Extended-release amantadine for OFF-related dystonia in Parkinson's disease

INTRODUCTION

Dystonia is a painful OFF-related complication in Parkinson's disease (PD) with limited treatment options.

METHODS

Post-hoc analysis using pooled data from two extended-release amantadine pivotal trials and follow-on open-label extension. Dystonia was assessed using the Unified Dyskinesia Rating Scale (UDysRS) Part 2 and the Movement Disorder Society-Unified PD Rating Scale (MDS-UPDRS) item 4.6.

RESULTS

Of 196 participants, 119 (60.7%) reported OFF-related dystonia at baseline per UDysRS. Twelve-week treatment with extended-release amantadine improved OFF dystonia (treatment differences vs placebo: UDysRS Part 2, -1.0 [-1.9,-0.1]; p = 0.03 and MDS-UPDRS Item 4.6, -0.3 [-0.6,-0.05]; p = 0.02). There was no correlation between changes in OFF time and changes in OFF dystonia. Double-blind improvements in OFF dystonia were sustained throughout the 2-year follow-up.

CONCLUSIONS

Extended-release amantadine yielded a sustained reduction in OFF-related dystonia in PD patients that was independent from a reduction in OFF time. A randomized controlled trial is warranted to confirm these findings.

Mapping dysfunctional circuits in the frontal cortex using deep brain stimulation

Frontal circuits play a critical role in motor, cognitive and affective processing, and their dysfunction may result in a variety of brain disorders. However, exactly which frontal domains mediate which (dys)functions remains largely elusive. We studied 534 deep brain stimulation electrodes implanted to treat four different brain disorders. By analyzing which connections were modulated for optimal therapeutic response across these disorders, we segregated the frontal cortex into circuits that had become dysfunctional in each of them. Dysfunctional circuits were topographically arranged from occipital to frontal, ranging from interconnections with sensorimotor cortices in dystonia, the primary motor cortex in Tourette's syndrome, the supplementary motor area in Parkinson's disease, to ventromedial prefrontal and anterior cingulate cortices in obsessive-compulsive disorder. Our findings highlight the integration of deep brain stimulation with brain connectomics as a powerful tool to explore couplings between brain structure and functional impairments in the human brain.

Mapping Dysfunctional Circuits in the Frontal Cortex Using Deep Brain Stimulation

Frontal circuits play a critical role in motor, cognitive, and affective processing - and their dysfunction may result in a variety of brain disorders. However, exactly which frontal domains mediate which (dys)function remains largely elusive. Here, we study 534 deep brain stimulation electrodes implanted to treat four different brain disorders. By analyzing which connections were modulated for optimal therapeutic response across these disorders, we segregate the frontal cortex into circuits that became dysfunctional in each of them. Dysfunctional circuits were topographically arranged from occipital to rostral, ranging from interconnections with sensorimotor cortices in dystonia, with the primary motor cortex in Tourette's syndrome, the supplementary motor area in Parkinson's disease, to ventromedial prefrontal and anterior cingulate cortices in obsessive-compulsive disorder. Our findings highlight the integration of deep brain stimulation with brain connectomics as a powerful tool to explore couplings between brain structure and functional impairment in the human brain.

Personalized chronic adaptive deep brain stimulation outperforms conventional stimulation in Parkinson's disease

Deep brain stimulation is a widely used therapy for Parkinson's disease (PD) but currently lacks dynamic responsiveness to changing clinical and neural states. Feedback control has the potential to improve therapeutic effectiveness, but optimal control strategy and additional benefits of "adaptive" neurostimulation are unclear. We implemented adaptive subthalamic nucleus stimulation, controlled by subthalamic or cortical signals, in three PD patients (five hemispheres) during normal daily life. We identified neurophysiological biomarkers of residual motor fluctuations using data-driven analyses of field potentials over a wide frequency range and varying stimulation amplitudes. Narrowband gamma oscillations (65-70 Hz) at either site emerged as the best control signal for sensing during stimulation. A blinded, randomized trial demonstrated improved motor symptoms and quality of life compared to clinically optimized standard stimulation. Our approach highlights the promise of personalized adaptive neurostimulation based on data-driven selection of control signals and may be applied to other neurological disorders.

Interactive mobile application for Parkinson's disease deep brain stimulation (MAP DBS): An open-label, multicenter, randomized, controlled clinical trial

INTRODUCTION

Deep brain stimulation (DBS) is an effective treatment for Parkinson's disease (PD), but its efficacy is tied to DBS programming, which is often time consuming and burdensome for patients, caregivers, and clinicians. Our aim is to test whether the Mobile Application for PD DBS (MAP DBS), a clinical decision support system, can improve programming.

METHODS

We conducted an open-label, 1:1 randomized, controlled, multicenter clinical trial comparing six months of SOC standard of care (SOC) to six months of MAP DBS-aided programming. We enrolled patients between 30 and 80 years old who received DBS to treat idiopathic PD at six expert centers across the United States. The primary outcome was time spent DBS programming and secondary outcomes measured changes in motor symptoms, caregiver strain and medication requirements.

