This chapter gives a current classification of diseases of peripheral nerve and then describes and illustrates the pathology of peripheral nerve, particularly from the perspective of the nerve biopsy. After a description of the clinical indications for the biopsy, an introduction to the general laboratory techniques, and a brief review of the normal morphology of peripheral nerve, the general reactions of peripheral nerve to injury (primary axonal degeneration and primary segmental demyelination) are described. Neuropathies can be separated into acquired and hereditary neuropathies. Inflammatory neuropathies include immunopathological disorders of unknown cause (e.g. inflammatory demyelinating polyradiculoneuropathy), neuropathies due to infectious agents (e.g. leprosy), or those associated with systemic vasculitis. Neuropathy also occurs secondarily, in association with hematological diseases and neoplasms. Metabolic (diabetic) and toxic neuropathies are subsequently discussed. The chapter also gives an account of the importance of incorporating recent advances in molecular genetics in the evaluation of hereditary neuropathies (i.e. hereditary motor and sensory neuropathies, hereditary sensory and autonomic neuropathies, and familial amyloid polyneuropathies).
