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Connor A. Wathen, Leonardo A. Frizon, Tanmoy K. Maiti, Kenneth B. Baker and Andre G. Machado

Ischemic stroke is a leading cause of disability worldwide, with profound economic costs. Poststroke motor impairment is the most commonly encountered deficit resulting in significant disability and is the primary driver of stroke-associated healthcare expenditures. Although many patients derive some degree of benefit from physical rehabilitation, a significant proportion continue to suffer from persistent motor impairment. Noninvasive brain stimulation, vagal nerve stimulation, epidural cortical stimulation, and deep brain stimulation (DBS) have all been studied as potential modalities to improve upon the benefits derived from physical therapy alone. These neuromodulatory therapies aim primarily to augment neuroplasticity and drive functional reorganization of the surviving perilesional cortex.

The authors have proposed a novel and emerging therapeutic approach based on cerebellar DBS targeted at the dentate nucleus. Their rationale is based on the extensive reciprocal connectivity between the dentate nucleus and wide swaths of cerebral cortex via the dentatothalamocortical and corticopontocerebellar tracts, as well as the known limitations to motor rehabilitation imposed by crossed cerebellar diaschisis. Preclinical studies in rodent models of ischemic stroke have shown that cerebellar DBS promotes functional recovery in a frequency-dependent manner, with the most substantial benefits of the therapy noted at 30-Hz stimulation. The improvements in motor function are paralleled by increased expression of markers of synaptic plasticity, synaptogenesis, and neurogenesis in the perilesional cortex. Given the findings of preclinical studies, a first-in-human trial, Electrical Stimulation of the Dentate Nucleus Area (EDEN) for Improvement of Upper Extremity Hemiparesis Due to Ischemic Stroke: A Safety and Feasibility Study, commenced in 2016. Although the existing preclinical evidence is promising, the results of this Phase I trial and subsequent clinical trials will be necessary to determine the future applicability of this therapy.

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Caio M. Matias, Leonardo A. Frizon, Sean J. Nagel, Darlene A. Lobel and André G. Machado

OBJECTIVE

The authors’ aim in this study was to evaluate placement accuracy and clinical outcomes in patients who underwent implantation of deep brain stimulation devices with the aid of frame-based stereotaxy and intraoperative MRI after induction of general anesthesia.

METHODS

Thirty-three patients with movement disorders (27 with Parkinson’s disease) underwent implantation of unilateral or bilateral deep brain stimulation systems (64 leads total). All patients underwent the implantation procedure with standard frame-based techniques under general anesthesia and without microelectrode recording. MR images were acquired immediately after the procedure and fused to the preoperative plan to verify accuracy. To evaluate clinical outcome, different scales were used to assess quality of life (EQ-5D), activities of daily living (Unified Parkinson’s Disease Rating Scale [UPDRS] part II), and motor function (UPDRS part III during off- and on-medication and off- and on-stimulation states). Accuracy was assessed by comparing the coordinates (x, y, and z) from the preoperative plan and coordinates from the tip of the lead on intraoperative MRI and postoperative CT scans.

RESULTS

The EQ-5D score improved or remained stable in 71% of the patients. When in the off-medication/on-stimulation state, all patients reported significant improvement in UPDRS III score at the last follow-up (p < 0.001), with a reduction of 25.2 points (46.3%) (SD 14.7 points and 23.5%, respectively). There was improvement or stability in the UPDRS II scores for 68% of the Parkinson’s patients. For 2 patients, the stereotactic error was deemed significant based on intraoperative MRI findings. In these patients, the lead was removed and replaced after correcting for the error during the same procedure. Postoperative lead revision was not necessary in any of the patients. Based on findings from the last intraoperative MRI study, the mean difference between the tip of the electrode and the planned target was 0.82 mm (SD 0.5 mm, p = 0.006) for the x-axis, 0.67 mm (SD 0.5 mm, p < 0.001) for the y-axis, and 0.78 mm (SD 0.7 mm, p = 0.008) for the z-axis. On average, the euclidian distance was 1.52 mm (SD 0.6 mm). In patients who underwent bilateral implantation, accuracy was further evaluated comparing the first implanted side and the second implanted side. There was a significant mediolateral (x-axis) difference (p = 0.02) in lead accuracy between the first (mean 1.02 mm, SD 0.57 mm) and the second (mean 0.66 mm, SD 0.50 mm) sides. However, no significant difference was found for the y- and z-axes (p = 0.10 and p = 0.89, respectively).