RESULTS

We found a significant reduction in initial visit time (SOC: 43.8 ± 28.9 min n = 37, MAP DBS: 27.4 ± 13.0 min n = 35, p = 0.001). We did not find a significant difference in total programming time between the groups over the 6-month study duration. MAP DBS-aided patients experienced a significantly larger reduction in UPDRS III on-medication scores (-7.0 ± 7.9) compared to SOC (-2.7 ± 6.9, p = 0.01) at six months.

CONCLUSION

MAP DBS was well tolerated and improves key aspects of DBS programming time and clinical efficacy.

Targeting Accuracy and Clinical Outcomes of Awake Vs Asleep Interventional MRI-Guided Deep Brain Stimulation for Parkinson's Disease: The UCSF Experience

BACKGROUND

Interventional MRI (iMRI)-guided implantation of deep brain stimulator (DBS) leads has been developed to treat patients with Parkinson's disease (PD) without the need for awake testing.

OBJECTIVE

Direct comparisons of targeting accuracy and clinical outcomes for awake stereotactic with asleep iMRI-DBS for PD are limited.

METHODS

We performed a retrospective review of patients with PD who underwent awake or iMRI-guided DBS surgery targeting the subthalamic nucleus or globus pallidus interna between 2013 and 2019 at our institution. Outcome measures included Unified Parkinson's Disease Rating Scale Part III scores, levodopa equivalent daily dose, radial error between intended and actual lead locations, stimulation parameters, and complications.

RESULTS

Of the 218 patients included in the study, the iMRI cohort had smaller radial errors (iMRI: 1.27 ± 0.72 mm, awake: 1.59 ± 0.96 mm, P < .01) and fewer lead passes (iMRI: 1.0 ± 0.16, awake: 1.2 ± 0.41, P < .01). Changes in Unified Parkinson's Disease Rating Scale were similar between modalities, but awake cases had a greater reduction in levodopa equivalent daily dose than iMRI cases (P < .01), which was attributed to the greater number of awake subthalamic nucleus cases on multivariate analysis. Effective clinical contacts used for stimulation, side effect thresholds, and complication rates were similar between modalities.

CONCLUSION

Although iMRI-DBS may result in more accurate lead placement for intended target compared with awake-DBS, clinical outcomes were similar between surgical approaches. Ultimately, patient preference and surgeon experience with a given DBS technique should be the main factors when determining the "best" method for DBS implantation.

Benefits and Risks of a Staged‐Bilateral VIM versus Unilateral VIM DBS for Essential Tremor

Background

Despite over 30 years of clinical experience, high‐quality studies on the efficacy of bilateral versus unilateral deep brain stimulation (DBS) of the ventral intermediate (VIM) nucleus of the thalamus for medically refractory essential tremor (ET) remain limited.

Objectives

To compare benefits and risks of bilateral versus unilateral VIM DBS using the largest ET DBS clinical trial dataset available to date.

Methods

Participants from the US St. Jude/Abbott pivotal ET DBS trial who underwent staged‐bilateral VIM implantation constituted the primary cohort in this sub‐analysis. Their assessments “on” DBS at six months after second‐side VIM DBS implantation were compared to the assessments six months after unilateral implantation. Two control cohorts of participants with unilateral implantation only were also used for between‐group comparisons.

Results

The primary cohort consisted of n = 38 ET patients (22M/16F; age of 65.3 ± 9.5 years). The second side VIM‐DBS resulted in a 29.6% additional improvement in the total motor CRST score (P < 0.001), with a 64.1% CRST improvement in the contralateral side (P < 0.001). An added improvement was observed in the axial tremor score (21.4%, P = 0.005), and CRST part B (24.8%, P < 0.001) score. Rate of adverse events was slightly higher after bilateral stimulation.

Conclusions

In the largest ET DBS study to date, staged‐bilateral VIM DBS was a highly effective treatment for ET with bilateral implantation resulting in greater reduction in total motor tremor scores when compared to unilateral stimulation alone.

Elevated Mood States in Patients With Parkinson's Disease Treated With Deep Brain Stimulation: Diagnosis and Management Strategies

OBJECTIVE

Deep brain stimulation (DBS) is an effective surgical treatment for patients with Parkinson's disease (PD). DBS therapy, particularly with the subthalamic nucleus (STN) target, has been linked to rare psychiatric complications, including depression, impulsivity, irritability, and suicidality. Stimulation-induced elevated mood states can also occur. These episodes rarely meet DSM-5 criteria for mania or hypomania.

METHODS

The investigators conducted a chart review of 82 patients with PD treated with DBS.

RESULTS

Nine (11%) patients developed stimulation-induced elevated mood. Five illustrative cases are described (all males with STN DBS; mean age=62.2 years [SD=10.5], mean PD duration=8.6 years [SD=1.6]). Elevated mood states occurred during or shortly after programming changes, when more ventral contacts were used (typically in monopolar mode) and lasted minutes to months. Four patients experienced elevated mood at low amplitudes (1.0 V/1.0 mA); all had psychiatric risk factors (history of impulse-control disorder, dopamine dysregulation syndrome, substance use disorder, and/or bipolar diathesis) that likely contributed to mood destabilization.

CONCLUSIONS

Preoperative DBS evaluations should include a thorough assessment of psychiatric risk factors. The term "stimulation-induced elevated mood states" is proposed to describe episodes of elevated, expansive, or irritable mood and psychomotor agitation that occur during or shortly after DBS programming changes and may be associated with increased goal-directed activity, impulsivity, grandiosity, pressured speech, flight of ideas, or decreased need for sleep and may persist beyond stimulation adjustments. This clinical phenomenon should be considered for inclusion in the bipolar disorder category in future DSM revisions, allowing for increased recognition and appropriate management.

