Electrophysiological changes after severance of the C7 nerve root.

Since 1986, contralateral C7 root transfer has been used to treat brachial plexus root avulsions in our hospital. We performed post-operative electrophysiological examinations of the healthy-side limb in the first 27 patients. Electromyography and nerve conduction studies on the healthy side demonstrated mild abnormalities only of individual limb muscles in a few cases. These changes mostly recovered during the follow-up period. In the measurement of radial nerve motor conduction, median nerve sensory conduction and somato-sensory evoked potentials, we found that the amplitude of the median nerve sensory conduction alone was slightly lower than that of the control group (p < 0.05). The results showed that severance of C7 caused no permanent functional damage to the upper limb.