The peripheral nervous system is the portion of the nervous system outside of the brain and
spinal cord. It includes the 12 pairs of cranial nerves, 31 pairs of spinal nerves and
their branches, nerves responsible for sensation and maintenance of normal body functions
(sympathetic and parasympathetic nerves).
Years of research using clinical examinations, microscopic examinations, and
electrophysiology have made the peripheral nervous system the best-studied and most
available portion of the nervous system. However, even with all of the extensive studies
conducted on the peripheral nervous system, many conditions remain unclassified.
The EMG Laboratory at the NIH concentrates on studying disorders of the peripheral nervous
system. This protocol was designed to allow the EMG Laboratory to;
I) Learn more about established diseases of the peripheral nervous system
II) Identify and characterize new diseases of the peripheral nervous system
III) Assess current techniques in the diagnosis of diseases of the peripheral nervous system
IV) Refine old methods and develop new ones for the diagnosis of diseases of the peripheral
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.
Patients with disorders of the peripheral nervous system, including neuropathies,
myopathies, or defective neuromuscular transmission.
Normal age-matched volunteers, including some from within a neurologic population.