Forearm pain secondary to compression syndrome of the lateral cutaneous nerve of the forearm.

This report describes a syndrome of compression of the lateral cutaneous nerve of the forearm (LCNF), the distal termination of the musculocutaneous nerve. Three patients presented with pain or numbness along the radial aspect of the distal forearm. There was a history of vigorous upper extremity exercise with elbow extension and arm pronation or resisted elbow flexion. Signs included: decreased sensation to pin and light touch in the distal forearm over the cutaneous distribution of the nerve; tenderness to palpation over the nerve where it pierces the deep fascia of the arm lateral to the bicipital tendon and proximal to the elbow crease; and decreased elbow extension with arm fully pronated. Electrodiagnostic studies revealed either a prolonged distal latency or decrease in amplitude of the evoked response of the lateral cutaneous nerve of the forearm in the symptomatic arm. Patients responded to treatment directed to the site of the lesion where the nerve pierces the deep fascia of the arm. Treatment methods included: restriction of upper extremity activity, use of a posterior splint to restrict elbow extension, transcutaneous electrical nerve stimulation (TENS), ultrasound, and surgical decompression. This syndrome may be readily differentiated from other causes of pain along the distal radial aspect of the forearm, making accurate diagnosis and treatment possible.