Clinical and electrophysiological presentation of pronator syndrome

Median neuropathy at the elbow (pronator syndrome [PS]) is rare compared to compression at the wrist. We sought to evaluate the clinical/electrophysiological parameters of this focal neuropathy. Between 1992 and 2002, we retrospectively reviewed records of eighty-three limbs in seventy-two patients with PS. Electrodiagnostic data as well as clinical symptoms, physical findings, demographic information and treatment modalities were examined. The main symptoms were forearm pain, numbness and weakness. One patient (two limbs) had nocturnal paresthesias. Twenty-five limbs (30%) showed decreased median forearm velocity. Fifty-four (65%) had abnormal median sensory studies of either abnormal conduction velocity or amplitude. Needle exam showed an abnormality of at least one median innervated muscle, abductor pollicis brevis, flexor carpi radialis, or pronator teres, in 70% (58/83). Sixteen limbs were identified as having undergone surgical decompression. In the surgical group, 10/16 (63%) were found to have constriction with a band which was released during surgery. Eight of the sixteen patients who underwent surgery were found to have documented improvement. Eleven patients (13%) had undergone previous surgery for Carpal Tunnel Syndrome (CTS) without benefit. The clinical and electrophysiological features of PS are quite different from patients with CTS. Proper localization is crucial to treatment options. Surgery can provide benefit in selected cases.