Upper extremity tourniquet effects in carpal tunnel release.

We studied the presence and extent of upper extremity denervation in limb muscles after surgical release of the carpal tunnel. Sixty consecutive patients were randomly assigned to have the procedure performed with (31 patients) or without (29 patients) tourniquet application. Cervical paraspinal and upper extremity muscles were examined electromyographically 3 weeks before and 3 weeks after carpal tunnel release. Three weeks after the operation 77% of the patients in the tourniquet group had denervation in other than thenar muscles. Only one patient in the control (no tourniquet) group had similar electromyographic abnormalities after surgery. Tourniquet time and pressure did not vary significantly between those patients with or without postoperative forearm denervation. Mean operative time for the tourniquet and control groups was nearly identical. These findings indicate that upper extremity tourniquet application results in subclinical, temporary changes in the muscles of the forearm, probably on the basis of nerve changes and denervation.