6 - MS and Inflammation Flashcards
what is the composition of the myelin sheath?
- lipids - galactocerebroside
- glycoproteins - MBP, MOG, MAG
what are the glycoproteins:
* MBP?
* MOG?
* MAG?
MBP - myelin basic protein
MOG - myelin oligodendrocyte glycoprotein
MAG - myelin associated glycoprotein
what is found between the sections of myelin sheath on neurons?
nodes of Ranvier
what is saltatory conduction?
electrical impulse jumps from node to node along axon, speeding up the arrival time of the impulse at the nerve terminal
voltage gated Na+ channels are only present at what point of the neuron?
nodes of Ranvier
describe the conduction of an unmyelinated axon vs a myelinated axon:
unmyelinated - 0.5-10m/s
myelinated - 150 m/s
what is MS?
- slow progressive CNS diease characterised by teh destruction of the myelin sheath around the axons in the brain and spinal cord
- immune cells attack against oligodendrocytes = several neurological symptoms
how does a demyelinated axon affect conduction?
- alters saltatory conduction
- slower conduction
does MS pathology occur in grey or white matter?
can occur in both
what findings can be present on MRI that may indicate MS?
- lesions - white plaques
- loss of cortical volume
- shrinking of gyrus
new lesions do not always result in symptoms!!!
what is benign MS?
- very short episodes of mild neurological symptoms
- return to normal between attacks
- do not worsen during subsequent attacks
after 20 years, roughly what % of MS pts will develop SPMS?
50% of those with initial relapsing-remitting
how is disability most commonly measured?
expanded disease severity scale (EDSS)
what is the typical age of onset of MS?
20-40
where is the world is MS prevalence higher?
areas far from the equator - vit D deficiency
what do twin studies show about the inheritance of MS?
- MZ - 25% chance of both developing if one does
- DZ - 3% chance of both developing if one does
what chromosome may have some association with MS?
chromosome 6 - contains MHC class gene and myelin proteins
what environmental factors have been associated with MS?
- viruses
- bacterial infections
- nutritional and dietary factors
- Vit D
what viruses have been implicated in MS?
Hep B
epstein barr
what is the blood brain barrier?
membrane that controls the passage of substances from the blood into the CNS
normally, the BBB makes the CNS inaccessible to what?
T lymphocytes
white lesions on MRI indicate what?
areas of inflammation and open blood-brain barrier
when is CSF analysis particularly useful?
PPMS - where there are few lesions
what is a typical VEP for MS pts?
delayed and reduced
what is a common cause of delayed VEP in MS pts?
optic neuritis - shows as brightening around optic nerve on MRI
