232 - Aberrant Course of the Median Nerve at the Wrist causing Intermittent Paresthesia

Ultrasound identified an aberrant course of the median nerve at the wrist, which influenced subsequent diagnosis and management.

Case Description:

A 23-year-old female with a history of Ehlers-Danlos syndrome presented for electrodiagnostic evaluation of left hand pain and paresthesias. Electrodiagnostic testing revealed no evidence for a left median mononeuropathy at the wrist, left ulnar mononeuropathy at the elbow, or left cervical radiculopathy. However, it was noted that stimulation of the median nerve at the wrist for both the median sensory and median motor nerve conductions required over double the amount of milliamps compared to the ulnar sensory and ulnar motor nerve conductions as well as the superficial radial sensory nerve conduction. Ultrasound showed a bifid median nerve traveling radial to the flexor carpi radialis (FCR) tendon instead of the typical course in between the FCR tendon and the palmaris longus tendon. There were no areas of focal median nerve enlargement. With wrist flexion, the median nerve moved inferior to the FCR tendon and reproduced some of her hand paresthesias.

Discussions: This case demonstrates the value of utilizing ultrasound during electrodiagnostic testing. Without the use of ultrasound, no etiology for her symptoms would have been identified. These findings could influence subsequent management. In addition, the ultrasound findings explained discrepancies encountered during performance of nerve conduction studies.

Conclusions: Using ultrasound in conjunction with electrodiagnostic testing can provide key information in the evaluation of the nerve disorders, particularly in patients with anatomical variations.