gms | German Medical Science

Objective: Deep brain stimulation is mainly used for treatment of movement disorders with target points in the STN, the VIM or the GPI. Despite a high precision of electrode placement in the target area side effects can occur by stimulating adjacent fibers or nuclei. There are different types of deep brain stimulation electrodes, which until 2015 all had circular electrode poles in a row, e.g. Vercise lead (Boston scientific) with eight poles or 3389-lead (Medtronic) with four poles. Since 9/2015 the first directional lead (Cartesia, Boston scientific) is available. It contains four circular electrode poles in a row, whereof the two central ones are segmented in respectively three poles, which individually can be controlled. Thereby a more precise adjustment of the applied electric field compared to the circular poles is possible.

Methods: 28 patients underwent a bilateral implantation of Cartesia directional leads, three patients a unilateral implantation. Four of these cases were revision operations with a new placement of the electrodes. Nine of the patients were female, 23 male (ø59,9 years). In 27 cases the patients had a Parkinson’s disease, three patients had a tremor, and one patient had dystonia. Also the intraoperative test stimulation was unchanged. The application of a directional electric field via the test electrodes was not possible. Depending on the effects and the side-effects of the test-stimulation and especially on the stimulation-range between these it was decided, if a directional lead was necessary or if a standard electrode with circular poles would be. The implantation of the directional lead was controlled by x-ray. In contrast to standard electrodes not only the precision along the planned trajectory was important, also the rotation of the lead had to be controlled. Different to the standard electrodes the two segmented circular poles of the directional lead should lie in the area of the target point. The deeper one begins 3,1mm from the tip of the electrode. Consequently these electrodes have to be implanted more ventral than the standard ones to use their unique effect.

Results: In three cases complications occurred, which were no consequences of the used type of electrode and did not differ from the usual complications that could occur. A not significant higher x-ray-dose was needed for the placement of the directional lead compared to Vercise- or 3389-leads (415,53 vs. 328,96 Gycm²; p=0,09). The mean duration of the implantation was nearly the same (08:59 vs. 08:55 h:min).

Conclusion: From a surgeons point of view the exact implantation of the directional leads is slightly more challenging, but of course feasible. The higher x-ray-dose is surely acceptable. The first impression of the improved clinical effects seems optimistic. Prospective studies to compare ring-mode-stimulation with directional-stimulation are needed and are already in process.