Paradoxical shortening of sympathetic skin response latency at distal recording sites.
OBJECTIVE
The purpose of this study was to investigate and to discuss the neurophysiological mechanism of paradoxical shortening of the sympathetic skin response (SSR) latency at distal recording sites.


METHODS
The latency and peak-to-peak amplitude of SSRs evoked by magnetic stimuli were analyzed. Eight active electrodes were placed on the palmar (anterior) and dorsal (posterior) sides of the hand (forearm) proximal to the distal arrangement.


RESULTS
SSRs from two palm sites had significantly shorter latencies and larger amplitudes than the SSRs at the other six sites, including the proximal sites of the forearm.


CONCLUSIONS
This finding indicated that the SSR latency at different sites was not linearly prolonged as the distance of the recording sites from the proximal to distal areas increased. The paradoxical shortening of the latency and the large amplitude of the SSR from the palm can be explained by a recent model of the equivalent current dipole caused by the Na+ concentration gradient. The high density of sweat glands in the palm possibly produced the present findings.


CONCLUSIONS
We should carefully interpret the sudomotor conduction velocity derived from latency difference between two sites, especially for thermal and emotional sweating.
Toyokura
Minoru
M
Department of Rehabilitation Medicine, Tokai University Oiso Hospital, 21-1 Gakkyo, Oisomachi, Nakagun, Kanagawa 259-0198, Japan. toyokura@juno.dti.ne.jp
D000328:Adult; D000704:Analysis of Variance; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation; D006185:Habituation, Psychophysiologic / Q000528:radiation effects; D006225:Hand / Q000294:innervation; D006801:Humans; D008280:Magnetics; D008297:Male; D011930:Reaction Time / Q000502:physiology*; D012867:Skin / Q000294:innervation*; D012879:Skin Physiological Phenomena / Q000528:radiation effects; D013564:Sympathetic Nervous System / Q000502:physiology*; D055815:Young Adult