Sympathetic skin response and regeneration of sudomotor fibers after complete division of peripheral nerves.

Sympathetic skin responses (SSRs) were studied in hands of patients during regeneration of their median or ulnar nerves following complete severance and suture. The SSRs were elicited with electrical stimuli presented to the forearm of the normal side and recorded between the dorsum of the hand and three sites in the innervation area of the two nerves. The amplitude and area of the SSRs were compared to those obtained at the identical points on the uninjured hand. The responses were followed up for 16 months at 1-1.5-month intervals in a group of 6 adults and for 14 months at monthly intervals in 7 children. After an initial absence, the SSRs appeared after about 4 months postoperatively at the most proximal site in the adults and 2-3 months in the children. It progressed subsequently over a 14- or 16-month observation period to less than 50% of the normal side in the adults and to close to 100% in children, fastest and most complete for the proximal recording site, considerably earlier in the children. End-stage recovery studied in another group of 14 adults and 7 children 2-7 years postoperatively reached an average of 80-100% at the most proximal recording site in most adults and children. The intermediate and the distal sites showed less complete return of the SSR. The method of recording SSRs is considered suitable to follow regeneration of the sudomotor fibers in the cut and sutured nerves of the hand.