An Unusual Localization for A Proximal Median Nerve Lesion: Case Report and Review of the Literature

We report a patient who presented with the classical picture of carpal tunnel syndrome, but had a normal nerveconduction study across the wrist. She later developed weakness of the flexor pollicis brevis muscle. Extensive nerveconduction studies confirmed a lesion of the motor fibers of the median nerve at the distal part of the medial cord, beforethe anastomosis with the lateral cord and distal to the branch that becomes the ulnar nerve. The patient did not reportany trauma or fall or compression or traction or surgery on the arm. All investigative study failed to reveal an etiology.Repeated nerve conduction study confirmed the lesion. After a course of steroids, the patient was cured and the nerveconduction studies normalized. We describe an idiopathic, proximal median nerve lesion with a rare localization.