Impaired modulation of the otolithic function in acute unilateral cerebellar infarction.

To define the cerebellar contribution in modulating the otolithic signals, we investigated the otolithic function in 27 patients with acute unilateral cerebellar infarctions in the territory of the posterior inferior cerebellar artery (PICA, n = 17, 63%), combined PICA and superior cerebellar artery (SCA) (n = 7, 30%), SCA (n = 2, 7%), and anterior inferior cerebellar artery (n = 1, 4%) from 2010 to 2012. The patients had evaluation of the ocular tilt reaction [head tilt, ocular torsion (OT), and skew deviation], tilt of the subjective visual vertical (SVV), cervical vestibular evoked myogenic potentials (VEMPs) in response to air conducted tone bursts, and ocular VEMPs induced by tapping the head at AFz. The evaluation was completed within 2 weeks after symptom onset. Patients often showed OT or SVV tilt (15/27, 55.6%) that was either ipsi- (n = 6) or contraversive (n = 9). Overall, there were no differences in the amplitudes and latencies of cervical and ocular VEMPs between the ipsi- and contralesional sides. However, individual analyses revealed frequent abnormalities of cervical (11/27, 41%) and/or ocular (9/27, 33%) VEMPs. While 11 (73%) of the 15 patients with the OTR/SVV tilt showed abnormalities of cervical (n = 9) and/or ocular (n = 7) VEMP responses, only three (25%) of the 12 patients without the OTR/SVV tilt had abnormal cervical (n = 2) and/or ocular (n = 2) VEMPs (73% vs. 25%, Fisher's exact test, p = 0.021). The concordance rate in the results of cervical and ocular VEMPs was marginally significant (19/27, 70%, p = 0.052, binominal). Unilateral cerebellar lesions may generate otolithic imbalances, as evidenced by the OTR/SVV tilt and asymmetric ocular or cervical VEMP responses, but without directionality according to the lesion side. Patients with the OTR/SVV tilt had abnormal VEMPs more often than those without.