A practical guide to troubleshooting pallidal deep brain stimulation issues in patients with dystonia

High frequency deep brain stimulation (DBS) of the internal portion of the globus pallidus has, in the last two decades, become a mainstream therapy for the management of medically-refractory dystonia syndromes. Such increasing uptake places an onus on movement disorder physicians to become familiar with this treatment modality, in particular optimal patient selection for the procedure and how to troubleshoot problems relating to sub-optimal efficacy and therapy-related side effects. Deep brain stimulation for dystonic conditions presents some unique challenges. For example, the frequent lack of immediate change in clinical status following stimulation alterations means that programming often relies on personal experience and local practice rather than real-time indicators of efficacy. Further, dystonia is a highly heterogeneous disorder, making the development of unifying guidelines and programming algorithms for DBS in this population difficult. Consequently, physicians may feel less confident in managing DBS for dystonia as compared to other indications e.g. Parkinson's disease. In this review, we integrate our years of personal experience of the programming of DBS systems for dystonia with a critical appraisal of the literature to produce a practical guide for troubleshooting common issues encountered in patients with dystonia treated with DBS, in the hope of improving the care for these patients

Novel Programming Features Help Alleviate Subthalamic Nucleus Stimulation‐Induced Side Effects

Background: Subthalamic nucleus deep brain stimulation (STN‐DBS) is a widely used treatment for Parkinsonʼs disease (PD) patients with motor complications, but can result in adverse effects (AEs) in a significant proportion of treated patients. The use of novel programming features including short pulse width (PW) and directional steering in alleviating stimulation‐induced AEs has not been explored. / Objective: To determine if programming with short PW, directional steering, or the combination of these novel techniques can improve stimulation‐induced dysarthria, dyskinesia, and pyramidal AEs. / Methods: Thirty‐two consecutive PD patients who experienced reversible AEs of STN‐DBS had optimization of their settings using either short PW, directional steering, or the combination, while ensuring equivalent control of motor symptoms. Pairwise comparisons of pre‐ and post‐optimization adverse effect ratings were made. Patients were left on the alternative setting with the greatest benefit and followed up at 6 months. Modeling of volume of tissue activated (VTA) and charge per pulse (Qp) calculations were used to explore potential underlying mechanisms of any differences found. / Results: There were significant improvements in stimulation‐induced dysarthria, dyskinesia, and pyramidal side effects after optimization. At 6 months, mean AE ratings remained significantly improved compared to pre‐optimization ratings. Different patterns of shift in VTA for each AE, and Qp could be used to explain improvements using novel techniques. / Conclusions: Stimulation‐induced dysarthria, dyskinesia, and pyramidal AEs induced by STN‐DBS can be improved by using novel programming techniques. These represent additional tools to conventional methods that can be used to address these AEs

Endurance of Short Pulse Width Thalamic Stimulation Efficacy in Intention Tremor

The benefit of short pulse width stimulation in patients suffering from essential tremor (ET) refractory to thalamic deep brain stimulation remains controversial. Here, we add to the minimal body of evidence available by reporting the effect of this type of stimulation in 3 patients with a persistent and severe intention tremor component despite iterative DBS setting adjustments. While a reduction in pulse width to 30 mus initially showed promise in these patients by improving tremor control and mitigating cerebellar side effects arguably by widening the therapeutic window, these benefits seemed to dissipate during early follow-up. Our experience supports the need for measuring longer-term outcomes when reporting the usefulness of this mode of stimulation in ET

Entraining stepping movements of Parkinson's patients to alternating subthalamic nucleus deep brain stimulation

Patients with advanced Parkinson's can be treated by deep brain stimulation of the subthalamic nucleus (STN). This affords a unique opportunity to record from this nucleus and stimulate it in a controlled manner. Previous work has shown that activity in the STN is modulated in a rhythmic pattern when Parkinson's patients perform stepping movements, raising the question whether the STN is involved in the dynamic control of stepping. To answer this question, we tested whether an alternating stimulation pattern resembling the stepping-related modulation of activity in the STN could entrain patients' stepping movements as evidence of the STN's involvement in stepping control. Group analyses of ten Parkinson's patients (one female) showed that alternating stimulation significantly entrained stepping rhythms. We found a remarkably consistent alignment between the stepping and stimulation cycle when the stimulation speed was close to the stepping speed in the five patients that demonstrated significant individual entrainment to the stimulation cycle. Our study suggests that the STN is causally involved in dynamic control of step timing, and motivates further exploration of this biomimetic stimulation pattern as a potential basis for the development of deep brain stimulation strategies to ameliorate gait impairments.SIGNIFICANCE STATEMENTWe test if the subthalamic nucleus in humans is causally involved in controlling stepping movements. To this end we studied patients with Parkinson's disease who have undergone therapeutic deep brain stimulation, as in these individuals we can stimulate the subthalamic nuclei in a controlled manner. We developed an alternating pattern of stimulation that mimics the pattern of activity modulation recorded in this nucleus during stepping. The alternating DBS could entrain patients' stepping rhythm, suggesting a causal role of the STN in dynamic gait control. This type of stimulation may potentially form the basis for improved DBS strategies for gait