebellum
  • BRAF translocation
  • Cystic lesion w/ mural nodule
  • Bipolar cells w/ hairlike/pilo processes w. eosinophilic rod-like structures (Rosenthal fibers)
  • Glial Fibrillary Acidic Protein (GFAP) +ve on IHC
28
Q

Glioblastoma

A
  • Grade 4 metastatic tumor
  • Cerebrum
  • IDH wild or mutant (better prognosis)
  • Infiltrating tumor w/ hemorrhage & necrosis
  • Crossed the midline (Corpus callosum) “Butterfly glioma”
  • Microvascular proliferation w/ area of “Pseudo-palisading” necrosis
  • GFAP +ve on IHC
29
Q

Oligodendroglioma

A
  • Adults (40-50 years)
  • Cerebrum (frontal & temporal)
  • IDH mutation & 1p and 19q codeletion
  • Gray, cystic mass w/ focal hemorrhage & calcifications
  • Cells w/ round nuclei, clear cytoplasm forming halos & thin-walled capillaries “Fried egg appearance”
  • Insidious - years of antecedent neurological symptoms especially seizures
30
Q

Ependymoma

A
  • 0-20 years = 4th ventricle BUT Adults = Spinal cord
  • Ependymal cells lining ventricular cavity
  • NF2 gene on Chr22 (spine)
    Hydrocephalus & Spinal cord deficits
  • Round-oval nuclei & abundant granule chromatin; Variable fibrillary background
  • Rosettes w/ long processes extending into the lumen
  • “Perivascular Pseudo-rosettes” - surrounding vessels
31
Q

Embryonal tumors

A

Medulloblastoma

  • Neuroectodermal origin
  • Small round cells (remnants of normal progenitor cells during embryology)
32
Q

Medulloblastoma

A
  • MC CNS malignancy in children
  • Cerebellum (posterior fossa)
  • Wnt-B catenin pathway & MYC overexpression
  • Grade 4; Highly malignant –> Through CSF “Drop metastasis” to Cauda equina”
  • Tx = Radiosensitive but poor prognosis (better w/ B-catenin involvement)
  • Well-circumscribes, gray, friable (May involve Leptomeninges)
  • Sheets of small round blue anaplastic cells w/ hyperchromatic nuclei, abundant mitosis & scant cytoplasm
    “Homer Wright Rosettes” in Classic type
33
Q

Meningioma

A
  • Arachnoid meningothelial cell (attached to dura)
  • Adults
  • External surface of brain or Ventricular system
  • Chr 22q
  • Prognosis depends on size, location, surgical accessibility & histological grade
  • Whorled, tight clusters of cells w/o visible cell membrane + “Psammoma bodies”
    Associated w/ NFA - Multiple meningioma + 8th nerve Schwannoma or glial tumors
34
Q

Schwannoma

A
  • Benign encapsulated tumor that may occur in soft tissues, internal organs or spinal nerve roots
  • Vestibular branch of CN8 “Acoustic neuroma/ Vestibular schwannoma”
  • Chr 22q & NF2 association
  • Well-circumscribed mass loosely attached to nerve
  • Antoni A area (dense & pink), Antoni B area (loose & pale) & Hyalinized blood vessels
    “Verocay bodies” –> Nuclei of tumor cells in Antoni A area aligned in palisading rows
35
Q

Secondary CNS tumors

A

MC metastatic carcinomas from Lungs, breast, skin (melanoma), kidney & GIT

  • Sharply-demarcated masses @ grey-white matter junction
  • 25-50% of intracranial tumors