Abstract
Segmented deep brain stimulation leads feature directional electrodes that allow for a finer spatial control of electrical stimulation compared to traditional ring-shaped electrodes. These segmented leads have demonstrated enlarged therapeutic windows and have thus the potential to improve the treatment of Parkinson’s disease patients. Moreover, they provide a unique opportunity to record directional local field potentials. Here, we investigated whether directional local field potentials can help identify the best stimulation direction to assist device programming. Four Parkinson’s disease patients underwent routine implantation of the subthalamic nucleus. Firstly, local field potentials were recorded in three directions for two conditions: In one condition, the patient was at rest; in the other condition, the patient’s arm was moved. Secondly, current thresholds for therapeutic and side effects were identified intraoperatively for directional stimulation. Therapeutic windows were calculated from these two thresholds. Thirdly, the spectral power of the total beta band (13–35 Hz) and its sub-bands low, high, and peak beta were analyzed post hoc. Fourthly, the spectral power was used by different algorithms to predict the ranking of directions. The spectral power profiles were patient-specific, and spectral peaks were found both in the low beta band (13–20 Hz) and in the high beta band (20.5–35 Hz). The direction with the highest spectral power in the total beta band was most indicative of the 1st best direction when defined by therapeutic window. Based on the total beta band, the resting condition and the moving condition were similarly predictive about the direction ranking and classified 83.3% of directions correctly. However, different algorithms were needed to predict the ranking defined by therapeutic window or therapeutic current threshold. Directional local field potentials may help predict the best stimulation direction. Further studies with larger sample sizes are needed to better distinguish the informative value of different conditions and the beta sub-bands.
Highlights
Deep brain stimulation (DBS) of the subthalamic nucleus is an effective therapy for medically refractory cases of Parkinson’s disease (Deuschl, 2006; Weaver, 2009)
In contrast to the ranking above, we found ranking the directions from lowest to highest spectral power to be more predictive of the therapeutic current threshold
This study investigated directional local field potentials (LFPs) from the subthalamic nucleus and their potential to determine clinically effective stimulation directions
Summary
Deep brain stimulation (DBS) of the subthalamic nucleus is an effective therapy for medically refractory cases of Parkinson’s disease (Deuschl, 2006; Weaver, 2009). Even though modern stereotactic surgery can achieve sub-millimeter targeting accuracy (Nowacki et al, 2017), deviations of about 2 mm or more were reported for other surgical approaches (Guo et al, 2007; Lee et al, 2018) These deviations increase the likelihood of stimulation-induced side effects, which can affect up to 50% of implanted patients (Volkmann et al, 2009). Directional stimulation with segmented leads is a promising approach to address this issue (Contarino et al, 2014; Pollo et al, 2014; Nguyen et al, 2019a) It can reduce undesired activation of adjacent structures such as the internal capsule, and it has demonstrated higher side effect thresholds than classical omnidirectional stimulation in implanted patients (Steigerwald et al, 2016; Dembek et al, 2017). Directional stimulation may further be leveraged to target very specific and clinically effective regions of the subthalamic nucleus, known as “sweet spots” obtained from probabilistic mapping (Horn et al, 2017; Dembek et al, 2019; Nguyen et al, 2019b)
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