Computer analysis of fixation-suppression of caloric nystagmus.

Effects of the ocular fixation upon caloric nystagmus were quantitatively analyzed and compared between normal subjects and patients by using a PDP 11/40 computer. The slow-phase velocity was the best parameter to separate normal from abnormal visual fixation. An analysis of caloric nystagmus with failure of fixation-suppression (FFS) made it possible to classify patterns of FFS into three types. The combination of FFS with impairment of the optokinetic responses provides a useful diagnostic tool with respect to lesions located between the brain stem and the cerebellum.