EMG General

Question 1

What is an F wave?

Answer 1

CMAP (motor response only)
- andidromically stimulating motor nerve-> time for stimulus to travel to spinal cord and return orthodromically to muscle

Question 2

What is an H reflex?

What is it usually used to diagnose?

Answer 2

Monosynaptic stretch reflex
CMAP evoked by stimulating sensory fibers-> DRG -> Ant horn -> a-motor neuron -> muscle
Mostly used to dx S1/C7 root lesions (FCR- median, and Soleus-tibial)
Submaximal stimulus

Question 3

What kind of nerve injury is neuropraxia?

Answer 3

Mild- aka conduction block

Reversible blockage of impulse conduction across affected segment

Question 4

What type of nerve injury is axonotmesis?

Answer 4

Axon is physically disrupted, with preservation of endoneurium. Often from severe compression or traction injury, reversible

Question 5

What type of nerve injury is neurotmesis?

Answer 5

Complete disruption of axon and all supporting structures, poor prognosis