Demyelinating Disorders - Krafts Flashcards
What are the two most important traits of MS?
- Characterized by distinct episodes of neurological deficits (separated in time)
- Due to white matter lesions (separated in space) - can happen anywhere in brain but around the ventricles is common
What is MS?
- Most common demyelinating disorder
- Onset usually before 50 (typically diagnosed in 30s, younger person)
- Females >Males, 2:1
- Autoimmune demyelinating disorder
- You get episodes in MS- many different symptoms com and go - after while the patient gets a pattern which the dr can use to determine disease severity
What is the pathogenesis of MS?
- Immune system attacking myelin sheath
- Genetic + environmental factor causes
- Linked to HLA-DR2 (3X more likely to get MS); also linked to some IL-2 and IL-7 receptor polymorphisms (many variants)
- Disease probably caused by T cells that react against myeline antigens and secrete cytokines that recruit macrophages to eat myelin
- B cells probably play a role (with depleted B cells, you don’t get as many plaques)
What do oligoclonal bands look like in MS?
They are present at the bottom of the band in CSF of MS (and always in blood - even normal)
-The bands indicate a whole bunch of a certain type of antibody is present
Where are plaques usually located? What is there prevalence in the brain?
Adjacent to ventricles & LOTS of them
What do plaques feel like?
Often firmer than surrounding brain
What are the characteristics of active plaques?
- Lipid-stuffed macrophages (chewing up the myelin)
- T cells cuffing vessels
- Axons preserved
What are characteristics of inactive plaques?
- No myelin
- Dec. oligodendrocytes
- Gliosis (astrocytes coming in to proliferate and repair after damage - reestablishing neuropil & BBB)
- Most cells around = astrocytes
- Decreased axon number
What type of matter are plaques in?
White matter, maybe at junction of white and gray matter or near ventricles (but could possibly occur anywhere)
What are hyper intense regions on MRI?
Active plaques!
What are central nervous system clinical features of MS?
- UNILATERAL VISUAL IMPAIRMENT (frequent initial manifestation of disease) –> optic nerve involvement
- Cranial nerve signs, ataxia, nystagmus (brainstem involvement)
What are spinal manifestations/clinical features of MS?
- Motor/sensory impairment of trunk and limbs
- Spasticity
- Problems with voluntary bladder control
What do plaques look like in comparison to white matter?
Sunken in, darker than white matter, more firm
What do plaques often follow?
Blood vessels!!
What does an MS plaque around a blood vessel look like?
- Oligodendrocytes on outside, lymphocytes on inside
- Cuffing of lymphocytes hanging out around vessels
What does MS look like in myelin stain?
Myelin stains deep bluish purple & plaque is lighter pink color.
What is this description?
- Diffuse, monophasic, demyelination following viral infection; usually in children
- Rapid onset headache, lethargy, coma
- Fatal in 10%; rest recover completely
- May be an acute autoimmune reaction against myelin
ADEM -Acute Disseminated Encephalomyelitis
When do quick onset demyelinating disorders usually occur?
After viral infection or vaccination in kids - within a week or 2, suddenly have symptoms that are nonspecific - headache, lethargic, can lapse into a coma
What is this description?
- Fulminant (severe, sudden) CNS demyelination
- Young adults, children
- Preceded by URI
- Fatal in many patients; significant deficits in survivors
- May be hyper acute variant of ADEM
Acute Necrotizing Hemorrhagic Encephalitis
What is this description?
- Symmetric loss of myelin in basis pontis and part of pontine tegmentum
- Rapid correction of hyponatremia
- Rapidly evolving quadriplegia
- Monophasic disease (so all lesions are at the same stage of myelin loss) - lesions don’t come and go
- Usually happens after you do something to the patient
- Common in malnutrition, alcoholism, liver transplant, or too little salt (hyponatremia) in blood and you correct it –> then it causes this condition
- If you correct the osmotic gradient in body too fast, you cause this condition
- Starts as flaccid paralysis or other paralysis and then patient may die or get better
Central Pontine Myelinolysis
