Making sense of electrophysiological testing of the nervous system

ELECTROPHYSIOLOGICAL testing involves the use of electrical recording to investigate physiological function or dysfunction within the body. While the use of electrocardiography to assess cardiac function is commonplace, there is a range of techniques that can be used to evaluate the nervous system that is less well known. These electrophysiological tests are not widely available in general veterinary practice; indeed, their performance and interpretation is often considered as one of the 'black magic' arts of veterinary neurology, itself a topic much feared by many within the profession. However, if used correctly, electrophysiology can prove invaluable in the investigation of the nervous system to help localise lesions and establish a diagnosis. This article describes the four most common electrophysiological tests of the nervous system ‐ electromyography, nerve conduction studies, brainstem auditory evoked response testing and electroretinography. It discusses how these techniques may be used to answer specific questions relating to the function of the nervous system and outlines the indications and limitations of each.