2. Peripheral evoked potentials

This self-directed learning module highlights advances in the clinical evaluation of nerve conduction through peripheral evoked potentials. It is a section of the chapter on electrodiagnosis for the Self-Directed Medical Knowledge Program Study Guide for practitioners and trainees in physical medicine and rehabilitation. This section covers instrumentation, neurophysiology of nerve conduction and neuromuscular transmission, techniques of performing the studies, and clinical applications. Technologic improvements in amplifiers and storage systems have made detailed measurement of sensory and motor responses a routine clinical procedure. The interaction of membrane action potentials and volume conduction is explained, and the effect of abnormal neuromuscular transmission on evoked responses is analyzed. Skin surface techniques for stimulation and recording of potentials are compared with transcutaneous needle techniques. Clinical examples are presented to clarify the usefulness of these studies in evaluating suspected problems, including localized compression neuropathies, peripheral axonopathies, demyelinating neuropathies, and disorders of neuromuscular transmission.