QUESTION: The AMA Guides, Sixth Edition, states on page 445, “For impairment rating purposes, upper limb nerve conduction studies must be done with a limb temperature maintained at or above 32°C. The limb temperature must be stated in the report.” Additionally, on page 409, it is stated, “The studies (electrodiagnostic) must be performed in accordance with established standards.” Why are these statements important?
ANSWER: To recognize abnormal nerve function on nerve conduction tests, the minimum requirement is that conduction be slower than normal. The testing equipment measures time between stimulus and response (latency). The examiner inputs the approximate distance over which testing occurred into the computer, permitting the computer to calculate conduction velocity.
In the upper limb, definitions of normal conduction for latency (time) and speed (conduction velocity) were derived assuming an upper limb temperature of ≥32°Celsius....
