Afferent pathways of sympathetic skin response in spinal cord: a clinical and electrophysiological study

Background: Sympathetic skin response (SSR) recording is an established tes t of sudomotor autonomic functions. However, knowledge of its pathways in s pinal cord is putative. Objective: This study involved subjects: with isola ted spinal cord lesions to evaluate the afferent pathways of SSR. Methods: Clinical examination was done according to standard neurological classifica tion of spinal cord injury. Electrophysiological evaluation included: (I) c onventional nerve conduction studies to exclude peripheral nerve lesions, ( 2) scalp somato-sensory-evoked potentials (SEP) with posterior tibial nerve (PTN) stimulation and (3) SSR recording from palm by stimulating supra orb ital nerve (SON) at forehead, and PTN at ankle. Subjects with absent SSR in palm to SON stimulation were excluded. In such patients, the afferent trac ts were considered abnormal when SSR was absent in palm on stimulation of P TN. Results: Among 37 subjects (age-28.1 +/- 12.8 years), the afferent trac ts of SSR were affected in 13. Sparing of afferent SSR tracts correlated wi th preservation of bladder sensations (P < 0.01). There was no correlation between SSR and SEP. Conclusions: Spinal cord lesions frequently involve af ferent tracts of SSR. Spinal afferents of SSR are closely related with trac ts of bladder sensations and are different from pathways for SEP. (C) 2001 Elsevier Science B.V. All rights reserved.