CONCLUSIONS

Frame-based DBS implantation under general anesthesia with intraoperative MRI verification of lead location is safe, accurate, precise, and effective compared with standard implantation performed using awake intraoperative physiology. More clinical trials are necessary to directly compare outcomes of each technique.

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James K. C. Liu, Hesham Soliman, Andre Machado, Milind Deogaonkar and Ali R. Rezai

Object

Many previous studies have shown that placement of deep brain stimulation (DBS) electrodes carries a considerable risk of hemorrhage. To date, no studies have evaluated the incidence of intracranial hemorrhage after removal of DBS electrodes. The authors performed a retrospective chart review to identify the incidence and trends in hemorrhage after DBS electrode removal.

Methods

A retrospective chart review of all DBS electrodes removed at the Cleveland Clinic between October 2000 and May 2010 was performed. All patients underwent postoperative CT scanning. Each patient was evaluated for age, sex, side of placement, target, duration of lead placement, reason for removal, and medical comorbidities.

Results

A total of 78 lead removals were performed in the 10-year period (1300 leads were implanted during the same period). Of the 78 leads removed, 10 (12.8%) resulted in hemorrhages seen on postoperative CT scans. The hemorrhages were superficial cortical in 6 cases of lead removal (60%) and deep in 4 cases (40%). No statistically significant correlation to any of the factors evaluated was found. All hemorrhages were asymptomatic. The authors' retrospective study of 78 DBS lead removals revealed a high risk of intracranial hemorrhage (12.8% per lead). The risk of hemorrhage during removal is significantly greater than the risk of hemorrhage during implantation (2.0% per lead at the authors' center during the same period). There were more superficial hemorrhages, and all hemorrhages were asymptomatic.

Conclusions

Removal of DBS leads carries a significantly higher risk of postoperative hemorrhages that are seen on images but are not clinically symptomatic.

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Caio M. Matias, Danilo Silva, Andre G. Machado and Scott E. Cooper

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) orglobus pallidus pars interna (GPi) is well established as a treatment for advanced Parkinson’s disease. In general, one of the 2 targets is chosen based on the clinical features of each patient. Stimulation of both targets could be viewed as redundant, given that the 2 targets are directly connected. However, it is possible that each target has different mechanisms, with clinical effects mediated by orthodromic or antidromic stimulation.

The authors report the case of a patient with severe Parkinson’s disease who had previously undergone bilateral subthalamic stimulation with excellent benefits. However, he presented with significant worsening associated with disease progression and pharmacological treatment, and then underwent bilateral GPi DBS. Follow-up assessment was conducted clinically as well as through blinded ratings of video recordings.

Pallidal DBS may be a safe and useful strategy to manage dystonic features and behavioral complications of subthalamic stimulation and pharmacological management. While combined stimulation was quite successful in the reported patient, further studies with larger samples and longer follow-up periods will be necessary before recommending the addition of pallidal DBS as a routine strategy for patients previously implanted with STN DBS.

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Leonardo A. Frizon, Sean J. Nagel, Francis J. May, Jianning Shao, Andres L. Maldonado-Naranjo, Hubert H. Fernandez and Andre G. Machado

OBJECTIVE

The number of patients who benefit from deep brain stimulation (DBS) for Parkinson’s disease (PD) has increased significantly since the therapy was first approved by the FDA. Suboptimal outcomes, infection, or device failure are risks of the procedure and may require lead removal or repositioning. The authors present here the results of their series of revision and reimplantation surgeries.

