Criteria for the evaluation of nystagmus.

Suitable criteria are reported for the analysis and evaluation of the caloric nystagmus as well as for the differentiation of the pathological from the physiological spontaneous nystagmus. Relative values for the difference and the directional preponderance, related to the intensity of the total reaction, seem to be the most appropriate criteria for the evaluation of the caloric test. The values obtained in patients should be compared with interquantile areas of healthy subjects. The parameters 'maximum slow phase velocity' and 'maximum frequency' seem most suitable for the assessment of the reaction intensity in the ENG. At present, the examination with Frenzel's glasses represents the best possibility for differentiation between physiological and pathological spontaneous nystagmus.