Clinical significance of visual fixation upon caloric nystagmus-caloric pattern test- (author's transl)

Abstract

The effect of opening of the eyes and of ocular fixation upon caloric nystagmus has been routinely tested in our neurotological assessment of patients since 1974. All cases who showed a sign of FFS (Failure of Fixation-Suppression of Caloric Nystagmus) were found to have central nervous 'system '.lesions, especially posterior fossa lesions. From an analysis of caloric nystagmus with the sign of FFS, patterns of FFS were classified into the following three types. Type I Visual fixation failed to suppress caloric nystagmus to both directions. In this type, diffuse involvement of the central nervous system such as cerebellar degeneration, organic mercurials intoxication and myoclonus epilepsy was included. Type II : Visual suppression of caloric nystagmus could not be observed on either side regard-less of water temperature applied as caloric' stimuli. In this type, cerebellopontine angle syndrome such as acoustic tumor, meningioma, epidermoid and arachnoiditis was included. Type III: Visual fixation failed to suppress caloric nystagmus to either direction depending upon caloric stimuli. In this type, vascular disorder, head trauma and unilaterally located tumor of the cerebellar hemisphere were included. On the basis of our clinical data classified above, underlying neuroanatomical mechanism was discussed.