Demyelinating Disorders Flashcards
What is the most common demyelinating disorder?
MS
For MS: gender? onset?
female, usually before age 50
What is MS chracterized by?
distinct episodes of neurologic deficits separated in time due to white matter lesions separated in space
What is the general pathogenesis of MS?
immune attack on the myelin sheath
Probably caused by T-cells that autoreact against myelin antigens and secrete cytokines to turn macrophages on and eat them
B cells probably play a role too (since there are oligoclonal bands) but we don’t really know how
Is MS totally genetic?
NO - there is a genetic predisposition but there is some environmental factor as well
How is oligoclonal bands in the CSF diagnostic for MS?
Usually in the gamma region (where the antibodies divide out), there is just a smear through, because antibodies are normally monoclonal and ther eisn’t an abundance of any specific antibody - you want to be able to kill just about anythign that could possibly come into the system
However, in MS, you have oligoclonal bands in the gamma region when you run the CSF through.
What will you see on gross pathology in MS?
plaque formation - lots of them
How are active plaques different from inactive plaques?
active plaques have lipid-stuffed macrophages, T cells cuffing the vessels and axons still present
inactive plaques are when the deed is already done - no myelin left, decreased number of axons, astrocytic gliosis, and decreased oligodendrocytes
Where do plaques typically form?
they can be anywhere, but they are commonly located near the ventricles and around blood vessels
What will an MS plaque look like on histology?
- plaque will stain pale on an H&E stain
- there will be very few oligodendrocytes
- gliosis present
- lymphocytes cuffing the blood vessels
What is another stain you can use when looking at an MS plaque?
a myelin stain - it will stain myelin dark purple
What is an extremely common place for MS plaque to form - usually causing the precipitating symptom?
in the optic nerve near the chiasm
What are the two general types of active plaque patterns you see in MS?
Individual patients with MS tend to have either sharply demarcated plaques around blood vessels or poorly demarcated plaques not around blood vessels - they don’t have a combination of both
What are shadow plaques?
they are plaques where the border is indistinct because of thin myelin sheaths are the edges
remyelination? They’re trying to figure that out.
What are some of the central symptoms of MS?
unilateral visual impairment is usually the presenting concern
cranial nerve signs
ataxia
nystagmus
What are some of the spinal manifestations of MS?
motor/sensory iimpairment of trunk and limbs
spasticity
problems with voluntary bladder control
What is acute disseminated encephalomyelitis?
It’s diffuse, monophasic demyelination following a viral infection - usually in children
extremely rare
What are the symptosm of acute disseminated encephalomyelitis? Progrnosis?
rapid onset headache, lethargy, coma (so not very specific)
fatal in 10%, the other 90% has a complete recovery without subsequent deficit
What do they think is the mechanism behind acute disseminated encephalomyelitis?
they accume is a cross-reactivity of the immune system against he myelin after aa viral infection
What is acute necrotizing hemorrhagic encephalomyelitis?
It’s the bad one
You get fulminant CNS demyelination with necrosis and hemorrhage - often in yound adults or children after URI
What is the progrnosis with acute necrotizing hemorrhagic encephalomyelitis?
fatal in many patients and those that survive often have deficits
How do we cause central pontine myelinolysis?
By correcting hyponatremia too quickly
it’s a symmetric loss of myelin in the basis pontis and part of the pontine tegmentum
What are the symptoms of central pontine myelinolysis?
It usually happens in patients that are just really sick
you treat the hyponatremia, they start to feel much better for a couple days and then they get a rapidly evolving quadriplegia and coma
it’s a monophasic disease
