Radial nerve entrapment in the upper arm as a cause of lateral arm pain: a report of four cases.

Four patients with no history of trauma presented with lateral arm pain, local tenderness, and a tingling sensation at the distal end of the arm when the radial nerve was percussed in the mid-third of the upper arm (Tinel's sign), but no clinical or subjective signs of muscular weakness. They were treated by decompression of the radial nerve in the fibrous canal proximal to the lateral intermuscular septum. Three of the patients had a complete or pronounced reduction in pain, while the fourth had only a slight improvement. Non-traumatic radial nerve entrapment in the upper arm may be the cause of lateral arm pain without clinical signs of muscular weakness.