SYMPATHETIC SKIN-RESPONSES OF THE HAND IN NORMAL SUBJECTS - SHORTER LATENCY AT DISTAL PHALANX

We studied the conduction of the sympathetic skin response (SSR) in th e hands of 35 normal subjects by simultaneous recording at five sites. The mean latency of the SSR in all subjects increased from the wrist (W) to the middle phalanx (M), but the SSR latency at the distal phala nx (D) was shorter than that at the middle phalanx. The mean conductio n time and conduction velocity from W to M was 197.5 ms and 0.87 m/s, respectively, and that from W to D was 48.8 ms and 2.34 m/s, respectiv ely. For evaluation of the cause of the shorter latency at D, digital nerve blocking was performed in two subjects. The blocking of the vola r digital nerves at the proximal phalanx abolished SSR at M and D. It was postulated that the initiation or conduction of sudomotor nerve im pulse to the distal phalanx would be facilitated compared with those t o the other proximal sites in the hand. The SSR conduction time betwee n W and M may be a means of detecting alteration of sympathetic sudomo tor nerve activity. (C) 1997 Elsevier Science Ireland Ltd.