[Use of visual evoked potentials in neurology--a review. I]

In 1972, Halliday and co-workers [13] inaugurated the rotary mirror method for producing the visually evoked potential (VEP) by means of pattern reversal. The so-called pattern reversal VEP (PRVEP) is at present frequently obtained by means of a television monitor (TV stimulation) or light-emitting diode system (LED system). Independent of its special advantages and disadvantages, the stimulation by means of these systems as compared to the simple flash stimulation potentials seems to evoke with considerably better reproduceable latency indices, which enables a clearer separation of normal and pathological values. This is in particular true of the P100 component, which is the most prominent part of the VEP. The size of the individual squares of the chess-board pattern, of the whole stimulus field, the brightness and the intensity of the contrasts exert an influence on amplitudes and latencies of the PRVEP. The hitherto lacking standardisation of the recording technique makes it necessary that laboratory develops its own standard values. The domain of the PRVEP at the time being is the demonstration of demyelinising processes in the region of the optical nerve. That is why the PRVEP plays an important role in the diagnosis of multiple sclerosis, especially in subclinical processes and seemingly only spinal symptoms. Extension of the P100 latency, however, are not specific of multiple sclerosis and can also be caused by other lesions of the optical nerve or by a delayed maturing of the neuronal systems generating the VEP.