Evoked potentials are potentials that are derived from the peripheral or central nervous system. They are time locked with an external stimulus and can be influenced by subjective intentions. Evoked potentials have become increasingly popular for clinical diagnosis over the last few years. Evoked potentials from the visual system are used by ophthalmologists in order to localize the abnormalities in the visual pathway. The otologists are mainly involved in brainstem auditory evoked potentials, while the pediatricians, neonatologists, neurologists and clinical neurophysiologists make use of multimodal stimulation. The psychiatrists and psychologists, generally, examine the slow potentials such as P300 and CNV. Anesthesiologists use short latency somatosensory and visual evoked potentials in order to monitor the effectiveness of the anesthesia. Pharmaco evoked potentials are very promising measures for the quan tification of the effectiveness of drug action on the cerebral cortex. Urologists are more and more involved in pudendal somatosensory evoked potentials and in the intensive care unit evoked potentials are used in order to monitor the functional state of the central nervous system of the patient. This overwhelming number of examinations and exam ina tors clearly demonstrates the need for guidelines and standardization of the methods used. The evoked potential metholody is restricted by the relative poor signal to noise ratio. In many diseases this signal to noise ratio decrease rapidly during the progression of the illness. Optimal technical equipment and methodology are therefore essential."

Evoked potentials are potentials that are derived from the peripheral or central nervous system. They are time locked with an external stimulus and can be influenced by subjective intentions. Evoked potentials have become increasingly popular for clinical diagnosis over the last few years. Evoked potentials from the visual system are used by ophthalmologists in order to localize the abnormalities in the visual pathway. The otologists are mainly involved in brainstem auditory evoked potentials, while the pediatricians, neonatologists, neurologists and clinical neurophysiologists make use of multimodal stimulation. The psychiatrists and psychologists, generally, examine the slow potentials such as P300 and CNV. Anesthesiologists use short latency somatosensory and visual evoked potentials in order to monitor the effectiveness of the anesthesia. Pharmaco evoked potentials are very promising measures for the quan tification of the effectiveness of drug action on the cerebral cortex. Urologists are more and more involved in pudendal somatosensory evoked potentials and in the intensive care unit evoked potentials are used in order to monitor the functional state of the central nervous system of the patient. This overwhelming number of examinations and exam ina tors clearly demonstrates the need for guidelines and standardization of the methods used. The evoked potential metholody is restricted by the relative poor signal to noise ratio. In many diseases this signal to noise ratio decrease rapidly during the progression of the illness. Optimal technical equipment and methodology are therefore essential."

J.P.C. de Weerd Evoked potentials are the electrical voltage fluctuations which can be recorded from parts of the nervous system in response to stimulation of sensory modalities. One may distinguish between evoked potentials from the peripheral and the central nervous system. For the latter type a further subdivision can be made into spinal, brainstem, and cortical evoked potentials, according to the (assumed) structures from which the responses derive. Another possible subdivision can be made with respect to the specific sensory ffiodality which is stimulated. Accordingly, one has auditory, somatosensory, visual, gustatory and olfactory evoked potentials. At the present time, the former three types of evoked potentials are the ones that are commonly measured in diagnostic procedures. Yhe corresponding sensory systems are relatively easy to stimulate, for example by means of an acoustic click, abrief electrical shock or a reversing light pattern. In contrast, stimulation of the olfactory and gustatory systems has proven to be technically and physiologically difficult and research in these areas is still in an early stage.