Objective: To identify the changes of subjective visual vertical and any correlation between SVV and cognitive/motoric dysfunctions in Parkinson’s disease.

Background: Dysfunction of sensory system is another well-known manifestation in Parkinson’s disease (PD). Among various sensory dysfunctions reported in PD, multisensory orientation perceptions such as the subjective visual vertical (SVV) has been relatively less studied until now. Since PD patients is postulated to be more visual dependent than controls, increased visual dependence was suggested in PD patients. However, perception of the relative orientation of the self and objects in the environment requires integration of not only visual but also vestibular information. Accordingly, another study reported that PD patients was not more visually dependent in general and they might rely more on vestibular information depending on tasks while taking dopaminergic medications. Recent studies suggest that there are close relationships between cognitive dysfunction, abnormal vertical perception and postural instability. 

Methods: Ten PD patients and five healthy controls were included in this study. We exclude any subject who had visual or auditory symptom or sign in the age- and sex-matched control group as well as the patient group. The static SVV was assessed in a seated upright position using automated software program to measure the deviations of the luminous line in relation to the gravity’s vertical axis. Korean Mini-Mental status examinations were also administered in patients and controls. Subjects with PD were evaluated using the Unified Parkinson’s Disease Rating Scale.

Results: In patients group, seven woman and three man were included and their Hoehn and Yahr stage was 1 or 2. There was no difference of the frequency or the deviation degree on the SVV abnormality between the control and the patient group. In both patient and control groups, mean K-MMSE scores were even as 28, and there was no significant correlation between cognitive score and the deviation degree of the SVV. However, there was some trend of positive correlation between the motoric dysfunction and the deviation degree of the SVV.

Conclusions: These findings suggest that impaired SVV is not evident in early PD patients, however, it might be a biomarker for disease progression. Motor dysfunction rather than cognitive dysfunction is related to the SVV impairment. 

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MDS Abstracts - https://www.mdsabstracts.org/abstract/subjective-visual-vertical-in-patients-with-early-parkinsons-disease/