Radial nerve entrapment by the lateral intermuscular septum after trauma.

Radial nerve palsy is associated with humeral shaft fractures, usually occurring at the time of injury but sometimes occurring later. We report on a case in which a progressive radial nerve palsy occurred three months after a fracture; on exploration, the nerve was found to be trapped by the lateral intermuscular septum. It is important to recognize progressive radial nerve palsies or late presentations, because they often represent chronic compression and a delay in exploration may be detrimental to the return of nerve function.