Pathology of Peripheral Nerves

This chapter describes and illustrates the pathology of peripheral nerve as it may be evaluated on nerve biopsy. After a description of the indications for the biopsy, of the special techniques commonly used, and of the normal anatomy 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 immunopathologic disorders of unknown cause (inflammatory demyelinating polyradiculoneuropathy) and neuropathies due to infectious agents (leprosy) or associated with systemic vasculitis. Several neuropathies occur in association with hematologic diseases and neoplasms. Metabolic (diabetic) and toxic neuropathies are frequent. Recent advances in molecular genetics have greatly enhanced the understanding of hereditary neuropathies. These include hereditary motor and sensory neuropathies, hereditary sensory and autonomic neuropathies, and familial amyloid polyneuropathies.