Impaired suppression of vestibular nystagmus by fixation of visual and acoustic targets in neurological patients.

Suppression of vestibular nystagmus induced by fixation of visual and acoustic
targets moving with the head during sinusoidal rotation (0.1 Hz, 75
degrees/second peak velocity) was tested in cerebellar and noncerebellar
patients. Visual suppression was impaired greatly in cerebellar patients, without
correlation with visual smooth-pursuit defects. Acoustic suppression was equal to
or slightly weaker than visual suppression. In noncerebellar patients, a
disturbance of visual suppression was found only in the presence of a severe
impairment of pursuit eye movements. Acoustic suppression did not parallel the
visual-suppression pattern. In clinical vestibular examination, an impaired
modulation of the vestibulo-ocular reflex suggests a cerebellar dysfunction, but
also can occur in the presence of disorders of other parts of the CNS severely
affecting the SP system.