Palmar conduction time of median and ulnar nerves of normal subjects and patients with carpal tunnel syndrome.

The wrist-palm conduction time for the median and ulnar nerves was determined using antidromic technique in thirty normal subjects. For the median nerve, the conduction time was 1.6 msec. to initial deflection from baseline and 1.7 msec. to peak of the initial negative deflection for the mean plus 2 SD. The median wrist-palm conduction time was then compared to the difference between the median and ulnar wrist-digit conduction times (mean plus 2 SD of 0.5 msec. measured either to initial deflection or peak negative deflection) in order to determine which technique aids more in the electrodiagnosis of patients with a presumptive clinical diagnosis of carpal tunnel syndrome but which normal distal sensory latencies. It was found in ten patients that the results of these two electrodiagnostic methods paralleled each other, and neither appeared more sensitive than the other in establishing the diagnosis.