Multiple compression neuropathies and the double-crush syndrome.

Multiple compressions along a nerve have a cumulative effect on condition, both antegrade and retrograde. This nerve compromise renders the nerve more susceptible to a second source of compression. The proximal source of compression may be subclinical yet partially responsible for the cumulative compression syndrome. The primary "crush" may be anatomic or metabolic in origin. Strict attention to the patient's history and physical findings permit separation of the multiple compressions, making the choice of surgical decompression easier. Provocative testing and work simulation are important in examination, as is EMG testing. Complete medical evaluation can aid in diagnosing patients presenting with peripheral nerve compression and additional risk factors. Surgical decompression of a nerve with multiple levels of compression may not relieve all symptoms. Dynamic compressions in the work place and other nonsurgical types of compression must be identified so the prognosis for complete recovery is improved.