Long-Term Clinical Experience with Directional Deep Brain Stimulation Programming: A Retrospective Review.

Introduction: Directional deep brain stimulation (d-DBS) axially displaces the volume of tissue activated (VTA) towards the intended target and away from neighboring structures potentially improving benefit and reducing side effects (SE) of stimulation. A clinical trial evaluating d-DBS demonstrated a wider therapeutic window (TW) with directional electrodes. While this seems advantageous, it remains unclear when and why directional stimulation is chosen clinically. To evaluate the implementation of d-DBS in our practice we examined the prevalence of and motivation for directional programming.

Methods: A retrospective review was completed in consecutive patients with Parkinson's disease (PD)/essential tremor (ET) implanted with the Abbott Infinity system from December 2016 to January 2020. At 3, 12, 24, and 36 months we extracted post-DBS stimulation parameters; use of directional electrodes and other advanced programming techniques; and reasons for directional programming.

Results: Fifty-six patients with PD and 18 patients with ET (104 and 33 leads, respectively) were identified. The numbers of patients programmed with a directional electrode in at least one DBS lead in PD and ET, respectively, were 22/56 (39%) and 13/18 (72%) at 3 months; 19/48 (40%) and 8/12 (67%) at 12 months; 12/31 (39%) and 5/8 (63%) at 24 months; and 6/9 (67%) and 1/2 (50%) at 36 months. In PD and ET, reasons for using directional stimulation were better symptom control, less SE, or combination of better symptom control/SE; additional reasons in ET were improved battery/TW%.

Conclusion: Over a 36-month time period 39-68% of patients with PD and 50-72% of patients with ET had at least one lead programmed directionally in order to either improve symptom control or reduce side effects, an option not available with conventional omnidirectional stimulation. Initially directional electrodes were used in ET more frequently than PD, likely because of the less complex nature of programming for a monosymptomatic disorder. However, over time this shifted as we gained directional experience and sought solutions to reduce worsening symptoms.