Abstract
ObjectiveTo investigate the effects of subthalamic nucleus (STN) and globus pallidus internus (GPi), deep brain stimulation (DBS) on individual action tremor/postural tremor (AT) and rest tremor (RT) in Parkinson’s disease (PD). Randomized DBS studies have reported marked benefit in tremor with both GPi and STN and DBS, however, there is a paucity of information available on AT vs RT when separated by the surgical target.MethodsWe retrospectively reviewed the 1-year clinical outcome of PD patients treated with STN and GPi DBS at the University of Florida. We specifically selected patients with moderate to severe AT. Eighty-eight patients (57 STN and 31 GPi) were evaluated at 6 and 12 months for changes in AT and RT in the OFF-medication/ON stimulation state. A comparison of “response” was performed and defined as greater than or equal to a 2-point decrease in tremor score.ResultsSTN and GPi DBS both improved AT at 6- and 12-months post-implantation (p < 0.001 and p < 0.001). The STN DBS group experienced a greater improvement in AT at 6 months compared to the GPi group (p = 0.005) but not at the 12 months follow-up (p = 0.301). Both STN and GPi DBS also improved RT at 6- and 12-months post-implantation (p < 0.001 and p < 0.001). There was no difference in RT scores between the two groups at 6 months (p = 0.23) or 12 months (p = 0.74). The STN group had a larger proportion of patients who achieved a “response” in AT at 6 months (p < 0.01), however, this finding was not present at 12 months (p = 0.23). A sub-analysis revealed that in RT, the STN group had a larger percentage of “responders” when followed through 12 months (p < 0.01).ConclusionBoth STN and GPi DBS reduced PD associated AT and RT at 12 months follow-up. There was no advantage of either brain target in the management of RT or AT. One nuance of the study was that STN DBS was more effective in suppressing AT in the early postoperative period, however, this effect diminished over time. Clinicians should be aware that it may take longer to achieve a similar tremor outcome when utilizing the GPi target.
Highlights
The cardinal motor features of Parkinson’s disease (PD) include resting tremor, bradykinesia, rigidity and postural instability
We evaluated the longitudinal tremor outcomes in PD patients with moderate to severe action tremor (AT) managed with either subthalamic nucleus (STN) or globus pallidus internus (GPi) Deep brain stimulation (DBS)
The inclusion criteria for the study comprised the following (1) Diagnosis of PD was established with United Kingdom PD Society Brain Bank Criteria (Hughes et al, 1992) (2) Patients had moderate to severe AT before surgery corresponding to a score of ≥2 on item 21 the Unified Parkinson’s Disease Rating Scale (UPDRS) part III. (3) Unilateral or bilateral DBS of either STN or GPi nucleus
Summary
The cardinal motor features of Parkinson’s disease (PD) include resting tremor, bradykinesia, rigidity and postural instability. Deep brain stimulation (DBS) is an established therapy for the treatment of motor symptoms in PD and has been shown to be more effective than best medical therapy in improving motor function and quality of life in well-selected PD patients (Weaver, 2009). Several studies have compared the effects of these targets on the combined control of RT and AT (DBS for PD Study Group, 2001; Anderson et al, 2005; Weaver et al, 2012; Odekerken et al, 2013). A recent retrospective study found equivalent tremor outcomes, DBS targets for comparisons involved STN and the ventral intermedius nucleus (VIM) but not the GPi (Parihar et al, 2015). We evaluated the longitudinal tremor outcomes in PD patients with moderate to severe AT managed with either STN or GPi DBS. We investigated whether pre-surgical or other factors could affect AT tremor outcome
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