Understanding nerve conduction and electromyographic studies.

Electromyography has become an integral part of evaluation of disorders of the peripheral nervous system. This article reviews the principles, methodology, indications, and pitfalls of nerve conduction velocity and needle electromyographic studies. Normal patterns are described, and the significance of abnormal patterns is discussed. The value of different electrophysiologic tests in the assessment of nerve trauma, in entrapment neuropathy, and during peripheral nerve surgery is also addressed.