Effect of interelectrode recording distance on morphology of the antidromic sensory nerve action potentials at the finger.
In 15 normal subjects, antidromic median sensory compound nerve action potentials (SCNAPs) were recorded supramaximally from the middle finger with ring electrodes, using different interelectrode recording distances. The onset latencies were identical in all recording instances. The peak latency and amplitude of the major negative deflection continued to increase with increasing interelectrode distance. At and beyond a 4 cm interelectrode recording separation, they both achieved maximum values and did not increase further. On the other hand, the duration and area did continue to increase with increasing interelectrode separation. These findings suggest that in normal individuals, the true onset latency, peak latency, and amplitude are well reflected in the median SCNAP when it is recorded with an interelectrode distance of 4 cm or more at the finger; thus, they can easily be standardized. The SCNAP duration and area, however, are more variable since they both continue to change with increasing interelectrode recording separation without approaching a saturation value.
Wee
A S
AS
Department of Neurology University of Mississippi Medical Center, Jackson.
Ashley
R A
RA
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D004594:Electrophysiology; D005385:Fingers / Q000502:physiology*; D006801:Humans; D009431:Neural Conduction / Q000502:physiology*