Sonographic diagnosis of anatomical variations associated with carpal tunnel syndrome.

Bifid median nerve is an anatomic variation that occurs in about 18% of patients with symptoms suggestive of carpal tunnel syndrome and in about 15% of symptom-free subjects. Reversed palmaris longus is a rare anatomic muscular variation. The simultaneous presence of a bifid median nerve and a reversed palmaris longus has been very rarely described, usually during surgical exploration or in cadavers. We present two cases where ultrasound showed the presence of both abnormalities, allowing a correct diagnosis and influencing the treatment plan.