Objective: To analyse the objective data and experiences in the application of directional leads (D-leads) in deep brain stimulation (DBS) for movement disorders.

Background: Recent reports indicate difficulties in positioning lead segments as exactly as planned (Reinacher et al. 2017, Hallerbach et al. 2018).

Method: From September 2015 to October 2018, 96 patients (mean age 59.9 years, 34 females) underwent a DBS procedure with segmented leads (D-leads), for Parkinson’s Disease in 71, dystonia in 11 and tremor in 14 patients. Data were prospectively collected and evaluated for the following parameters: intra-operative test results, reasons for D-lead, surgical handling, therapeutic window, configuration of electrode activation early and at a minimum follow-up of 3 months.

Results: At test stimulation in awake patients (PD and tremor), the best therapeutic effect was obtained at 1.5mA/ 1.7mA (left vs. right side). The intra-operative therapeutic window was 3.2mA (SD 1.4) on the left, 3.9mA (SD 2.1 mA) on the right; in single cases it was below 2mA, but the trajectory identified as best responder was chosen for definite implantation. Decision for D-lead was taken for complex symptoms in 45% and small therapeutic windows in 55% of patients. Directional position was achieved by external marking, controlled by lateral fluoroscopy and intra-surgical correction by clockwise rotation. Early after surgery D-lead mode was activated only in 30% of patients. Within the first 3 to 6 months, the latter increased to 71%. Analysis of the electric fields shows that the presumed volume of tissue activated (VTA) takes a symmetric shape (spheric ball or dumbbell-shape) in 33%, while 67% take a non-symmetric shape (semi-spheric or mushroom). This asymmetry leads to VTA steering in a medial direction in 55% of the cases.

Conclusion: While a narrow intra-surgical therapeutic window usually necessitates selection of another trajectory, D-lead implantation widens the surgical and therapeutic options and facilitates the decision for the trajectory with best response. Further, even when ring mode does not cause any side effects, the precise and efficient stimulation effects by D-mode led to its application in 71% within the first months after surgery. The theoretical calculation of the VTA reveals a high proportion of asymmetric electric fields, in the axial as well as in the cranio-caudal extensions.

References: Reinacher PC, Krüger MT, Coenen VA, Shah M, Roelz R, Jenkner C, Egger K: Determining the Orientation of Directional Deep Brain Stimulation Electrodes Using 3D Rotational Fluoroscopy. AJNR Am J Neuroradiol. 2017 Jun;38(6):1111-1116. Hellerbach A, Dembek TA, Hoevels M, Holz JA, Gierich A, Luyken K, Barbe MT, Wirths J, Visser-Vandewalle V, Treuer H: DiODe: Directional Orientation Detection of Segmented Deep Brain Stimulation Leads: A Sequential Algorithm Based on CT Imaging. Stereotact Funct Neurosurg. 2018; 96(5):335-341.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/directional-leads-in-deep-brain-stimulation-surgical-handling-and-evolving-therapy-options/