Neurographic Studies Before, after, and During Operation for Median Nerve Compression in the Carpal Tunnel

Fifty hands with clinical symptoms and signs of compression of the median nerve in the carpal tunnel have been electrophysiologically analysed pre- and post-operatively by measuring the sensory and motor conduction times in the median nerve over the wrist and by comparing the results with the corresponding sensory and motor conduction times in the radial and ulnar nerves of the same hand. The series was divided into four groups according to the severity of the electrophysiological pre-operative findings. All groups showed postoperative shortening of the conduction times for the median nerve parallelling clinical improvement.For electrophysiological diagnosis of distal median nerve compression it seems more adequate to compare the sensory and motor conduction of the median nerve with the radial nerve sensory conduction and the ulnar nerve motor conduction in the same hand than the use of fixed “normal” limits or using the other hand as control.During some operations, recordings of sensory conduction time and microneurographic studies showed an improvement of nerve conduction within 30 minutes of decompression.