Prefrontal Physiomarkers of Anxiety and Depression in Parkinson's Disease

Objective: Anxiety and depression are prominent non-motor symptoms of Parkinson’s disease (PD), but their pathophysiology remains unclear. We sought to understand their neurophysiological correlates from chronic invasive recordings of the prefrontal cortex (PFC).

Methods: We studied four patients undergoing deep brain stimulation (DBS) for their motor signs, who had comorbid mild to moderate anxiety and/or depressive symptoms. In addition to their basal ganglia leads, we placed a permanent prefrontal subdural 4-contact lead. These electrodes were attached to an investigational pulse generator with the capability to sense and store field potential signals, as well as deliver therapeutic neurostimulation. At regular intervals over 3–5 months, participants paired brief invasive neural recordings with self-ratings of symptoms related to depression and anxiety.

Results: Mean age was 61 ± 7 years, mean disease duration was 11 ± 8 years and a mean Unified Parkinson’s Disease Rating Scale, with part III (UPDRS-III) off medication score of 37 ± 13. Mean Beck Depression Inventory (BDI) score was 14 ± 5 and Beck Anxiety Index was 16.5 ± 5. Prefrontal cortex spectral power in the beta band correlated with patient self-ratings of symptoms of depression and anxiety, with r-values between 0.31 and 0.48. Mood scores showed negative correlation with beta spectral power in lateral locations, and positive correlation with beta spectral power in a mesial recording location, consistent with the dichotomous organization of reward networks in PFC.

Interpretation: These findings suggest a physiological basis for anxiety and depression in PD, which may be useful in the development of neurostimulation paradigms for these non-motor disease features.

Enhancing clinical information display to improve patient encounters: human-centered design and evaluation of the Parkinson’s Disease-BRIDGE platform (Preprint)

Background

People with Parkinson disease (PD) have a variety of complex medical problems that require detailed review at each clinical encounter for appropriate management. Care of other complex conditions has benefited from digital health solutions that efficiently integrate disparate clinical information. Although various digital approaches have been developed for research and care in PD, no digital solution to personalize and improve communication in a clinical encounter is readily available.

Objective

We intend to improve the efficacy and efficiency of clinical encounters with people with PD through the development of a platform (PD-BRIDGE) with personalized clinical information from the electronic health record (EHR) and patient-reported outcome (PRO) data.

Methods

Using human-centered design (HCD) processes, we engaged clinician and patient stakeholders in developing PD-BRIDGE through three phases: an inspiration phase involving focus groups and discussions with people having PD, an ideation phase generating preliminary mock-ups for feedback, and an implementation phase testing the platform. To qualitatively evaluate the platform, movement disorders neurologists and people with PD were sent questionnaires asking about the technical validity, usability, and clinical relevance of PD-BRIDGE after their encounter.

Results

The HCD process led to a platform with 4 modules. Among these, 3 modules that pulled data from the EHR include a longitudinal module showing motor ratings over time, a display module showing the most recently collected clinical rating scales, and another display module showing relevant laboratory values and diagnoses; the fourth module displays motor symptom fluctuation based on an at-home diary. In the implementation phase, PD-BRIDGE was used in 17 clinical encounters for patients cared for by 1 of 11 movement disorders neurologists. Most patients felt that PD-BRIDGE facilitated communication with their clinician (n=14, 83%) and helped them understand their disease trajectory (n=11, 65%) and their clinician’s recommendations (n=11, 65%). Neurologists felt that PD-BRIDGE improved their ability to understand the patients’ disease course (n=13, 75% of encounters), supported clinical care recommendations (n=15, 87%), and helped them communicate with their patients (n=14, 81%). In terms of improvements, neurologists noted that data in PD-BRIDGE were not exhaustive in 62% (n=11) of the encounters.

Conclusions

Integrating clinically relevant information from EHR and PRO data into a visually efficient platform (PD-BRIDGE) can facilitate clinical encounters with people with PD. Developing new modules with more disparate information could improve these complex encounters even further.

Long-term wireless streaming of neural recordings for circuit discovery and adaptive stimulation in individuals with Parkinson's disease

Neural recordings using invasive devices in humans can elucidate the circuits underlying brain disorders, but have so far been limited to short recordings from externalized brain leads in a hospital setting or from implanted sensing devices that provide only intermittent, brief streaming of time series data. Here, we report the use of an implantable two-way neural interface for wireless, multichannel streaming of field potentials in five individuals with Parkinson's disease (PD) for up to 15 months after implantation. Bilateral four-channel motor cortex and basal ganglia field potentials streamed at home for over 2,600 h were paired with behavioral data from wearable monitors for the neural decoding of states of inadequate or excessive movement. We validated individual-specific neurophysiological biomarkers during normal daily activities and used those patterns for adaptive deep brain stimulation (DBS). This technological approach may be widely applicable to brain disorders treatable by invasive neuromodulation.

