[Compression of the anterior interosseous nerve by Gantzer's muscle].

The authors report a case of incomplete anterior interosseous nerve syndrome due to mechanical compression by Gantzer's muscle. This accessory muscle induced an isolated paralysis of the flexor pollicis longus with a characteristic pinch attitude. No improvement was shown after six weeks of medical treatment. Recovery was rapid and complete following surgical relief of compression. Anatomical considerations, clinical features, and treatment are discussed.