In this paper, the authors' aim was to examine reasons underpinning decisions to undergo, or alternatively forgo, a second-sided deep brain stimulation (DBS) implantation in patients with Parkinson disease (PD).
Fifty-two patients with Parkinson disease (PD) were randomized to receive DBS to the subthalamic nucleus or globus pallidus internus (GPi) as part of the COMPARE trial. Forty-four patients had complete data sets. All patients were offered a choice at 6 months after unilateral implantation whether to receive a contralateral DBS implant. All patients had advanced PD. The mean patient age was 59.8 years (range 43–76 years), and the mean duration of disease was 12.2 years (range 5–21 years). The mean baseline Unified Parkinson's Disease Rating Scale (UPDRS)–III motor score was 42.7. The main outcome measures used in this study were the UPDRS-III Motor Scale and the UPDRS-IV Dyskinesia Scale.
Twenty-one (48%) of the 44 patients in the cohort did not undergo bilateral implantation and have been successfully treated for an average of 3.5 years; of these, 14 (67%) had a GPi target. The most common reason for adding a second side was inadequacy to address motor symptoms. Patient satisfaction with motor outcomes after unilateral DBS implantation was the most common reason for not undergoing bilateral implantation. Those who chose a second DBS procedure had significantly higher baseline UPDRS-III motor and ipsilateral UPDRS-III scores, and a significantly lower asymmetrical index. The logistic regression analysis revealed that the odds of proceeding to bilateral DBS was 5.2 times higher for STN than for GPi DBS. For every 1% increase in asymmetry, the odds of bilateral DBS decreased by 0.96.
Unilateral DBS is an effective treatment for a subset of patients with PD. Baseline asymmetry is an important factor in the effectiveness and decision-making process between unilateral and bilateral DBS. Patients with GPi DBS in this cohort were more likely to choose to remain with unilateral implantation.
Abbreviations used in this paper: DBS = deep brain stimulation; GPi = globus pallidus internus; PD = Parkinson disease; STN = subthalamic nucleus; UPDRS = Unified Parkinson's Disease Rating Motor Scale.
FunkiewiezAArdouinCCaputoEKrackPFraixVKlingerH: Long term effects of bilateral subthalamic nucleus stimulation on cognitive function, mood, and behaviour in Parkinson's disease. J Neurol Neurosurg Psychiatry75:834–8392004
OkunMSFernandezHHWuSSKirsch-DarrowLBowersDBovaF: Cognition and mood in Parkinson's disease in subthalamic nucleus versus globus pallidus interna deep brain stimulation: the COMPARE trial. Ann Neurol65:586–5952009
ZahodneLBOkunMSFooteKDFernandezHHRodriguezRLWuSS: Greater improvement in quality of life following unilateral deep brain stimulation surgery in the globus pallidus as compared to the subthalamic nucleus. J Neurol256:1321–13292009