Abstract

Background
Otolith dysfunction including ocular tilt reaction and subjective visual vertical (SVV) tilts has been numerously reported in patients with unilateral peripheral vestibular or brainstem lesions. There have been few case reports of otolith dysfunction associated with posterior inferior cerebellar artery (PICA) territory cerebellar infarction. Objectives: To investigate the characteristic pattern of the otolith dysfunction in PICA territory cerebellar infarctions.
Methods
From March to October 2006, 15 consecutive patients with infarctions of PICA territory diagnosed by brain MRI were registered. SVV tilts, fundus photography, and prism cover tests were performed to evaluate the otolith function. Standard vestibular testing using three-dimensional video-guided oculography was also performed.
Results
Nine of 15 patients showed ipsilesional tilts of SVV (mean 3.6° at binocular vision), all (n=9) of whom had lesions in unilateral or bilateral hemisphere and/or vermis, but none of patients showed lesion in the nodulus. Among 9 patients with ipsilesional SVV tilts, 5 also showed body lateropulsion to the lesion side on brain MRI and 3 showed ipsilesional spontaneous nystagmus (SN). All except one had normal range of ocular torsion (OT). Three of 15 patients showed contralesional tilts of SVV (mean 10.5° at binocular vision), all of whom had lesion in the nodulus. One patient with pure nodular lesion showed body lateropulsion to contralesional side. All (n=3) patients with contralesional SVV tilts also showed pathological conjugate OT to the contralesional side and 2 of them showed contralesional skew deviation. They had SN beating toward to the side of the lesion. The others 3 showed no pathological SVV tiltS, body lateropulsion, or pathological OT.
Conclusion
Two different patterns of SVV tilts and body lateropulsion can occur in PICA territory cerebellar infarction. Ipsilesional SVV tilts without accompanying OT in non-nodular cerebellar lesion may imply that SVV tilting is not dependent to OT in patients with PICA territory non-nodular cerebellar infarction.