Neuro 65: Demyelinating disorders Flashcards
What does MS look like grossly?
-while examining a portion of the CNS you will see that a portion that is supposed to be white is pale gray or tan = myelin is missing
Leukodystrophies
-disorders characterized by improper synth, turnover, or maintenance of myelin
Progressive multifocal leukoencephalopathy
-infection that targets the oligodendroglia
Mjr pathophysiology of MS
- destruction of myelin and oligos by idiopathic, presumed autoimmune demyelination
- inflammatory demyelination/axonal conduction failure
- axonal loss
- atrophy
When is the onset of MS usually? & who is more commonly affected M or F?
- in young adults
- age 20-40
- much more common in women (2:1)
What is the basic course of MS?
- chronic, episodic disease
- usually begins with relapsing-remitting “stuttering” course –> then followed by a more progressive cumulative disability (usually after 10 yrs)
- lesions and sx are separated by time and space
- there is usually radiologic evidence of several lesions present by the time of the first sxs
Sx of MS
- sx are variable, they depend on the anatomic sites of the lesions
- the most common sx involve the visual system and the long tracts of the spinal cord
- small plaques in the spinal cord can have a significant clinical impact, while lgr plaques in the cortex may have less if they are not in an area related to a specific fctn
What the 3 mjr impacts MS has on pts?
- sustained and progressive physical disability
- cognitive dysfunction
- relapses
What is the epidemiology of MS?
- its the most common demyelinating disease
- more common in temperate zones
- seems to matter more where you grew up rather than where you end up as an adult to determine your risks for developing MS
- may have to do with an infection that people in temperate zones are more susceptible to
Dx of MS
- made usually after the SECOND attack
- use clinical s/sx and MRI
6 Features of the plaques in MS?
- in the white matter predominatly
- tend to follow the course of small veins
- can be in the grey matter too
- sharply demarcaited
- variable in size
- do not spare the subcortical U fibers
Loss of axons in MS
- there is a relative sparing of axons in plaques
- loss does occur though and can proceed continuously even without attacks –> causes cumulative disability, cog impairment, and brain atrophy
MS triggered by an infection?
- possible
- the IgG seen in the CSF is similar to that seen in an immune response to an infection
- an agent has not be identified yet though
What are 4 things that are evidence that an immune mechanism has a role in MS?
- the serum and the CSF of MS pts cause in vitro demyelination
- antibodies to myelin and oligodendroglia are present
- an MS pt’s T cells react to myelin in vitro
- there is therapeutic effectiveness of interferon-beta and natalizumab
How is a plaque in MS formed?
- activated T cells and monocytes leave the blood vessels and accumulate in the brain tissue
- these cells can damage the tissue directly or indirectly by secreting pro-inflam cytokines
- microglia and macs damage and phagocytize tissue in a developing MS plaque
