Anterior interosseous nerve syndrome due to aneurysm of arterio-venous fistula.

Weakness of the thumb, index, middle fingers developed over several days in a 48-year-old man with end-stage renal disease and an arteriovenous fistula in that arm. A large thrombosed aneurism was found and was shown to be compressing the anterior interosseous nerve (a branch of the median nerve). Surgical resection was followed by marked neurologic improvement. This syndrome is compared with two other median nerve compression syndromes (the pronator and carpal tunnel syndromes).