Electromyographic studies in peripheral nerve injuries.

In every aspect of management of peripheral nerve injury, needle electromyography and nerve conduction velocity studies can give the clinician valuable objective information to supplement clinical findings. Comprehensive EMG studies in the fourth week after injury are helpful in diagnosing nerve injury, in localizing the site of injury, and in estimating the extent of injury. (In medicolegal situations, the first EMG study should be done within the first five days.) To assess the need for surgical exploration in cases of severe nerve injury, another EMG evaluation should be done eight weeks after injury. If there is no clinical and electrophysiologic evidence of improvement, surgical exploration is recommended. At exploration, the simple study of nerve potential on the exposed nerve in continuity will help the surgeon decide between neurorrhaphy and neurolysis. To assess regeneration, EMG study eight weeks after repair is recommended. When objective evidence of clinical improvement is desirable, serial EMP studies at intervals of four months are in order. To assess the recovery or residual effects of a lesion, final EMG study is recommended 18 months after injury or repair.