Objective: The feasibility of applying new directional leads (D-leads) in standard DBS procedures, possible difficulties or complications were the focus of this study.

Background: DBS is mainly used for treatment of movement disorders. Despite high precision in electrode placement, side effects can occur by stimulating adjacent fibers or nuclei by the volume of tissue activated (VTA). Leads with smaller electrode contacts by horizontal segmentation into three contacts instead of one ring contact are designed to apply and to direct smaller stimulation volumes.

Methods: 31 patients (23 male, Ø age 59,9, 27 PD, 1 dystonia, 3 tremor, 3 unilateral) underwent a DBS procedure with 59 segmented leads (Cartesia, Boston Scientific). Stereotactic planning, micro-electrode recording and testing were identical to the previous procedure. The decision for directional leads was made intraoperatively, if test stimulation through the microelectrodes indicated a narrow therapeutic window. Fluoroscopy was used to control implantation of the definite DBS lead. In contrast to standard electrodes not only the depth and possible sagittal deviation from the planned trajectory was important, but also the rotation of the electrode, which was controlled by alignment of a X-ray marker above the electrode level. For placing the two middle contacts with D-lead components at the spot of best response, the lowest tip was planned to be placed about 3 mm deeper.

Results: In three cases complications occurred (1 subcutaneous hematoma, 1 electrode dislocation, 1 brain edema) which did not differ from the well-known complications of DBS lead implantation. A slightly longer fluoroscopy time was needed for the placement of the directional lead compared to conventional leads (415,53 vs. 328,96 Gycm²; p=0,09). Mean duration of surgery did not differ between procedures with implantation of a conventional and a segmented DBS lead  (08:59 vs. 08:55 h:min). ). In early follow-up, in most patients at least unilateral D-lead segment has been activated for chronic stimulation. 

Conclusions: From a surgeon’s point of view, the exact implantation of the directional leads in a correct horizontal mode is slightly more challenging than a conventional DBS lead, but feasible. The higher x-ray-dose is minimal and surely acceptable in view of the estimated long-term advantage. Prospective studies to compare ring-mode-stimulation with directional-stimulation are needed and are already in process.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/first-experience-with-59-directional-leads-in-deep-brain-stimulation/