Embedded adaptive deep brain stimulation for cervical dystonia controlled by motor cortex theta oscillations

Dystonia is a disabling movement disorder characterized by excessive muscle contraction for which the underlying pathophysiology is incompletely understood and treatment interventions limited in efficacy. Here we utilize a novel, sensing-enabled, deep brain stimulator device, implanted in a patient with cervical dystonia, to record local field potentials from chronically implanted electrodes in the sensorimotor cortex and subthalamic nuclei bilaterally. This rechargeable device was able to record large volumes of neural data at home, in the naturalistic environment, during unconstrained activity. We confirmed the presence of theta (3-7 Hz) oscillatory activity, which was coherent throughout the cortico-subthalamic circuit and specifically suppressed by high-frequency stimulation. Stimulation also reduced the duration, rate and height of theta bursts. These findings motivated a proof-of-principle trial of a new form of adaptive deep brain stimulation - triggered by theta-burst activity recorded from the motor cortex. This facilitated increased peak stimulation amplitudes without induction of dyskinesias and demonstrated improved blinded clinical ratings compared to continuous DBS, despite reduced total electrical energy delivered. These results further strengthen the pathophysiological role of low frequency (theta) oscillations in dystonia and demonstrate the potential for novel adaptive stimulation strategies linked to cortico-basal theta bursts.

The Impact of Deep Brain Stimulation on Sleep in Parkinson's Disease: An update

Background:

Parkinson’s disease (PD) can have a significant impact on sleep. Deep brain stimulation (DBS) is an effective treatment for motor features of PD, but less is understood about the impact DBS may have on sleep architecture and various sleep issues commonly seen in PD.

Objective:

To review the impact of DBS on various sleep issues in PD.

Methods:

We reviewed the literature regarding the impact of DBS on sleep patterns, nocturnal motor and non-motor symptoms, and sleep disorders in PD.

Results:

Objective sleep measures on polysomnography (PSG), including sleep latency and wake after sleep onset improve after subthalamic nucleus (STN) and globus pallidus interna (GPi) DBS. Subjective sleep measures, nocturnal motor symptoms, and some non-motor symptoms (nocturia) also may improve. Current evidence suggests STN DBS has no impact on Rapid Eye Movement Behavior Disorder (RBD), while STN DBS may improve symptoms of Restless Legs Syndrome (RLS). There are no studies that have evaluated the impact of GPi DBS on RBD, while it is unclear if GPi has an effect on RLS in PD.

Conclusion:

DBS therapy at either site appears to improve objective and subjective sleep parameters in patients with PD. Most likely, the improvement of motor and some non-motor nocturnal symptoms leads to an increase in total sleep time by up to an hour, as well as reduction of sleep fragmentation. DBS most likely has no impact on RBD, while there is evidence that STN DBS appears to help reduce RLS severity. Further studies are needed.

Structural connectivity predicts clinical outcomes of deep brain stimulation for Tourette syndrome

Deep brain stimulation may be an effective therapy for select cases of severe, treatment-refractory Tourette syndrome; however, patient responses are variable, and there are no reliable methods to predict clinical outcomes. The objectives of this retrospective study were to identify the stimulation-dependent structural networks associated with improvements in tics and comorbid obsessive-compulsive behaviour, compare the networks across surgical targets, and determine if connectivity could be used to predict clinical outcomes. Volumes of tissue activated for a large multisite cohort of patients (n = 66) implanted bilaterally in globus pallidus internus (n = 34) or centromedial thalamus (n = 32) were used to generate probabilistic tractography to form a normative structural connectome. The tractography maps were used to identify networks that were correlated with improvement in tics or comorbid obsessive-compulsive behaviour and to predict clinical outcomes across the cohort. The correlated networks were then used to generate 'reverse' tractography to parcellate the total volume of stimulation across all patients to identify local regions to target or avoid. The results showed that for globus pallidus internus, connectivity to limbic networks, associative networks, caudate, thalamus, and cerebellum was positively correlated with improvement in tics; the model predicted clinical improvement scores (P = 0.003) and was robust to cross-validation. Regions near the anteromedial pallidum exhibited higher connectivity to the positively correlated networks than posteroventral pallidum, and volume of tissue activated overlap with this map was significantly correlated with tic improvement (P < 0.017). For centromedial thalamus, connectivity to sensorimotor networks, parietal-temporal-occipital networks, putamen, and cerebellum was positively correlated with tic improvement; the model predicted clinical improvement scores (P = 0.012) and was robust to cross-validation. Regions in the anterior/lateral centromedial thalamus exhibited higher connectivity to the positively correlated networks, but volume of tissue activated overlap with this map did not predict improvement (P > 0.23). For obsessive-compulsive behaviour, both targets showed that connectivity to the prefrontal cortex, orbitofrontal cortex, and cingulate cortex was positively correlated with improvement; however, only the centromedial thalamus maps predicted clinical outcomes across the cohort (P = 0.034), but the model was not robust to cross-validation. Collectively, the results demonstrate that the structural connectivity of the site of stimulation are likely important for mediating symptom improvement, and the networks involved in tic improvement may differ across surgical targets. These networks provide important insight on potential mechanisms and could be used to guide lead placement and stimulation parameter selection, as well as refine targets for neuromodulation therapies for Tourette syndrome.

