Background Subthalamic nucleus deep brain stimulation (STN‐DBS) is an effective therapy for selected Parkinson's disease patients with motor fluctuations, but can adversely affect speech and axial symptoms. The use of short pulse width (PW) has been shown to expand the therapeutic window acutely, but its utility in reducing side effects in chronic STN‐DBS patients has not been evaluated. Objective To compare the effect of short PW settings using 30‐μs with conventional 60‐μs settings on stimulation‐induced dysarthria in Parkinson's disease patients with previously implanted STN‐DBS systems. Methods In this single‐center, double‐blind, randomized crossover trial, we assigned 16 Parkinson's disease patients who had been on STN‐DBS for a mean of 6.5 years and exhibited moderate dysarthria to 30‐μs or 60‐μs settings for 4 weeks followed by the alternative PW setting for a further 4 weeks. The primary outcome was difference in dysarthric speech measured by the Sentence Intelligibility Test between study baseline and the 2 PW conditions. Secondary outcomes included motor, nonmotor, and quality of life measures. Results There was no difference in the Sentence Intelligibility Test scores between baseline and the 2 treatment conditions (P = 0.25). There were also no differences noted in motor, nonmotor, or quality of life scores. The 30‐μs settings were well tolerated, and adverse event rates were similar to those at conventional PW settings. Post hoc analysis indicated that patients with dysarthria and a shorter duration of DBS may be improved by short PW stimulation. Conclusions Short PW settings using 30 μs did not alter dysarthric speech in chronic STN‐DBS patients. A future study should evaluate whether patients with shorter duration of DBS may be helped by short PW settings. © 2019 International Parkinson and Movement Disorder Society

A BS TRACT: 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 stimulationinduced 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 preoptimization 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.

OBJECTIVE Suboptimal lead placement is one of the most common indications for deep brain stimulation (DBS) revision procedures. Confirming lead placement in relation to the visible anatomical target with dedicated stereotactic imaging before terminating the procedure can mitigate this risk. In this study, the authors examined the accuracy, precision, and safety of intraoperative MRI (iMRI) to both guide and verify lead placement during frame-based stereotactic surgery. METHODS A retrospective analysis of 650 consecutive DBS procedures for targeting accuracy, precision, and perioperative complications was performed. Frame-based lead placement took place in an operating room equipped with an MRI machine using stereotactic images to verify lead placement before removing the stereotactic frame. Immediate lead relocation was performed when necessary. Systematic analysis of the targeting error was calculated. RESULTS Verification of 1201 DBS leads with stereotactic MRI was performed in 643 procedures and with stereotactic CT in 7. The mean ± SD of the final targeting error was 0.9 ± 0.3 mm (range 0.1–2.3 mm). Anatomically acceptable lead placement was achieved with a single brain pass for 97% (n = 1164) of leads; immediate intraoperative relocation was performed in 37 leads (3%) to obtain satisfactory anatomical placement. General anesthesia was used in 91% (n = 593) of the procedures. Hemorrhage was noted after 4 procedures (0.6%); 3 patients (0.4% of procedures) presented with transient neurological symptoms, and 1 experienced delayed cognitive decline. Two bleeds coincided with immediate relocation (2 of 37 leads, 5.4%), which contrasts with hemorrhage in 2 (0.2%) of 1164 leads implanted on the first pass (p = 0.0058). Three patients had transient seizures in the postoperative period. The seizures coincided with hemorrhage in 2 of these patients and with immediate lead relocation in the other. There were 21 infections (3.2% of procedures, 1.5% in 3 months) leading to hardware removal. Delayed (> 3 months) retargeting of 6 leads (0.5%) in 4 patients (0.6% of procedures) was performed because of suboptimal stimulation benefit. There were no MRI-related complications, no permanent motor deficits, and no deaths. CONCLUSIONS To the authors’ knowledge, this is the largest series reporting the use of iMRI to guide and verify lead location during DBS surgery. It demonstrates a high level of accuracy, precision, and safety. Significantly higher hemorrhage was encountered when multiple brain passes were required for lead implantation, although none led to permanent deficit. Meticulous audit and calibration can improve precision and maximize safety.

Deep brain stimulation (DBS) is an effective surgical treatment in ameliorating symptoms of Parkinson's disease (PD), dystonia and tremor. DBS involves the surgical insertion of electrode(s) to stimulate either the subthalamic nucleus, globus pallidum interna or ventral intermediate nucleus of the thalamus, depending on the condition being treated. These structures play a critical role in the relay of electrical signals within the basal ganglia to facilitate movement. The mechanism by which DBS improves symptoms is not clearly understood. However, one notion is that the local effects of stimulation cause neuromodulation resulting in subsequent distant effects within connecting neural networks. Important factors to be considered when selecting patients for DBS include establishing a diagnosis, assessment of the patient's levodopa responsiveness if diagnosed with PD, neuropsychological and psychiatric evaluations, and a pre-DBS magnetic resonance imaging scan. Rare complications, such as intracranial haemorrhage, and common complications, such as infection, can occur. On balance, DBS is a highly effective and safe treatment for movement disorders; although, careful patient selection is critical.