Visual Evoked Potentials

Abstract

This chapter discusses flash-induced visual evoked potentials (VEPs) and pattern-reversal visual evoked potentials (PRVEPs), their clinical utility, method of acquisition, and standard recording protocol. It describes the major components of flash VEP and PRVEP, their common morphologic variations, and influence of various subject-related and technical factors on these responses. Detail descriptions are provided of common PRVEP abnormalities and their interpretation and correlation with dysfunction at specific levels of visual pathways. Even though hemifield PRVEPs are less frequently performed clinically, they are adequately covered for those who may like to pursue them further. Major neurological and ophthalmological conditions associated with VEP abnormalities are also described with a detailed discussion on the abnormal patterns seen in multiple sclerosis, optic neuritis, and traumatic and anoxic coma. The methodology to differentiate between organic versus functional types of blindness is discussed. More than 30 figures and 10 tables illustrate various PRVEP and flash VEP characteristics and abnormalities. Six clinical cases are included at the end of this chapter and are discussed under the following headings: reason for study, technical summary, VEP findings, interpretation, and discussion. The chapter provides the referring physician a recommended method of writing VEP reports.