Isolated abductor digiti minimi palsy--an unusual case of Guyon's canal compression.

We present a case of isolated Abductor Digiti Minimi (ADM) palsy caused by an anomalous branch from the ulnar artery. Electrophysiology suggested selective involvement of the motor branch to the ADM in the Guyon's canal. Surgical exploration revealed an anomalous branch of the ulnar artery causing a pincer effect on the nerve to the ADM. Division and ligation of this branch effectively decompressed the nerve and the patient recovered satisfactorily. This report highlights the need to consider vascular aberrations as a differential diagnosis for ulnar neuropathy in Guyon's canal.