Anomalous muscles within the first dorsal extensor compartment of the wrist.

A 73-year-old woman presented with a 12-month history of a tender first dorsal extensor compartment of her right wrist along with swelling which extended proximally. Caring for her grandchildren exacerbated her pain, and rest relieved it. Over a 2-month period, two injections and splint immobilization failed to provide pain relief and swelling reduction. An ultrasound showed anomalous muscles within the first dorsal extensor compartment. Surgical release of the first compartment showed the abductor pollicis longus and extensor pollicis brevis tendons flanked by muscles within an inflamed sheath. Releasing the compartment resulted in complete pain relief. Anatomic variations within the first dorsal extensor compartment have been reported, but there has been no report on double anomalous muscles within the compartment. The details of the case, utility of ultrasound, and a brief review of the literature are described.