Chapter 24 - Median Neuropathy

Abstract

Although the most common entrapment of the median nerve is at the wrist at the carpal tunnel (carpal tunnel syndrome), there are entrapment sites more proximal to this area, which are much less common in frequency, but important to recognize. The two entities are pronator teres syndrome, and anterior interosseous syndrome. Symptomatologically in the pronator teres syndrome, one usually relates to pain in the forearm region secondary to repetitive motion of the elbow, forearm, and wrist or hypertrophy of the forearm musculature with possible tingling, clumsiness or weakness. The anterior interosseous nerve syndrome has similar acute pain in the forearm, which may be associated with trauma, pure motor involvement, and may show the typical inability to perform the “OK” sign. Diagnostic ultrasound, and MRI studies can exclude other causes of pathology. Electrodiagnostic testing may show some nerve conduction abnormalities of the median nerve with the pronator teres syndrome. Needle electromyography typically shows the instability/dennervation in the distal muscles of the median nerve with sparing of the pronator teres muscle in the pronator teres syndrome. The flexor pollicis longus, and flexor digitorum profundus of the 2nd digit show evidence of muscle instability/dennervation in the anterior interosseous syndrome. Treatment with conservative physical therapy can resolve symptoms in 6-8 weeks although surgical intervention maybe necessary in anterior interosseous syndrome if the cause is related to trauma and depending on the severity of the condition clinically and electrodiagnostically.