Pronator Syndrome

13 Pronator Syndrome

Kevin D. Plancher

History and Clinical Presentation

A 35-year-old woman presents to our office with symptoms of forearm discomfort consisting of fatigue-like pain and numbness in her hand. She works long hours on a computer and reports that this repetitive activity is what reproduces the symptoms in her right arm; however, she denies any symptoms at night. The condition has been gradually getting worse.

Physical Examination

The patient presents with symptoms of general forearm pain in addition to paresthesias and hypersthesia in the thumb, index finger, long finger, and radial half of the ring finger. There is pain on flexion of the long finger at the proximal interphalangeal (PIP) joint. Sensory symptoms are also present over the thenar eminence in the distribution of the palmar cutaneous nerve.

Patient experiences pain on palpation of the median nerve in the proximal forearm. In addition, the pronator teres muscle can be tender, firm, or enlarged. Tinel’s sign is present on the nerve site just distal to the elbow and paresthesias increase with mild compression of the proximal muscle mass of the pronator teres. Phalen’s test is negative.

Diagnostic Studies

Electrodiagnostic tests are suggestive, but not always diagnostic. Although slowing will often show in the forearm, it does not always show in the carpal canal. The threshold testing with Semmes-Weinstein monofilaments may reveal decreased sensibility over the distribution of the median nerve.

Needle electromyography (EMG) may be useful if fibrillations, positive sharp waves, and reduced interference patterns are noted in the pronator quadratus and flexor pollicis longus (FPL). It is important to note that the EMG does not differentiate median nerve lesions at the pronator teres from those more proximal.