Thalamic deep brain stimulation for acquired dystonia in children and young adults: a phase 1 clinical trial

OBJECTIVE

The aim of this study was to evaluate the feasibility and preliminary efficacy and safety of combined bilateral ventralis oralis posterior/ventralis intermedius (Vop/Vim) deep brain stimulation (DBS) for the treatment of acquired dystonia in children and young adults. Pallidal DBS is efficacious for severe, medication-refractory isolated dystonia, providing 50%-60% long-term improvement. Unfortunately, pallidal stimulation response rates in acquired dystonia are modest and unpredictable, with frequent nonresponders. Acquired dystonia, most commonly caused by cerebral palsy, is more common than isolated dystonia in pediatric populations and is more recalcitrant to standard treatments. Given the limitations of pallidal DBS in acquired dystonia, there is a need to explore alternative brain targets. Preliminary evidence has suggested that thalamic stimulation may be efficacious for acquired dystonia.

METHODS

Four participants, 3 with perinatal brain injuries and 1 with postencephalitic symptomatic dystonia, underwent bilateral Vop/Vim DBS and bimonthly evaluations for 12 months. The primary efficacy outcome was the change in Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Barry-Albright Dystonia Scale (BADS) scores between the baseline and 12-month assessments. Video documentation was used for blinded ratings. Secondary outcomes included evaluation of spasticity (Modified Ashworth Scale score), quality of life (Pediatric Quality of Life Inventory [PedsQL] and modified Unified Parkinson's Disease Rating Scale Part II [UPDRS-II] scores), and neuropsychological assessments. Adverse events were monitored for safety.

RESULTS

All participants tolerated the procedure well, and there were no safety concerns or serious adverse events. There was an average improvement of 21.5% in the BFMDRS motor subscale score, but the improvement was only 1.6% according to the BADS score. Following blinded video review, dystonia severity ratings were even more modest. Secondary outcomes, however, were more encouraging, with the BFMDRS disability subscale score improving by 15.7%, the PedsQL total score by 27%, and the modified UPDRS-II score by 19.3%. Neuropsychological assessment findings were unchanged 1 year after surgery.

CONCLUSIONS

Bilateral thalamic neuromodulation by DBS for severe, medication-refractory acquired dystonia was well tolerated. Primary and secondary outcomes showed highly variable treatment effect sizes comparable to those of pallidal stimulation in this population. As previously described, improvements in quality of life and disability were not reflected in dystonia severity scales, suggesting a need for the development of scales specifically for acquired dystonia.Clinical trial registration no.: NCT03078816 (clinicaltrials.gov).

Recommendations for Deep Brain Stimulation Device Management During a Pandemic

Most medical centers are postponing elective procedures and deferring non-urgent clinic visits to conserve hospital resources and prevent spread of COVID-19. The pandemic crisis presents some unique challenges for patients currently being treated with deep brain stimulation (DBS). Movement disorder (Parkinson’s disease, essential tremor, dystonia), neuropsychiatric disorder (obsessive compulsive disorder, Tourette syndrome, depression), and epilepsy patients can develop varying degrees of symptom worsening from interruption of therapy due to neurostimulator battery reaching end of life, device malfunction or infection. Urgent intervention to maintain or restore stimulation may be required for patients with Parkinson’s disease who can develop a rare but potentially life-threatening complication known as DBS-withdrawal syndrome. Similarly, patients with generalized dystonia can develop status dystonicus, patients with obsessive compulsive disorder can become suicidal, and epilepsy patients can experience potentially life-threatening worsening of seizures as a result of therapy cessation. DBS system infection can require urgent, and rarely emergent surgery. Elective interventions including new implantations and initial programming should be postponed. For patients with existing DBS systems, the battery status and electrical integrity interrogation can now be performed using patient programmers, and employed through telemedicine visits or by phone consultations. The decision for replacement of the implantable pulse generator to prevent interruption of DBS therapy should be made on a case-by-case basis taking into consideration battery status and a patient’s tolerance to potential therapy disruption. Scheduling of the procedures, however, depends heavily on the hospital system regulations and on triage procedures with respect to safety and resource utilization during the health crisis.

Secondary Worsening Following DYT1 Dystonia Deep Brain Stimulation: A Multi-country Cohort

Objective: To reveal clinical characteristics of suboptimal responses to deep brain stimulation (DBS) in a multi-country DYT1 dystonia cohort. Methods: In this multi-country multi-center retrospective study, we analyzed the clinical data of DYT1 patients who experienced suboptimal responses to DBS defined as <30% improvement in dystonia scales at the last follow-up compared with baseline. We used a literature-driven historical cohort of 112 DYT1 patients for comparison. Results: Approximately 8% of our study cohort (11 out of 132) experienced suboptimal responses to DBS. Compared with the historical cohort, the multi-country cohort with suboptimal responses had a significantly younger age at onset (mean, 7.0 vs. 8.4 years; p = 0.025) and younger age at DBS (mean, 12.0 vs. 18.6 years; p = 0.019). Additionally, cranial involvement was more common in the multi-country cohort (before DBS, 64% vs. 45%, p = 0.074; before or after DBS, 91% vs. 47%, p = 0.001). Mean motor improvement at the last follow-up from baseline were 0% and 66% for the multi-country and historical cohorts, respectively. All 11 patients of the multi-country cohort had generalization of dystonia within 2.5 years after disease onset. All patients experienced dystonia improvement of >30% postoperatively; however, secondary worsening of dystonia commenced between 6 months and 3 years following DBS. The improvement at the last follow-up was less than 30% despite optimally-placed leads, a trial of multiple programming settings, and additional DBS surgeries in all patients. The on-/off-stimulation comparison at the long-term follow-up demonstrated beneficial effects of DBS despite missing the threshold of 30% improvement over baseline. Conclusion: Approximately 8% of patients represent a more aggressive phenotype of DYT1 dystonia characterized by younger age at onset, faster disease progression, and cranial involvement, which seems to be associated with long-term suboptimal responses to DBS (e.g., secondary worsening). This information could be useful for both clinicians and patients in clinical decision making and patient counseling before and following DBS implantations. Patients with this phenotype may have different neuroplasticity, neurogenetics, or possibly distinct neurophysiology.

