Nerve conduction studies

Question 1

What disorders are NCS used to diagnose?

Answer 1

PNS only

Question 2

What is compound muscle potential?

Answer 2

Measures the nerve response, by the muscle innovated by the nerve

Question 3

What is sensory nerve action potential?

Answer 3

Measures the ability of sensory nerve fibres

Question 4

The F response refers to what?

Answer 4

When nerves fire, 3-5% fire back, and so are recorded slightly later

Question 5

If someone has demyelination, what would be seen on NCS?

Answer 5

Slowed conduction velocity

Question 6

If someone had axonal issues, what would be seen on NCS?

Answer 6

Reduced amplitudes

Question 7

What things can cause axonal damage?

Answer 7

Diabetes, alcohol, kidney disease, etc…

Question 8

What things can cause demyelination?

Answer 8

Conduction block, temporal dispersion

Question 9

What is conduction block?

Answer 9

Nervous transmission is blocked

Question 10

What is temporal dispersion?

Answer 10

Desynchronisation of muscle action potential due to different rates of conduction

Question 11

What is the normal conduction velocity for lower limbs?

Answer 11

Greater than 40 m/s

Question 12

What is the normal conduction velocity for upper limbs?

Answer 12

Greater than 50 m/s

Question 13

How do you know if amplitude isn’t normal?

Answer 13

If each side has a difference of over 50% in amplitude

Question 14

What happens to motor and sensory function, when the nerve root is damaged?

Answer 14

Have motor issues, but not sensory issues

Question 15

What happens to motor and sensory function when the dorsal root ganglion is damaged?

Answer 15

Will have sensory and motor issues

Question 16

What is EMG?

Answer 16

Complements NCG, can detect motor axonal loss (denervation), can tell if it’s active or chronic, and defines the location

Question 17

What part of the peripheral nerve is most vulnerable to metabolic stress?

Answer 17

The distal part