This is part of a 2-volume work in which the authors treat the three main branches of clinical neurophysiology - peripheral neurophysiology, evoked potentials and electroencephalography - in a consistent and integrated way with emphasis on a clear exposition of practical details of how and why each investigation is done. Their aim is that the reader should understand exactly how to choose and to undertake appropriate investigations, and how to interpret the findings in the light of the latest evidence-based studies. Using historical evidence and illustrative case reports, they address the scientific principles, both biological and electrical, recording techniques, the development and characteristics of electrical potentials in normal subjects, and the ways in which these are disturbed by physical factors or disease. This foundation should enable the reader to interpret recordings from first principles. The main clinical sections are set in the context of typical referral problems or disease groups, showing how the appropriate sequence of investigations and their interpretation help in diagnosis or surveillance of the patient's condition.