1. The median nerve is stimulated percutaneously (1) at the wrist and (2) in the antecubital fossa with the resultant compound muscle action potential recorded as the potential difference between a surface electrode over the thenar eminence (arrow) and a reference electrode (Ref.) more distally. Sweep 1′ on the display depicts the stimulus artifact followed by the compound muscle action potential. The distal latency, A′, is the time from the stimulus artifact to the take-off phase of the compound muscle action potential and corresponds to conduction over distance A. The same is true for sweep 2′, where stimulation is at 2 and the time from the artifact to the response is A′ + B′. The maximum motor conduction velocity over segment B is calculated by dividing distance B by the time B′.
Source: Chapter 45. Electrophysiologic and Laboratory Aids in the Diagnosis of Neuromuscular Disease, Adams and Victor's Principles of Neurology, 10e
Citation: Ropper AH, Samuels MA, Klein JP. Adams and Victor's Principles of Neurology, 10e; 2014 Available at: Accessed: October 15, 2017
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