Neuro - Multiple Sclerosis

Question 1

What is MS?

Answer 1

Autoimmune disorder involving the demyelination of neurones in the CNS

Question 2

What are the symptoms of MS?

My Teacher Drinks Too Much Baileys

Answer 2

Muscle stiffness
Tired (fatigue)
Difficulty walking
Tingling (paraesthesia)
Muscle spasms
Blurred vision

Question 3

What is the M wave?

Answer 3

If we directly stimulate the peripheral nerve, there are motor neurones present therefore this may elicit a direct response in the form a muscle twitch represented by the M wave

Question 4

What is the H reflex?

Answer 4

If we stimulate the peripheral nerve, we may stimulate sensory nerves too, which will send an impulse up to the spinal cord, then to the muscle via the motor neurone. This is therefore a delayed motor response when compared to that of the M wave.

Question 5

What is the F wave?

Answer 5

If we provide a large enough stimulus to the nerve, we can send an impulse that travels from the motor neurone back to the spinal cord antidromically. It then turns around in the ventral horn, and travels back down the motor neurone to cause a small motor response.

Question 6

What do we use to confirm the central nature of MS?

Answer 6

Using transcranial magnetic stimulation

Question 7

What values do we need to calculate the central nature of MS?

Answer 7

PMCT, CMCT, (TMCT)

Question 8

What is TMCT?

Answer 8

Total motor conduction time, also known as the motor evoked potential latency. This is the total time taken for a stimulus to travel down the upper and motor neurones from the brain to the muscle

Question 9

What is PMCT?

Answer 9

Peripheral motor conduction time - the time taken for an impulse to travel from the spinal cord to the muscle. We calculate this by adding M wave latency to F wave latency, subtracting 1 and then diving by 2.

Question 10

What is CMCT?

Answer 10

This is the TMCT - PMCT. Meaning the time taken for an impulse to travel from the Brain to the spinal cord in the upper motor neurone.

Question 11

Why do we subtract 1 when calculating PMCT?

Answer 11

We assume that this is the time taken for the impulse to travel round in the spinal cord, from travelling antidromically to orthodromically.

Question 12

How are calculations indicative of central nature of MS?

Answer 12

If the TCMT is delayed, but the PMCT is normal, then we know that the CMCT is delayed, therefore indicative of demyelination. This confirms the central nature of MS.