Bilateral flexor digitorum superficialis brevis of the little finger: a rare cause of carpal tunnel syndrome.

An anatomical variant of flexor digitorum superficialis brevis is an uncommon condition that may be a pitfall in diagnosing carpal tunnel syndrome, involving palpable mass and even characteristic symptoms. We present an unusual case of bilateral symptomatic carpal tunnel syndrome related to the presence of a flexor digitorum superficialis brevis muscle of the little finger, and a critical review of the literature.