Unilateral Versus Bilateral Ventral Intermediate Nucleus Deep Brain Stimulation for Axial Tremor

Objective: To evaluate effects of unilateral ventral intermediate nucleus (VIM) thalamic deep brain stimulation (DBS) on axial tremor in Essential Tremor (ET). Additionally, we compared the efficacy and tolerability of unilateral versus bilateral stimulation. Background: Many DBS experts assume that bilateral DBS is necessary for improvement in axial tremor in ET, but with incremental risk for surgical adverse events including speech and gait impairment. In this post hoc analysis from the largest controlled trial to date evaluating the St Jude non-directional lead constant current DBS device for ET (Wharen et al., Parkinsonism Relat Disord, 2017), we sought to either confirm or refute this notion and to better understand the effects of unilateral stimulation on axial tremor. Design/Methods: Two cohorts were analyzed: patients with unilateral implants (n=119) and those with unilateral implants who underwent a staged second sided implant after six months (n=39). Outcomes included change in Clinical Rating Scale for Tremor (CRST) axial subitems from baseline to 90 and 180 days as well as the on- and off-stimulation conditions at each timepoint and adverse effects. A within subject comparison of the staged cohort of unilateral versus bilateral DBS at 180 days was also performed. Results: Unilateral stimulation improved head(p Conclusions: Unilateral VIM stimulation for severe ET significantly improved axial ET symptoms, and bilateral stimulation was associated with additional adverse effects. If individual patient expectation is to improve contralateral arm tremor and axial tremor, then unilateral stimulation may be sufficient and could avoid unnecessary morbidity. Study Supported by: Abbott (formerly St Jude medical) Disclosure: Dr. Mitchell has nothing to disclose. Dr. Peichel has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Abbott. Dr. Peichel holds stock and/or stock options in Abbott. Dr. Wharen has nothing to disclose. Dr. Okun has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with National Parkinson Foundation, Medscape, Mededicus. Dr. Guthrie has nothing to disclose. Dr. Uitti has nothing to disclose. Dr. Larson has nothing to disclose. Dr. Walker has nothing to disclose. Dr. Pahwa has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Abbvie, ACADIA, Acorda, Adamas, Cynapses, Global Kinetics, Lundbeck, Neurocrine, Pfizer, Sage, Sunovion, Teva Neuroscience and US World Meds. Dr. Pahwa has received research support from Abbvie, Adamas, Avid, Biotie, Boston Scientific, Civitas, Cynapses, Kyowa, National Parkinson Foundation, NIH/NINDS, Parkinson Study Group. Dr. Dashtipour has nothing to disclose. Dr. Jankovic has nothing to disclose. Dr. Foote has nothing to disclose. Dr. Schwalb has nothing to disclose. Dr. Ford has nothing to disclose. Dr. Simpson has nothing to disclose. Dr. Phibbs has nothing to disclose. Dr. Neimat has nothing to disclose. Dr. Stewart has nothing to disclose. Dr. Marshall has nothing to disclose. Dr. Ostrem has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Neurocrine, Adamas.