Entrapment Neuropathies
John D. England, M.D.

Introduction

The term entrapment neuropathies refers to isolated peripheral nerve injuries occurring at specific locations where a nerve is mechanically constricted in a fibrous or fibro-osseous tunnel or deformed by a fibrous band. In some instances the nerve is injured by chronic direct compression, and in other instances angulation or stretching forces cause mechanical damage to the nerve. Common examples of nerve compression in a fibro-osseous tunnel are the carpal tunnel syndrome and ulnar neuropathy at the cubital tunnel. Angulation and stretch injury are important mechanisms of nerve injury for ulnar neuropathies associated with gross deformity of the elbow joint ("tardy ulnar palsy") and neurogenic thoracic outlet syndrome. Recurrent compression of nerves by external forces may also cause focal nerve injuries such as ulnar neuropathy at the elbow and deep branch lesions of the ulnar nerve in the hand. Although these latter neuropathies do not satisfy the strict definition of "entrapment neuropathies", they are often considered in a discussion of the topic. The pathological features of all of these isolated neuropathies include a varying combination of focal demyelination and wallerian axonal degeneration (1, 2). (Click here to download entire article)