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.