The anterior interosseous nerve syndrome.

Four cases of the anterior interosseous nerve syndrome, which were treated by neurolysis, are added to the sixty-five already described in the literature. The onset of symptoms is usually spontaneous and electrophysiological examination is of value in making the diagnosis. The most frequent cause of the entrapment is fibrous bands in the pronator teres muscle. The outcome after operation is better for complete lesions than for partial lesions which involve the thumb or index finger only.