An examiner performing an NCS on a patient notes that the upper extremity nerve conduction velocities are about 5 to 10 meters per second faster than the lower extremity nerves. What is the correct interpretation of this finding?
A) This indicates a neuropathy affecting only the upper extremity nerves.
B) This is an abnormal finding likely caused by practitioner error in performance of the test.
C) This indicates a neuropathy affecting only the lower extremity nerves.
D) This is a normal finding.

Question

Quizplus · Accepted Answer

This is a normal finding. The nerve conduction velocities in upper extremity nerves are usually faster than those in lower extremity nerves due to the larger diameter of the nerves. This difference in velocity is known as the "length constant" and is a normal physiological difference.

An Examiner Performing an NCS on a Patient Notes That