Directional Leads for Deep Brain Stimulation: Technical Notes and Experiences

Abstract

<b><i>Objective:</i></b> Deep brain stimulation (DBS) is an approved treatment for movement disorders. Despite high precision in electrode placement, side effects do occur by current spread to adjacent fibers or nuclei. Directional leads (D-leads) are designed to adapt the volume of stimulation relative to the position within the target by horizontal and vertical current steering directions. The feasibility of implanting these new leads, possible difficulties, and complications were the focus of this study. <b><i>Material and Methods:</i></b> This analysis is based on 31 patients who underwent a DBS procedure with D-leads and an implantable pulse generator (IPG) capable of multiple independent current control and 31 patients who received non-D-leads with a similar IPG. While trajectory planning and most steps of the surgical procedure were identical to conventional DBS lead implantation, differences in indication, electrode handling, lead control, and complications were documented and analyzed in comparison to a control group with ring electrodes. <b><i>Results:</i></b> During a consecutive series of 51 patients implanted with a DBS system, 31 patients (60.1%) were selected for implantation of D-leads and received 59 D-leads, 28 bilateral, and 3 unilateral implantations. The control group consisted of a consecutive series of a comparable time period, with 31 patients who received conventional ring electrodes. Indication of D-lead implantation was based on the anatomic conditions of the trajectory and target regions and the results of intraoperative test stimulations. In 1 patient, primary D-lead implantation on both sides was performed without any microelectrode implantation to minimize risk for hemorrhage. In the absence of an externally visible marker, the control of implant depth and of the orientation of the D-lead needs to be controlled by X-ray resulting in a longer fluoroscopy time and, therefore, higher X-ray dose compared to conventional lead implantations (415.53 vs. 328.96 Gy cm<sup>2</sup>; <i>p</i> = 0.09). Mean procedure duration for complete system implantation did not differ between either type of leads (ring electrodes vs. D-leads, 08:55 vs. 09:02 h:min). Surgical complications were unrelated to the type of electrode: surgical revision was necessary and successfully performed in 1 subcutaneous hematoma and 1 unilateral electrode dislocation. A rather rare complication, symptomatic idiopathic delayed-onset edema, was observed in 4 patients with D-leads. They recovered completely within 1–3 weeks, spontaneously or after short-term cortisone medication. In the control group, in a series of 31 patients (20 implanted with Medtronic 3389 lead and 11 with Boston Scientific Vercise lead), not a single problem of this kind was encountered at any time. <b><i>Conclusion:</i></b> Precise positioning of D-leads is more challenging than that of conventional DBS leads. By adding an external lead marker, control of optimal lead position and orientation is enhanced. In case of supposed increased risk for hemorrhage because of vessels crossing all possible trajectories in the pre-surgical navigated simulation program, primary D-lead implantation instead of the sharper microelectrodes may be a feasible alternative and it may offer more options than ring electrodes especially in these cases. Prospective studies comparing ring-mode stimulation to directional stimulation to examine the differences of the clinical effects have been started.

Real-Life Experience on Directional Deep Brain Stimulation in Patients with Advanced Parkinson’s Disease

“…dDBS has not presented greater risk in DBS lead implantation [ 35 ]. In a two-year retrospective analysis of Medicare and Medicaid Services, it was noted that patients with dDBS systems were 36% less likely to undergo re-operation than patients with the traditional DBS system [ 36 ].…”

Which one is the superior target? A comparison and pooled analysis between posterior subthalamic area and ventral intermediate nucleus deep brain stimulation for essential tremor

“…While conventional DBS electrode contacts stimulate the ring‐shaped area around the electrode, directional electrodes achieve stimulation in different directions by dividing the ring electrode into segmented electrodes. Based on these clinical characteristics, including local field potential (LFP), a larger treatment window and more precise stimulation can be achieved 77,78 …”

“…Based on these clinical characteristics, including local field potential (LFP), a larger treatment window and more precise stimulation can be achieved. 77 , 78 …”

Surgical Strategy for Directional Deep Brain Stimulation

“…3A ). 26 , 29) With a D-lead, some authors proposed that directional segments (2, 3) should be placed in sweet spots, 23 , 30) as decided from microelectrode recording (MER) and test stimulation, but no specific indicators were shown. In our hospital, 4 was often the optimal stimulation site in the conventional arrangement in STN-DBS and Vim-DBS, so we have changed the arrangement so that 2 and 3 in the part where the kinesthetic response and tremor rhythm are recorded by MER.…”

“…Steigerwald et al and Fricke et al therefore noted that the measurement of the TW with OS should be tried as a first step, focusing the monopolar review on the DS at the level of the best TW on OS. 23 , 29 , 30) The Informity tool for monopolar review is available from Abbott. Informity works with a user-friendly interface on an iPad (Apple), and users can easily switch between each contact alone, combinations of two contacts, and OS using all three contacts, gradually increasing the stimulus, and recording amplitude and symptoms with effects and side effects ( Fig.…”