Anterior Interosseous Nerve Syndrome

Anterior interosseous nerve syndrome (Kiloh-Nevin Syndrome) is the triad of weakness of the flexor pollicis longus, the flexor digitorum profundus of the index finger, and the pronator quadratus. It is a manifestation of neuropathy affecting either the anterior interosseous nerve itself (anterior interosseous neuropathy) or its fascicles more proximally within the median nerve or brachial plexus (pseudo– anterior interosseous neuropathy). Anterior interosseous neuropathy in the presence of normal anatomic variation of the anterior interosseous nerve must be distinguished clinically from pseudo–anterior interosseous neuropathy, which can present with telltale signs in addition to the signature weaknesses of anterior interosseous nerve syndrome. A history of penetrating injury mitigates toward early exploration and nerve repair. A history of sudden onset and rapid progression, particularly when accompanied by a prodrome of pain and fatigue, suggests the presence of a focal neuritis, which typically resolves completely within 6 to 12 months without surgical intervention. If no improvement is noted within 6 to 12 months or if the neurologic condition worsens, surgical exploration may be warranted. In the presence of untreatable injury to the anterior interosseous nerve, with permanent muscular atrophy, functional tendon transfers of the flexor digitorum superficialis of the ring or middle finger or of the brachioradialis may be helpful. Copyright © 2001 by the American Society for Surgery of the Hand