Multiple Sclerosis

Question 1

Which cells are myelin producing cells?

Answer 1

CNS: Oligodendrocytes
PNS: Schwann cells

COPS

Question 2

MS is the CNS analog of what disease?

Answer 2

Guillain-barre

Question 3

What kinds of stimulations lead to the creation of memories?

Answer 3

1. Visual
2. Tactile
3. Auditory
4. Interoceptive

Question 4

What types of countries have higher incidence with MS?

Answer 4

The more northern countries (Canada, US, Norway)

Question 5

Why is incidence of MS in Africa lower?

Answer 5

Challenge the immune system early in countries with poor sanitation, so better prepared for these disorders later in life.

Question 6

How long do symptoms last in a typical relapse?

Answer 6

2-3 wks

Question 7

Do patients ever return to baseline disability during diagnosis period?

Answer 7

No

Question 8

What are some of the factors that may be triggers for MS?

Answer 8

Infectious agents (if your body thinks it’s epstein-barr),
genetic predisposition,
environmental factors —> lead to abnormal immunologic response –> MS

Question 9

What role does myelin play in propagating the AP?

Answer 9

Myelin increases resistance and capacitance of cell membranes –> increased conduction speed.

Question 10

What causes demyelination and axonal loss in MS?

Answer 10

1. T-cells are called to the brain because they think that something like Epstein-Barr is there.
2. T-cells cross the BBB and become trapped in the brain.
3. The T-cells recognize myelin as an antigen, and cause a cascade of events to inflame, demyelinate and degrade axons

Question 11

Dawson’s Fingers

Answer 11

Demyelination plaques around the veins at the lateral ventricles in patients with MS

Question 12

The Open Ring Sign

Answer 12

Lesions take contrast, but contrast should not normally get through BBB —> Shows active BBB disruption

Question 13

Diffuser tensor imaging

Answer 13

A method to visualize the tracks of the brain

Question 14

Does a MS patient use more or less neurons to do a simple task?

Answer 14

More - compensate for loss of function/slow pathway

Question 15

What are the consequences of demyelination in nerve conduction?

Answer 15

Inefficiency to propagate signals to the rest of the body.

1. Longer conduction periods
2. Decreased amplitudes of AP
3. Total conduction block of AP

Question 16

If you have demyelination and you go for a visual response, how will be the latency of the response? Short or long? <– He asked this like 4 times in class

Answer 16

Prolonged

Question 17

What drugs alleviate the symptoms of MS?

Answer 17

1. Na Channel blockers (Phenytoin and Flecainide)
2. Dalfampridine

These do not change the disease state, they are just for they symptoms.

Question 18

What happens if you have increased Na entry into the cell?

Answer 18

1. Na builds up in the cells, and Na/K pump cannot efficiently remove the excess.
2. As it builds up, Ca/Na exchanger reverses the direction and Ca enters the cell.
3. Ca buildup leads to degeneraion

Question 19

How do Na channel blockades work?

Answer 19

Block some of the Na channels that are exposed as a result of demyelination

This works because normally myelin insulates these channels to prevent the excess Na entry (which leads to slow nerve conduction).

Question 20

How does Dalfampridine work?

Answer 20

Blocks K+ channels in neurons, which leads to a prolonged AP and increased conduction.

Shown to increase walking speed by 25% as opposed to 5% in placebo group.

Question 21

a typical action potential begins where?

Answer 21

the axon hillock if sufficient depolarization takes place. (increasing Vm)

Question 22

what is the leading cause of disability in young women?

Answer 22

Multiple sclerosis

Question 23

What are common MS symptoms?

Answer 23

lesions in CNS resulting in:
fatigue
walking impairment
spasticity
cognitive impairment
bladder dysfunction
pain
mood instability
sexual dysfunction

(pretty much anything the brain controls)

Question 24

Name 2 Na channel blockers

Answer 24

phenytoin
flecainide

-meant to preserve axons