Factors affecting postural instability after more than one-year bilateral subthalamic stimulation in Parkinson's disease: A cross-sectional study.

Andrea Kelemen,Dávid Kis,Péter Klivényi,Bence Laczó,Dániel Bereczki,Muthuraman Muthuraman,Dénes Zádori,Gertrúd Tamás,László Halász,Gábor Fekete,Gábor Rudas,Loránd Erőss,László Bognár

doi:10.1371/journal.pone.0264114

Abstract

BackgroundBalance impairment in Parkinson’s disease is multifactorial and its changes due to subthalamic stimulation vary in different studies.ObjectiveWe aimed to analyze the combination of predictive clinical factors of balance impairment in patients with Parkinson’s disease treated with bilateral subthalamic stimulation for at least one year.MethodsWe recruited 24 patients with Parkinson’s disease treated with bilateral subthalamic stimulation and 24 healthy controls. They wore an Opal monitor (APDM Inc.) consisting of three-dimensional gyroscopes and accelerometers in the lumbar region. We investigated four stimulation conditions (bilateral stimulation OFF, bilateral stimulation ON, and unilateral right- and left-sided stimulation ON) with four tests: stance on a plain ground with eyes open and closed, stance on a foam platform with eyes open and closed. Age, disease duration, the time elapsed after implantation, levodopa, and stimulation responsiveness were analyzed. The distance of stimulation location from the subthalamic motor center was calculated individually in each plane of the three dimensions. We analyzed the sway values in the four stimulation conditions in the patient group and compared them with the control values. We explored factor combinations (with age as confounder) in the patient group predictive for imbalance with cluster analysis and a machine‐learning‐based multiple regression method.ResultsSway combined from the four tasks did not differ in the patients and controls on a group level. The combination of the disease duration, the preoperative levodopa responsiveness, and the stimulation responsiveness predicted individual stimulation-induced static imbalance. The more affected patients had more severe motor symptoms; primarily, the proprioceptive followed by visual sensory feedback loss provoked imbalance in them when switching on the stimulation.ConclusionsThe duration of the disease, the severity of motor symptoms, the levodopa responsiveness, and additional sensory deficits should be carefully considered during preoperative evaluation to predict subthalamic stimulation-induced imbalance in Parkinson’s disease.

Highlights

The long-term effects of subthalamic stimulation (STN DBS) on postural instability in Parkinson’s disease (PD) still need exploration.In PD, different elements of balance control are abnormal, and their interaction disposes patients towards falls [1]
The more affected patients had more severe motor symptoms; primarily, the proprioceptive followed by visual sensory feedback loss provoked imbalance in them when switching on the stimulation
The duration of the disease, the severity of motor symptoms, the levodopa responsiveness, and additional sensory deficits should be carefully considered during preoperative evaluation to predict subthalamic stimulation-induced imbalance in Parkinson’s disease

Summary

Introduction

The long-term effects of subthalamic stimulation (STN DBS) on postural instability in Parkinson’s disease (PD) still need exploration.In PD, different elements of balance control (balance during quiet stance, the reactive postural adjustments to external perturbations, the anticipatory postural adjustment in preparation for voluntary movements, and the dynamic balance during movements) are abnormal, and their interaction disposes patients towards falls [1]. The long-term effects of subthalamic stimulation (STN DBS) on postural instability in Parkinson’s disease (PD) still need exploration. Balance impairments were documented already in the prodromal [2] and the early stage of Parkinson’s disease [3] and increased with disease progression [4], along with the neurodegeneration in dopaminergic and non-dopaminergic networks [5,6]. They contribute to disability [7] and falls [8]. Subthalamic stimulation has a beneficial effect on postural instability in the first 9–12 months of the therapy, which wanes over time [18–21] as a result of a possible neuromodulatory effect [21] or as a result of the disease progression [18]. Balance impairment in Parkinson’s disease is multifactorial and its changes due to subthalamic stimulation vary in different studies

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Results

Conclusion