Objective: To investigate cutaneous sympathetic functions in carpal tunnel syndrome (CTS) using sympathetic sweat responses (SSwRs) and skin vasomotor reflexes (SVmRs).
Methods: In 29 hands (20 patients) with idiopathic CTS, SSwRs were recorded with a sudorometer from the thenar eminence, and SVmRs were used to measure cutaneous blood flow using a Doppler flowmeter placed on the index finger tip. Normal data were obtained from 15 volunteers of similar age.
Results: SSwRs or SVmRs were abnormal in 23 (80%) hands; SSwRs were absent in 38%, whereas SVmRs were abnormally decreased in 59%. Autonomic symptoms were present in 18 (62%) hands; finger edema (38%) and dry hand (35%) were frequent symptoms. Autonomic symptoms, and abnormal SSwRs and SVmRs did not correlate with results of nerve conduction studies.
Conclusions: Skin sudomotor or vasomotor sympathetic function is frequently impaired in CTS. Susceptibility to compression ischemia may be different in sympathetic unmyelinated and large myelinated fibers.