Combined with careful clinical examination, electrophysiology and histopathology have rendered the peripheral nervous system the best studied and most accessible level of the nervous system. But even after intensive diagnostic evaluation of peripheral neuropathies in large diagnostic centers, 24 to 70% of disorders remain unclassified. Analogous statistics for disorders of muscle and neuromuscular transmission are not known but probably similar, if not worse. Clearly, detailed diagnostic characterization of disorders of the peripheral nervous system is the first stage in clinical intervention.

Currently, the EMG Laboratory at the NIH offers complete clinical, electrophysiologic, and, when appropriate, pathologic evaluations on all referrals from the other Branches and Institutes. Since these referrals come primarily from within the NIH, most disorders are secondary to other systemic disease. This protocol is designed to extend the services to direct referrals of primary disorders of the peripheral nervous system. The purposes are first, to learn more about established diseases; second, to identify and characterize new diseases; third, to assess current methodologies and technologies; and fourth, to refine old methods and develop new ones. Under this umbrella protocol, individual cases and clinical series can be investigated.