24 - Radial Neuropathy

Abstract

The radial nerve is studied less frequently than the median and ulnar nerves in the electromyography laboratory. Nevertheless, entrapment of the radial nerve does occur, often affecting the main radial nerve either in the upper arm or axilla. The most common site of entrapment is at the spiral groove, where the nerve lies juxtaposed to the humerus. External compression results in the well-known clinical syndrome of a “Saturday Night Palsy,” wherein the patient presents with a wrist and finger drop. Isolated lesions of the terminal divisions of the radial nerve in the forearm, the posterior interosseous nerve, and the superficial radial sensory nerve also occur. Although radial motor nerve conduction studies are technically demanding, the electrophysiologic evaluation of radial neuropathy usually is able to localize the lesion, assess the underlying pathophysiology, and provide useful information regarding severity and subsequent prognosis. In addition, similar to other entrapment neuropathies, neuromuscular ultrasound is often very useful in adding specific anatomic information regarding the location and etiology of a radial neuropathy.