Objective: Patients with Parkinson’s disease (PD) are significantly disturbed in their daily life when accompanied by the PISA syndrome (PS) of lateral bending.

Background: We investigated the visual cognition involved in postural maintenance in patients with PD and PS based on the Romberg ratio (body sway with eyes closed/open) being less than 1.0 upon stabilometric assessment. As new visual stimuli are transmitted to the visual cortex and further information is acquired by moving the line of sight (in microsaccades), this gaze movement was predicted to be impaired in PD, causing visual cognitive impairment.

Method: The following tests were reviewed for 2 years and statistically analyzed: gaze analysis and pupil diameter (Tobii prospectrum 1200), stabilizing test (Gravicorder GS-31), neuropsychological tests (MMSE, MOCA-J, CDT, WAIS-III building block problem, line orientation, dot counting, position discrimination, and cube analysis), and cerebral perfusion scintigraphy (¹²³I-IMP SPECT). A significantly decreased blood flow of IMP was defined by a Z score of 2.5 or more.

Results: Initially, 30 patients with PD and without dementia (MMSE score ≥24) not having PS were allotted in the PISA- group, while 20 patients with PD, without dementia and with PS, were assigned in the PISA+ group; there were no significant differences in age and sex between the groups. After 2 years of observation, we divided the patients into three groups: the PISA++ group, in which the patients had signs of PS at enrollment; the PISA-+ group, with patients of the PISA- group developing signs of PISA syndrome during the 2-year study period; and the PISA – – group, wherein patients of the PISA- group did not develop PS throughout the period. The PISA-+ groups showed significantly lower MMSE, position discrimination score, WAIS-III block problem, daily levodopa dose (p < 0.05), and blood flow in the left supramarginal and orbital gyri than the PISA– group. The PISA++ groups showed significantly lower MMSE, Romberg’s ratio of area, amplitude, velocity of microsaccades (p < 0.05), and blood flow in the left precuneus, superior temporal gyrus, and cuneus than the PISA-+ group.

Conclusion: Before the onset of PISA, there was a decreased blood flow in the correlative visual cortex and impairment of spatial cognition. In addition, the patients with PS had reduced saccades and slow microsaccades.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-crucial-role-of-the-visual-system-on-the-pisa-syndrome-in-parkinsons-disease/