6 - MS and Inflammation

Question 1

what is the composition of the myelin sheath?

Answer 1

• lipids - galactocerebroside
• glycoproteins - MBP, MOG, MAG

Question 2

what are the glycoproteins:
* MBP?
* MOG?
* MAG?

Answer 2

MBP - myelin basic protein
MOG - myelin oligodendrocyte glycoprotein
MAG - myelin associated glycoprotein

Question 3

what is found between the sections of myelin sheath on neurons?

Answer 3

nodes of Ranvier

Question 4

what is saltatory conduction?

Answer 4

electrical impulse jumps from node to node along axon, speeding up the arrival time of the impulse at the nerve terminal

Question 5

voltage gated Na+ channels are only present at what point of the neuron?

Answer 5

nodes of Ranvier

Question 6

describe the conduction of an unmyelinated axon vs a myelinated axon:

Answer 6

unmyelinated - 0.5-10m/s
myelinated - 150 m/s

Question 7

what is MS?

Answer 7

• 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

Question 8

how does a demyelinated axon affect conduction?

Answer 8

• alters saltatory conduction
• slower conduction

Question 9

does MS pathology occur in grey or white matter?

Answer 9

can occur in both

Question 10

what findings can be present on MRI that may indicate MS?

Answer 10

• lesions - white plaques
• loss of cortical volume
• shrinking of gyrus

new lesions do not always result in symptoms!!!

Question 11

what is benign MS?

Answer 11

• very short episodes of mild neurological symptoms
• return to normal between attacks
• do not worsen during subsequent attacks

Question 12

after 20 years, roughly what % of MS pts will develop SPMS?

Answer 12

50% of those with initial relapsing-remitting

Question 13

how is disability most commonly measured?

Answer 13

expanded disease severity scale (EDSS)

Question 14

what is the typical age of onset of MS?

Answer 14

20-40

Question 15

where is the world is MS prevalence higher?

Answer 15

areas far from the equator - vit D deficiency

Question 16

what do twin studies show about the inheritance of MS?

Answer 16

• MZ - 25% chance of both developing if one does
• DZ - 3% chance of both developing if one does

Question 17

what chromosome may have some association with MS?

Answer 17

chromosome 6 - contains MHC class gene and myelin proteins

Question 18

what environmental factors have been associated with MS?

Answer 18

• viruses
• bacterial infections
• nutritional and dietary factors
• Vit D

Question 19

what viruses have been implicated in MS?

Answer 19

Hep B
epstein barr

Question 20

what is the blood brain barrier?

Answer 20

membrane that controls the passage of substances from the blood into the CNS

Question 21

normally, the BBB makes the CNS inaccessible to what?

Answer 21

T lymphocytes

Question 22

white lesions on MRI indicate what?

Answer 22

areas of inflammation and open blood-brain barrier

Question 23

when is CSF analysis particularly useful?

Answer 23

PPMS - where there are few lesions

Question 24

what is a typical VEP for MS pts?

Answer 24

delayed and reduced

Question 25

what is a common cause of delayed VEP in MS pts?

Answer 25

optic neuritis - shows as brightening around optic nerve on MRI