Subthalamic nucleus deep brain stimulation with a multiple independent constant current-controlled device in Parkinson's disease (INTREPID): a multicentre, double-blind, randomised, sham-controlled study

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus is an established therapeutic option for managing motor symptoms of Parkinson's disease. We conducted a double-blind, sham-controlled, randomised controlled trial to assess subthalamic nucleus DBS, with a novel multiple independent contact current-controlled (MICC) device, in patients with Parkinson's disease.

METHODS

This trial took place at 23 implanting centres in the USA. Key inclusion criteria were age between 22 and 75 years, a diagnosis of idiopathic Parkinson's disease with over 5 years of motor symptoms, and stable use of anti-parkinsonian medications for 28 days before consent. Patients who passed screening criteria were implanted with the DBS device bilaterally in the subthalamic nucleus. Patients were randomly assigned in a 3:1 ratio to receive either active therapeutic stimulation settings (active group) or subtherapeutic stimulation settings (control group) for the 3-month blinded period. Randomisation took place with a computer-generated data capture system using a pre-generated randomisation table, stratified by site with random permuted blocks. During the 3-month blinded period, both patients and the assessors were masked to the treatment group while the unmasked programmer was responsible for programming and optimisation of device settings. The primary outcome was the difference in mean change from baseline visit to 3 months post-randomisation between the active and control groups in the mean number of waking hours per day with good symptom control and no troublesome dyskinesias, with no increase in anti-parkinsonian medications. Upon completion of the blinded phase, all patients received active treatment in the open-label period for up to 5 years. Primary and secondary outcomes were analysed by intention to treat. All patients who provided informed consent were included in the safety analysis. The open-label phase is ongoing with no new enrolment, and current findings are based on the prespecified interim analysis of the first 160 randomly assigned patients. The study is registered with ClinicalTrials.gov, NCT01839396.

FINDINGS

Between May 17, 2013, and Nov 30, 2017, 313 patients were enrolled across 23 sites. Of these 313 patients, 196 (63%) received the DBS implant and 191 (61%) were randomly assigned. Of the 160 patients included in the interim analysis, 121 (76%) were randomly assigned to the active group and 39 (24%) to the control group. The difference in mean change from the baseline visit (post-implant) to 3 months post-randomisation in increased ON time without troublesome dyskinesias between the active and control groups was 3·03 h (SD 4·52, 95% CI 1·3-4·7; p<0·0001). 26 serious adverse events in 20 (13%) patients occurred during the 3-month blinded period. Of these, 18 events were reported in the active group and 8 in the control group. One death was reported among the 196 patients before randomisation, which was unrelated to the procedure, device, or stimulation.

INTERPRETATION

This double-blind, sham-controlled, randomised controlled trial provides class I evidence of the safety and clinical efficacy of subthalamic nucleus DBS with a novel MICC device for the treatment of motor symptoms of Parkinson's disease. Future trials are needed to investigate potential benefits of producing a more defined current field using MICC technology, and its effect on clinical outcomes.

FUNDING

Boston Scientific.

Phenomenology and Management of Subthalamic Stimulation-Induced Dyskinesia in Patients With Isolated Dystonia

Background

The pallidum has been the preferred DBS target for dystonia, but recent studies have shown equal or greater improvement in patients implanted in the STN.¹ Transient stimulation-induced dyskinesia (SID) is frequently observed when stimulating this novel target, and there are no previously published video case reports of this phenomenon.

Cases

We describe in detail the SID phenomenology experienced by 4 patients who had been implanted with STN DBS for isolated dystonia.

Conclusions

SID can occur in focal, segmental, axial, or generalized distribution, can resemble levodopa-induced dyskinesia choreiform or dystonic movements observed in Parkinson's disease, and is generally transient and resolves with customized DBS programming. Providers should be aware that SID can occur after STN DBS when treating isolated dystonia and not assume movements are the result of worsening or spread of the underlying dystonia.

Ages at Onset of Anxiety and Depressive Disorders in Parkinson's Disease

OBJECTIVE

Parkinson's disease (PD) is a quintessential neuropsychiatric condition in which anxiety and depressive symptoms are common and may precede motor manifestations. The authors explored the ages at onset of anxiety and depressive disorders among patients with PD evaluated by psychiatrists at a deep brain stimulation center.

