Objective: The aim was to identify characteristic pre-surgical visual and vestibular disturbances, as well as neuroimaging changes that could be predictors of PI and gait disturbances.

Background: Рostural instability(PI) and gait disturbances are the most common clinical symptoms of advanced stages of Parkinson’s disease (PD). Despite the fact that subthalamic nucleus stimulation (STN-DBS) has a positive effect on motor symptoms, this surgery may provoke a more rapid balance and gait impairments in some patients. The DBS effect may depend on the specific neurophysiological and structural changes in the brain associated with PD. Since multisensory information such as visual and vestibular information is known to influence different areas of the brain, allowing for adaptive control of posture and gait.

Method: Participants included 28 PD patients and 30 age-matched controls. In addition to the cVEMP study reflecting the functioning of the vestibulospinal tract, we assessed mobility, balance and walking ability using the Timed Up and Go Test (TUG), Freezing of Gait Questionnaire (FOG-Q) before and after surgery. We also applied neuropsychological tests and MRI voxel-based morphometry. Threshold perimetry (TP) was used to quantify visual dysfunction across the visual fields.

Results: The characteristics of patients and controls are presented in Table 1. General information on changes in the studied parameters during the follow-up examination is presented in table 2. Within 3-5 years after STN-DBS, 10 patients developed moderate or severe PI. They initially showed worse visual field and cVEMP results, as well as a more pronounced reduction in the frontal cortex volume. A correlation was determined between the FOGQ score, TUG test performed after surgery and the cortical areas (before surgery) related to the dorsal and ventral visual information processing system (p˂0,03), as well as the frontal cortical areas (p˂0,02). TP and cVEMP parameters obtained before surgery also had a correlation with the FOGQ score (p˂0,02), the lingual gyrus (p˂0,03) orbitofrontal and prefrontal cortex (p˂0,01).

Conclusion: Preoperative assessment of vestibular and visual function, as well as cortical areas associated with the visual information processing system and frontal cortical areas responsible for planning and programming movements, helps to minimize the development of severe PI and gait disturbances after STN-DBS.

Table 1.

Table 2.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/predictors-of-%d1%80ostural-instability-and-gait-disturbances-after-stn-dbs-in-parkinsons-disease/