Objective: To describe the programming criteria and patient characteristics for use of directional versus omnidirectional configurations for deep brain stimulation (DBS) in patients with Essential Tremor (ET).

Background: The mainstay of treatment for pharmacologically refractory ET has been DBS of the ventral intermediate (VIM) nucleus of the thalamus. Traditionally, programming parameters were limited to omnidirectional monopolar or bipolar configurations to achieve tremor suppression. However, the advent of segmented leads has expanded the armamentarium to include directional settings which provide a more refined target of stimulation which allows for optimization of tremor control and/or avoidance of off-target effects.

Method: We performed a retrospective chart review of patients currently followed within the OHSU DBS Clinic between February 2017 and September 2019 who met clinical criteria for medically refractory ET that underwent subsequent bilateral VIM DBS implantation with St. Jude Abbott segmented leads. Inclusion criteria required all 30 and 90 day programming visits to be completed at OHSU. Key characteristics were obtained including age at time of DBS, gender, use of directional versus omnidirectional at initial programming, reason for selecting directional, and follow up settings at 90 days.

Results: 33 patients (14 females) met inclusion criteria for Bilateral VIM DBS placement with segmented leads. Mean age at time of DBS implantation was 68 years old. At 30-day visit, directional configurations were used bilaterally in 11/33 and unilaterally for 6/33 conferring a 33.3% and 16.8% usage rate respectively. At 90 day follow up, 11/16 that were in omnidirectional had been changed to directional. Reasons for use of directional configuration during initial programming included avoiding stimulation related adverse effect such as paresthesia (5/17), or muscle contraction (9/17) or improved tremor control (3/17).

Conclusion: The ability to refine the field of activation allows programmers to limit current spread causing intolerable off target effects such as paresthesias, muscle contractions, or ataxia. Furthermore, the use of directional stimulation also allowed for greater tremor control at subsequent follow up visits. In our experience over 50% of patients receiving directional leads found clinical advantage in them over omnidirectional leads.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-role-of-directional-configuration-for-essential-tremor-a-single-center-experience/