Median Nerve Compression in the Proximal Forearm

ABSTRACT

Median nerve compression causing symptoms can occur not only at the wrist within the carpal tunnel but also in the proximal forearm. Compression neuropathy of the median nerve in the proximal forearm has been called pronator syndrome, based on the premise that the most common site of compression occurs from the pronator teres muscle.

The records of 24 patients (32 total limbs; 10 limbs had previous carpal tunnel release) who underwent surgical median nerve decompression in the proximal forearm were retrospectively reviewed. Chief complaints included paresthesias of the median nerve innervated digits (22 of 24 patients), dull aching pain in the forearm (13 of 24 patients), and paresthesias of the palmar or thenar regions (7 of 24 patients). The most common physical examination findings were a positive pronator compression test and a positive Tinel’s sign. An abnormal nerve conduction test was detected in 21 of 32 upper extremities.

The decision to perform surgery was based on a combination of history, physical examination, and nerve conduction studies. Intraoperatively, the most significant sites of proximal compression were: flexor digitorum sublimis (16), lacertus fibrosus (8), flexor digitorum sublimis/pronator teres (7), pronator teres (4), vascular leash (1), ligament of Struthers (1), and Gantzer’s muscle (1). Of the 32 median nerve decompressions, 19 underwent simultaneous release of the carpal tunnel. Postoperative follow-up revealed return to normal sensation and symptom relief in 28 of 32 limbs and symptom recurrence in 4 of 32 limbs.

Our findings demonstrate that the flexor digitorum sublimis and not the pronator teres may provide the most common site of proximal median nerve compression and that the “double crush” phenomenon requiring decompression of the proximal and distal nerve sites may be necessary for effective symptom relief.