Artikel
Chronic directional subthalamic nucleus stimulation in Parkinson’s disease – a pilot study
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Veröffentlicht: | 8. Juni 2016 |
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Objective: Unwanted side effects, induced by current spread into adjacent structures, limit the efficacy of deep brain stimulation (DBS). In Parkinson’s disease (PD), the corticospinal tract and the medial lemniscus are correlated with motor and sensory side effects from subthalamic nucleus (STN) stimulation. Intraoperative studies provide evidence that directional steering of the electrical field can attenuate thresholds for both beneficial and side effects. In September 2015, a DBS system for chronic directional stimulation (Boston Scientific) became available for clinical use. Our pilot study aims to assess the therapeutic potential of this new technology and explore the surgical and radiologic specifics.
Method: As of now, three consecutive patients were included in the ongoing treatment study. DBS leads with a radiopaque marker were implanted employing standard procedures, resulting in the three segments of the directional lead facing anteriorly, posterolaterally and posteromedially. Intra- and postoperative x-rays and postoperative CCT were conducted to evaluate lead positioning and orientation. Randomized, double-blind monopolar reviews were conducted and therapeutic vs side effect thresholds were compared between uni- and omnidirectional stimulation. With the respective optimal settings established, patients entered a two-day double-blind crossover phase and were then asked to opt for their preferred mode of stimulation.
Results: Lead Implantation required minimal extra effort to ensure orientation of directional contacts per visual judgment. Developing a suitable procedure for postoperative verification of lead orientation proved difficult, as the orientation of the marker cannot be evaluated on conventional CT scans. During double-blind clinical testing, unidirectional steering led to increased side effect thresholds in all patients compared to omnidirectional stimulation. The blindly selected most favorable stimulation was posteromedial in two patients and anterior in one patient. After the blinded two-day crossover phase, all three patients opted for the directional stimulation.
Conclusions: This pilot study provides first evidence that chronic directional STN DBS in PD is safe, well tolerated, and increases the threshold for side effects, thus widening the therapeutic window in comparison to conventional DBS. All patients opted for directional stimulation after a blinded two-day trial. Larger studies with long-term follow-up are needed to confirm the results.