The elbow region is the most common site at which the ulnar nerve is prone to a localized neuropathy and early recognition of the cubital tunnel syndrome is important because of its successful response to simple operative decompression. Diagnosis is made on the basis of history, neurologic finding, electromyography and nerve conduction studies. First of all, comparison of the ADQ muscle action potential with stimulation proximal and distal to the ulnar groove has been suggested to confirm the diagnosis, but we have no standard value in healthy Korean and its normal variation.

The present study was undertaken to determine variation of amplitude of evoked action potential and conduction velocity of arm, across elbow and forearm segments. We have studied the segmental ulnar motor and sensory nerve conduction around the elbow in 79 healthy Korean adults, 53 male and 26 female, aged from 17 to 59 years. We have performed this study with elbow position 70 degree flexed and antidromic sensory recording.

The results were as follows;

1)The mean distal latency of ulnar NAP was 2.41±0.31 msec in motor and 3.23±0.26 msec in sensory.

2) The mean NCV of arm, across elbow, forearm segment were 74.06±8.00 M/sec, 62.82±7.29 M/sec, 61.61±6.58 M/sec in motor and 77.09±6.05 M/sec, 66.62±6.25 M/sec, and 63.81±6.23 M/sec in sensory, respectively, with no significant difference between across elbow and forearm segment.

3) The difference of NCV between Rt and Lt side in across elbow segment was less than 11.39 M/sec (95% Confidence Interval) in motor and 13.81 M/sec in sensory with no statistical significance.

4) The mean amplitude of distal ulnar motor NAP was 13.3±3.41 mV(above 6.48 mV; 59% C.I.) and the difference from proximal motor NAP(above elbow) was 2.35±2.19 mV(below 6.73 mV: 95% C.I.) with statistical significance.

5) The mean amplitude of distal ulnar sensory NAP was 33.63±13.27㎶(above 7.06㎶: 95% C.I.) and the difference from proximal NAP(above elbow) was 15.23±11.32㎶(below 37.87㎶: 95% C.I.) with statistical significance.

6) The proximal latency(AE-ADQ) of ulnar motor NAP was 7.01±0.82 msec(below 8.65 msec: 95% C.I.).