Multiple Sclerosis Flashcards
what is the hypothesized etiology of MS
autoimmune condition induced by viral or other infectious agent (ie herpes, measles, epstein-barr, chlamydial pneumonia)
- may be a genetic susceptibility to immune system dysfunction
what is the pathophys of MS
- immune system triggers production of T-lymphocytes, macrophages, immunoglobulins
- failure of BBB, allows immune cells to cross and attack myelin sheath
- demyelination accompanied by local inflammation
- gliosis (proliferation of neuroglial tissue) occurs and results in “glial scars” or plaques
- axon becomes damaged, undergoes degen
- axonal loss occurs and interferes w normal conduction of nerve signals & loss of function
what about the pathophys of MS leads to a poorer prognosis
less capability for repair w attack in CNS bc of scarring
peak age onset
30yo
- between 15 and 50yo
what populations at higher and lower risk for MS and what does this indicate
more common in caucasian
more common in women
lower risk in AA, asian, and NA
implies a genetic link bc of racial disparity
why is MS difficult to get a clear definitive dx
d/t variability in periods of flares/remission and in clinical courses
what are methods to medically dx MS
CSF markers
- oligoclonal bands (presence of IgG bands)
MRI changes (w gadolinium contrast)
visual evoked potentials
why are MRIs tricky to use as a diagnostic tool in MS
even tho we know glial plaques are forming anywhere in CNS -> this is very spotty and often not visible early on
gadolinium contrast will inc specificity/sensitivity
why/how is visual evoked potentials used to dx MS
measures time nerve impulse takes to travel from retina to visual cortex
bc optic nerve so long and runs thru entire brain -> common area for plaques to form
- visual disturbances are a common sx
what is the struggle w differential dx
no single, definitive test
plaques can form anywhere, hard to implicate one neuro condition
differential dx list is extensive, and remissions make dx challenging
what is the Poser criteria and what is its purpose
presence of 2 episodes over time and evidence of 2 or more lesions in separate regions of CNS
created to inc speed of dx MS
what are 4 categories of differential dx to consider
autoimmune/inflammatory conditions
CNS infections
metabolic conditions
vascular conditions
what are 6 common sites of MS plaque formation
- periventricular regions of cerebrum
- grey/white matter boundary in cerebrum
- cerebellar white matter
- brainstem
- spinal cord (cervical)
- optic nerve
why is it difficult to give an accurate prognosis for MS
many factors involved and variability
how is variability seen in MS
plaques can be anywhere in CNS therefore any and all neuro s/sx are possible
progression of dz is also highly variable and hard to predict
what can rate of progression of MS be related to
intrinsic factors
- dz expression
extrinsic factors
- lifestyle
- weather
- meds
- exercise
what is an MS exacerbation, relapse, or flare?
new or recurrent sx that lasts more than 24hrs
must be separated from previous flare by at least 30days
what is the most common trigger for both MS pseudoexacerbation and prolonged exacerbations
heat intolerance
what is a pseudoexacerbation
new/recurrent sx that lasts less than 24hrs
what are common triggers for MS exacerbations
stress
infections
excessive fatigue
trauma, surgery
childbirth
decline in health status, infection, fever
heat - fever, exercise, hot bath/shower, hot weather conditions
what are the 4 clinical subtypes of MS
- relapsing-remitting (RRMS)
- primary-progressive (PPMS)
- secondary-progressive (SPMS)
- progressive-relapsing (PRMS)
what is RRMS
defined by acute attacks w full recovery or partial residual deficit
- there is a lack of dz progression in between attacks
what clinical subtype are most people w MS initially dx with and what is the difficulty w this
RRMS
- makes it difficult to dx, while it is good bc of periods of remission
what are the most common first signs of RRMS
optic neuritis (40%)
severe/acute vertigo (48%)