METHODS

The data were reviewed from all DBS intracranial lead removals, revisions, or reimplantations among patients with PD over a 6-year period at the authors’ institution. The indications for these procedures were categorized as infection, suboptimal outcome, and device failure. Motor outcomes as well as lead location were analyzed before removal and after reimplant or revision.

RESULTS

The final sample included 25 patients who underwent 34 lead removals. Thirteen patients had 18 leads reimplanted after removal. There was significant improvement in the motor scores after revision surgery among the patients who had the lead revised for a suboptimal outcome (p = 0.025). The mean vector distance of the new lead location compared to the previous location was 2.16 mm (SD 1.17), measured on an axial plane 3.5 mm below the anterior commissure–posterior commissure line. When these leads were analyzed by subgroup, the mean distance was 1.67 mm (SD 0.83 mm) among patients treated for infection and 2.73 mm (SD 1.31 mm) for those with suboptimal outcomes.

CONCLUSIONS

Patients with PD who undergo reimplantation surgery due to suboptimal outcome may experience significant benefits. Reimplantation after surgical infection seems feasible and overall safe.

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Rebecca L. Achey, Erin Yamamoto, Daniel Sexton, Christine Hammer, Bryan S. Lee, Robert S. Butler, Nicolas R. Thompson, Sean J. Nagel, Andre G. Machado and Darlene A. Lobel

OBJECTIVE

Deep brain stimulation (DBS) is an effective therapy for movement disorders such as idiopathic Parkinson’s disease (PD) and essential tremor (ET). However, some patients who demonstrate benefit on objective motor function tests do not experience postoperative improvement in depression or anxiety, 2 important components of quality of life (QOL). Thus, to examine other possible explanations for the lack of a post-DBS correlation between improved objective motor function and decreased depression or anxiety, the authors investigated whether patient perceptions of motor symptom severity might contribute to disease-associated depression and anxiety.

METHODS

The authors performed a retrospective chart review of PD and ET patients who had undergone DBS at the Cleveland Clinic in the period from 2009 to 2013. Patient demographics, diagnosis (PD, ET), motor symptom severity, and QOL measures (Primary Care Evaluation of Mental Disorders 9-item Patient Health Questionnaire [PHQ-9] for depression, Generalized Anxiety Disorder 7-item Scale [GAD-7], and patient-assessed tremor scores) were collected at 4 time points: preoperatively, postoperatively, 1-year follow-up, and 2-year follow-up. Multivariable prediction models with solutions for fixed effects were constructed to assess the correlation of predictor variables with PHQ-9 and GAD-7 scores. Predictor variables included age, sex, visit time, diagnosis (PD vs ET), patient-assessed tremor, physician-reported tremor, Unified Parkinson’s Disease Rating Scale part III (UPDRS-III) score, and patient-assessed tremor over time.

RESULTS

Seventy PD patients and 17 ET patients were included in this analysis. Mean postoperative and 1-year follow-up UPDRS-III and physician-reported tremor scores were significantly decreased compared with preoperative scores (p < 0.0001). Two-year follow-up physician-reported tremor was also significantly decreased from preoperative scores (p < 0.0001). Only a diagnosis of PD (p = 0.0047) and the patient-assessed tremor rating (p < 0.0001) were significantly predictive of depression. A greater time since surgery, in general, significantly decreased anxiety scores (p < 0.0001) except when a worsening of patient-assessed tremor was reported over the same time period (p < 0.0013).

CONCLUSIONS

Patient-assessed tremor severity alone was predictive of depression in PD and ET following DBS. This finding suggests that a patient’s perception of illness plays a greater role in depression than objective physical disability regardless of the time since surgical intervention. In addition, while anxiety may be attenuated by DBS, patient-assessed return of tremor over time can increase anxiety, highlighting the importance of long-term follow-up for behavioral health features in chronic neurological disorders. Together, these data suggest that the patient experience of motor symptoms plays a role in depression and anxiety—a finding that warrants consideration when evaluating, treating, and following movement disorder patients who are candidates for DBS.