METHODS

Psychiatric diagnoses and ages at onset were collected via clinical interviews. The ages at PD diagnosis were ascertained by chart review. Onset ages for anxiety and depressive disorders (overall and for specific disorders) were compared with patients' ages at PD diagnosis by using t tests. Onset ages for major depressive disorder (MDD), generalized anxiety disorder (GAD), and panic disorder were compared with typical onset ages in the general population by using the sign test. A total of 108 patients (66.7% men; age 63.7 years [SD=8.9]) were included in the analysis.

RESULTS

Anxiety and depressive disorders occurred significantly earlier than PD diagnoses. Among patients whose anxiety and depression predated motor symptoms, the mean age at onset of anxiety disorders was 25.6 years earlier, and the mean age at onset of depressive disorders was 17.6 years earlier compared with the mean age at PD diagnosis (both p values <0.0001). Median onset ages for MDD (p<0.0001), GAD (p=0.0002), and panic disorder (p=0.0005) were significantly higher than typical median onset ages in the general population.

CONCLUSIONS

These results may indicate that neurodegenerative changes are present in parts of the brainstem reticular core and limbic system before motor circuits are affected to a degree that causes motor symptoms. Psychiatrists should be mindful that onset of MDD, GAD, and panic disorder after age 45 might signal a neurodegenerative movement disorder such as PD.

Surgical Treatment of Parkinson Disease

Surgery in Parkinson disease is effective for a select group of patients when optimal medical management is not sufficient. Functional neurosurgery can be used as either a salvage therapy in patients with disabling symptoms or to maintain quality of life and independence before progression to severe disability in high-functioning patients. With recent technological advancements in imaging and targeting as well as novel neuromodulation paradigms, there are numerous options for targeted brain lesions and deep brain stimulation. Surgical decision making and postoperative management in Parkinson disease therefore often requires a multidisciplinary team effort with neurology, neurosurgery, neuropsychology, and psychiatry.

Cerebellar Deep Brain Stimulation for Acquired Hemidystonia

Background

The cerebellum's role in dystonia is increasingly recognized. Dystonia can be a disabling and refractory condition; deep brain stimulation can help many patients, but it is traditionally less effective in acquired dystonia. New surgical targets would be instrumental in providing treatment options and understanding dystonia further.

Objective

To evaluate the efficacy of deep brain stimulation of the cerebellum in acquired dystonia.

Methods

We report our management of a 37-year-old woman with severe left arm and leg dystonia, a complication of an ischemic stroke in childhood. She had already had 2 thalamotomies with only transient benefit. These procedures, in addition to her initial stroke that had damaged the basal ganglia, left traditional deep brain stimulation targets unavailable.

Results

After implantation of bilateral deep cerebellar nuclei, dystonia improved with a 40% reduction in severity on scales and subjective reports of improved posturing, gait, and pain. This improvement has been maintained for almost 2 years after implantation.

Conclusion

Cerebellar stimulation has potential for therapeutic benefit in acquired dystonia and should be further explored.

Image-based analysis and long-term clinical outcomes of deep brain stimulation for Tourette syndrome: a multisite study

BACKGROUND

Deep brain stimulation (DBS) can be an effective therapy for tics and comorbidities in select cases of severe, treatment-refractory Tourette syndrome (TS). Clinical responses remain variable across patients, which may be attributed to differences in the location of the neuroanatomical regions being stimulated. We evaluated active contact locations and regions of stimulation across a large cohort of patients with TS in an effort to guide future targeting.

METHODS

We collected retrospective clinical data and imaging from 13 international sites on 123 patients. We assessed the effects of DBS over time in 110 patients who were implanted in the centromedial (CM) thalamus (n=51), globus pallidus internus (GPi) (n=47), nucleus accumbens/anterior limb of the internal capsule (n=4) or a combination of targets (n=8). Contact locations (n=70 patients) and volumes of tissue activated (n=63 patients) were coregistered to create probabilistic stimulation atlases.

RESULTS

Tics and obsessive-compulsive behaviour (OCB) significantly improved over time (p<0.01), and there were no significant differences across brain targets (p>0.05). The median time was 13 months to reach a 40% improvement in tics, and there were no significant differences across targets (p=0.84), presence of OCB (p=0.09) or age at implantation (p=0.08). Active contacts were generally clustered near the target nuclei, with some variability that may reflect differences in targeting protocols, lead models and contact configurations. There were regions within and surrounding GPi and CM thalamus that improved tics for some patients but were ineffective for others. Regions within, superior or medial to GPi were associated with a greater improvement in OCB than regions inferior to GPi.

CONCLUSION

The results collectively indicate that DBS may improve tics and OCB, the effects may develop over several months, and stimulation locations relative to structural anatomy alone may not predict response. This study was the first to visualise and evaluate the regions of stimulation across a large cohort of patients with TS to generate new hypotheses about potential targets for improving tics and comorbidities.

Globus Pallidus Interna or Subthalamic Nucleus Deep Brain Stimulation for Parkinson Disease: A Review

Importance

Selection of the best deep brain stimulation (DBS) target-subthalamic nucleus (STN) or globus pallidus interna (GPi)-for treatment of motor complications in Parkinson disease remains a matter of debate.

Observations

Increasing evidence from randomized clinical trials indicates that motor benefit is similar between both targets, including an effect on dyskinesia and improvement in quality of life. Deep brain stimulation of the STN offers consistently greater dopaminergic medication reduction, possible mild benefit in nonmotor domains, and potential economic advantage. Deep brain stimulation of the GPi provides a probable advantage in dyskinesia suppression, management of symptoms with unilateral leads, and flexibility in medications and programming adjustments. Overall, STN DBS is at potentially higher or equal risk for neuropsychiatric changes compared with GPi DBS.

