Abstract Details

Title Bipolar Versus Monopolar Electrode Configuration in Thalamic DBS for Essential Tremor

Topic Movement Disorders

Presentation(s) P05 - (-)

Poster/Presentation
Number 033

Objective

Background BACKGROUND: DBS of the thalamic ventral intermediate nucleus (VIM) is an effective therapy for severe essential tremor (ET) poorly responsive to medications. While DBS efficacy is well documented, optimal stimulation parameters are not well established.

Design/Methods DESIGN/METHODS: Case series from chart review in an academic movement disorders program.

Results RESULTS: 10 ET patients received unilateral or bilateral VIM DBS. All were initially programmed using monopolar stimulation, with active DBS contact(s) configured as cathode and IPG as anode, but were eventually switched to bipolar configuration with anode referred to an adjacent contact on the electrode. Bipolar settings demonstrated equivalent or better tremor control than monopolar, as determined by physical exam, handwriting samples and spiral drawing. Paresthesias, particularly on morning device activation, improved in 6 patients, dysarthria in 3 patients, balance difficulties in 3 patients and contralateral tetany in 2 patients. One patient reported dysgeusia, which has not resolved despite configuration changes. Mean voltage and impedance values for bipolar settings were higher (monopolar: 2.5 volts (SD 0.7), 1308 [Omega] (SD 231) vs bipolar: 3.4 volts (1.8), 2037 [Omega] (565)). However, current was comparable (2.2 mA (1.5) bipolar vs. 2.1 mA (0.85) monopolar).

Conclusions CONCLUSIONS: Thalamic DBS is effective in controlling medically intractable ET, but adverse effects may complicate therapeutic stimulation. Bipolar stimulation appears to improve or resolve many of the symptoms associated with monopolar configuration(s), while achieving equal or better tremor control. We propose to adopt bipolar configurations during initial device programming in ET patients treated with VIM DBS and not just as a rescue technique. Further analysis is needed to compare the clinical and physiological effects of monopolar and bipolar stimulation.

Authors/Disclosures
Tyler Cheung, MD (Southern California Neurology Associates) PRESENTER	No disclosure on file
	No disclosure on file
Michele Tagliati, MD, FAAN (Cedars-Sinai Medical Center)	Dr. Tagliati has received publishing royalties from a publication relating to health care.
Olga Ciccarelli, MD, PhD, FRCP (UCL Institute of Neurology)	Prof. Ciccarelli has received personal compensation in the range of $0-$499 for serving as a Consultant for Lundebeck. Prof. Ciccarelli has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Prof. Ciccarelli has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Prof. Ciccarelli has received personal compensation in the range of $0-$499 for serving on a Speakers Bureau for Merck. Prof. Ciccarelli has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for NEUROLOGY Journal.

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