Vestibular evoked myogenic potentials in patients with spinocerebellar degeneration.

To estimate vestibulo-collic reflexes in patients with spinocerebellar degeneration (SCD), vestibular evoked myogenic potentials (VEMPs) were recorded in 16 patients with SCD and in 9 normal subjects. The patients with SCD were classified into three groups: those with olivo-ponto-cerebellar ataxia (OPCA; n = 10); those with cortical cerebellar atrophy (CCA; n = 3); and those with Machado-Joseph disease (MJD; n = 3). While all of the patients with OPCA and CCA showed biphasic responses (p13-n23), 2 of the 3 patients with MJD showed abnormal VEMPs bilaterally. Three sides in these 2 patients showed an absence of VEMPs, and one side showed a remarkably delayed p13. These two patients showed little response in caloric tests. These results suggest that the vestibulo-collic reflex as well as the vestibulo-ocular reflex could be damaged in MJD patients but preserved in OPCA and CCA patients.