Comparison of STN and GPi DBS in patients with Parkinson’s disease and substantial Action/Postural Tremor

Congratulations to Drs. Kamilia Nozile-FirthVyas ViswanathanAdolfo Ramirez ZamoraKelly FooteMichael Okun and Aparna Wagle-Shukla on the publication of “Comparison of STN and GPi DBS in patients with Parkinson’s disease and substantial Action/Postural Tremor.”


Objective: Determine the effects of deep brain stimulation (DBS) on action/postural tremor (AT) control in patients with Parkinson’s disease (PD) and identify any specific target associations.

Background: DBS is an effective therapy for the control of PD tremor. Subthalamic nucleus (STN) and globus pallidus internus (GPi) are frequent DBS targets, however there is no consensus regarding the relative efficacy of AT suppression between these targets. Previous research focuses on the effects of DBS on rest tremor (RT). The effect of neuromodulation on AT has not been determined, even though AT affects 40 – 50% of PD patients and contributes significantly to functional disability.

Design/Methods: We retrospectively identified PD DBS patients who presented with moderate-to severe AT in their dominant hand. Patients scoring ≥ 2 on item 21 (for AT, item scored 0–4) of the Unified PD Rating Scale part III were included. Tremor assessments were performed before surgery (off medication), six months, and one year after surgery (off medication – on stimulation).

Results: Eighty-eight patients (57 STN, 31 GPi, mean age 61 ± 9.7, 68 males, 20 females) were retrospectively analyzed. GPi and STN groups were similar in age (p = 0.6), gender (p = 0.3) and baseline AT score (STN 2.4 ± 0.9; GPi 2.3 ± 0.9; p= 0.52). AT decreased with STN (1.7 points, 73%, p<0.001) and GPi stimulation (1.2 points, 52%; p<0.001). The odds of AT decreasing by ≥2 points favored STN (OR 3.78; p = 0.004) at six months however at one year, AT improvement was equivalent between the targets (p= 0.22). Increased age at surgery negatively impacted the odds of ≥ 2 points improvement.

Conclusions: Action tremor in PD was effectively controlled by DBS in both STN and GPi targets. Prospective studies on tremor outcomes are needed for direct comparison.