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Rupesh Kotecha, Camille A. Berriochoa, Erin S. Murphy, Andre G. Machado, Samuel T. Chao, John H. Suh and Kevin L. Stephans

Patients with implanted neuromodulation devices present potential challenges for radiation therapy treatment planning and delivery. Although guidelines exist regarding the irradiation of cardiac pacemakers and defibrillators, fewer data and less clinical experience exist regarding the effects of radiation therapy on less frequently used devices, such as deep brain stimulators. A 79-year-old woman with a history of coarse tremors effectively managed with deep brain stimulation presented with multiple intracranial metastases from a newly diagnosed lung cancer and was referred for whole-brain radiation therapy. She was treated with a German helmet technique to a total dose of 30 Gy in 10 fractions using 6 MV photons via opposed lateral fields with the neurostimulator turned off prior to delivery of each fraction. The patient tolerated the treatment well with no acute complications and no apparent change in the functionality of her neurostimulator device or effect on her underlying neuromuscular disorder.

This represents the first reported case of the safe delivery of whole-brain radiation therapy in a patient with an implanted neurostimulator device. In cases such as this, neurosurgeons and radiation oncologists should have discussions with patients about the risks of brain injury, device malfunction or failure of the device, and plans for rigorous testing of the device before and after radiation therapy.

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Bryan S. Lee, Jaes Jones, Min Lang, Rebecca Achey, Lu Dai, Darlene A. Lobel, Sean J. Nagel, Andre G. Machado and Francois Bethoux

OBJECTIVE

Multiple sclerosis (MS) is a chronic autoimmune disease that causes demyelination and axonal loss. Walking difficulties are a common and debilitating symptom of MS; they are usually caused by spastic paresis of the lower extremities. Although intrathecal baclofen (ITB) therapy has been reported to be an effective treatment for spasticity in MS, there is limited published evidence regarding its effects on ambulation. The goal of this study was to characterize ITB therapy outcomes in ambulatory patients with MS.

METHODS

Data from 47 ambulatory patients with MS who received ITB therapy were analyzed retrospectively. Outcome measures included Modified Ashworth Scale, Spasm Frequency Scale, Numeric Pain Rating Scale, and the Timed 25-Foot Walk. Repeated-measures ANOVA was used to test for changes in outcome measures between baseline and posttreatment (6 months and 1 year). Significance was set at p < 0.05. Descriptive data are expressed as the mean ± SD, and results of the repeated-measures ANOVA tests and the Wilcoxon rank-sum test are expressed as the mean ± SEM.

RESULTS

There was a statistically significant reduction in the following variables: 1) aggregate lower-extremity Modified Ashworth Scale scores (from 14.8 ± 1.0 before ITB therapy to 5.8 ± 0.8 at 6 months posttreatment and 6.4 ± 0.9 at 1 year [p < 0.05]); 2) Numeric Pain Rating Scale scores (4.4 ± 0.5 before ITB, 2.8 ± 0.5 at 6 months, and 2.4 ± 0.4 at 1 year [p < 0.05]); 3) spasm frequency (45.7% of the patients reported a spasm frequency of ≥ 1 event per hour before ITB therapy, whereas 15.6% and 4.3% of the patients reported the same at 6 months and 1 year posttreatment, respectively [p < 0.05]); and 4) the number of oral medications taken for spasticity (p < 0.05). Of the 47 patients, 34 remained ambulatory at 6 months, and 32 at 1 year posttreatment. There was no statistically significant change in performance on the Timed 25-Foot Walk test over time for those patients who remained ambulatory.

CONCLUSIONS

In this retrospective study, the authors found that ITB therapy is effective in reducing spasticity and related symptoms in ambulatory patients with MS. Because the use of ITB therapy is increasing in ambulatory patients with MS, randomized, prospective studies are important to help provide a more useful characterization of the effects of ITB therapy on ambulation.