The Influence of Stimulation Site on the Conduction Study of Palmar Cutaneous Branch of Median Nerve

ABSTRACT

OBJECTIVE: Nerve conduction study of palmar cutaneous branch of median nerve is infrequently evaluated in spite of its importance because of perceived technical difficulties. This study reports the different nerve conduction responses of palmar cutaneous branch of median nerve by change of stimulation site. METHOD: Conduction study of palmar cutaneous branch of median nerve was performed in 42 normal individuals stimulated at the site of 7 cm proximal to the recording electrode. Results were compared to those of stimulated at the site of 10 cm proximal to the recording electrode with t-test by SPSS 7.5. RESULTS: Values of conduction study stimulated at the site of 10 cm proximal to the recording electrode were 2.37+/-0.48 msec (mean+/-SD) for peak latency, 15.67+/-8.31 micro V for amplitude and 34.52+/-5.97 mA for supramaximal intensity.Those values stimulated at 7 cm proximal were 1.72+/-0.33 msec for peak latency, 24.48+/-11.41 micro V for amplitude and 12.82+/-2.18 mA for supramaximal intensity. Amplitude stimulated at the site of 7 cm was significantly larger than that stimulated at the site of 10 cm (p<0.01). Supramaximal intensity stimulated at the site of 7 cm was significantly smaller than that stimulated at 10 cm (p<0.01). CONCLUSION: The different stimulation site influences on the nerve conduction study of the palmar cutaneous branch of median nerve. Conduction study of palmar cutaneous branch of median nerve with stimulation at 7 cm proximal is a more reliable and convenient method compared to 10cm proximal in respect of larger amplitude and smaller supramaximal intensity.