Sympathetic skin response in carpal tunnel syndrome

Objectives: Sudomotor efferent nerve fiber function was studied in carpal tunnel syndrome (CTS). Methods: Bilateral median and ulnar sympathetic skin response (SSR) were recorded by sternal stimulation in 22 bilateral and 9 unilateral patients and compared with 21 healthy volunteers. Results: There was no significant difference between median and ulnar nerve SSR latency, amplitude or area. The median nerve SSR was not different from that of the controls. The median-to-ulnar ratios of SSR parameters were not different in patients and controls. However, the median-to-ulnar ratios of SSR amplitude and area were lower than normal in 3 out of 7 patients with normal nerve conduction whereas this abnormality was found in only 4 out of 46 patients with abnormal nerve conduction. Conclusions: Normal SSR results, even in patients with complaints related to sudomotor sympathetic dysfunction, indicate that the SSR does not seem to be a sensitive diagnostic method in CTS.