Conclusions and Relevance

Both GPi and STN DBS provide similar, consistent, marked motor benefits, but subtle target differences exist. Target selection should be tailored to each patient's clinical presentation, neuropsychiatric profile, and goals of surgery, allowing customization of this therapy and improved individual outcomes.

Washout of chronic therapeutic deep brain stimulation increases cortical phase-amplitude coupling

Invasive human brain recordings have shown that acute therapeutic deep brain stimulation (DBS) reduces cortical synchronization, measured by coupling of beta phase to gamma amplitude. Here we show by noninvasive scalp electroencephalography that withdrawal of chronic DBS elevates phase-amplitude coupling, in proportion to the worsening of contralateral rigidity.

Patient Experience with Rechargeable Implantable Pulse Generator Deep Brain Stimulation for Movement Disorders

BACKGROUND/AIMS

Nonrechargeable deep brain stimulation implantable pulse generators (IPGs) for movement disorders require surgical replacement every few years due to battery depletion. Rechargeable IPGs reduce frequency of replacement surgeries and inherent risks of complications but require frequent recharging. Here, we evaluate patient experience with rechargeable IPGs and define predictive characteristics for higher satisfaction.

METHODS

We contacted all patients implanted with rechargeable IPGs at a single center in a survey-based study. We analyzed patient satisfaction with respect to age, diagnosis, target, charging duration, and body mass index. We tabulated hardware-related adverse events.

RESULTS

Dystonia patients had significantly higher satisfaction than Parkinson's disease patients in recharging, display, programmer, and training domains. Common positive responses were "fewer surgeries" and "small size." Common negative responses were "difficulty finding the right position to recharge" and "need to recharge every day." Hardware-related adverse events occurred in 21 of 59 participants.

CONCLUSION

Patient experience with rechargeable IPGs was largely positive; however, frustrations with recharging and adverse events were common. Dystonia diagnosis was most predictive of high satisfaction across multiple categories, potentially related to expected long disease duration with need for numerous IPG replacements.

Telepsychiatry for patients with movement disorders: a feasibility and patient satisfaction study

Background

Telemedicine is a convenient health service delivery modality for patients with movement disorders, including Parkinson's disease (PD), but is currently underutilized in the management of associated psychiatric symptoms. This study explored the feasibility of and patient satisfaction with telepsychiatry services at an academic movement disorders center.

Methods

All patients seen by telepsychiatry between January and December 2017 at the UCSF Movement Disorders and Neuromodulation Center were invited to participate. Participation was voluntary. Patients received an initial survey after the first telepsychiatry visit and satisfaction surveys after each visit. Survey responses were collected online via Research Electronic Data Capture (REDCap). Frequencies were calculated for categorical variables, and means and standard deviations were generated for continuous variables.

Results

Thirty-three patients (79% with PD; 72% Medicare recipients; 64% men; mean age, 61.1 ± 10.5 years; mean distance to clinic, 79.9 ± 81.3 miles) completed a total of 119 telepsychiatry and 62 in-person visits. Twenty-two initial surveys and 50 satisfaction surveys (from 21 patients) were collected. Patients were very satisfied with the care (95%), convenience (100%), comfort (95%), and overall visit (95%). Technical quality was somewhat lower rated, with 76% patients reporting they were very satisfied, while 19% were satisfied. All patients would recommend telemedicine to friends or family members.

Conclusions

Telepsychiatry is a feasible option for patients with movement disorders, leading to high patient satisfaction and improved access to care. Technical aspects still need optimization. Whenever available, telepsychiatry can be considered in addition to in-person visits. Future studies with larger samples should explore its impact on patient care outcomes and caregiver burden.

Effect of levodopa on electroencephalographic biomarkers of the parkinsonian state

The objective of this study was to evaluate proposed electroencephalographic (EEG) biomarkers of Parkinson's disease (PD) and test their correlation with motor impairment in a new, well-characterized cohort of PD patients and controls. Sixty-four-channel EEG was recorded from 14 patients with rigid-akinetic PD with minimal tremor and from 14 age-matched healthy controls at rest and during voluntary movement. Patients were tested off and on medication during a single session. Recordings were analyzed for phase-amplitude coupling over sensorimotor cortex and for pairwise coherence from all electrode pairs in the recording montage (distributed coherence). Phase-amplitude coupling and distributed coherence were found to be elevated Off compared with On levodopa, and their reduction was correlated with motor improvement. In the Off medication state, phase-amplitude coupling was greater in sensorimotor contacts contralateral to the most affected body part and reduced by voluntary movement. We conclude that phase-amplitude coupling and distributed coherence are cortical biomarkers of the parkinsonian state that are detectable noninvasively and may be useful as objective aids for management of dopaminergic therapy. Several analytic methods may be used for noninvasive measurement of abnormal brain synchronization in PD. Calculation of phase-amplitude coupling requires only a single electrode over motor cortex. NEW & NOTEWORTHY Several EEG biomarkers of the parkinsonian state have been proposed that are related to abnormal cortical synchronization. We report several new findings in this study: correlations of EEG markers of synchronization with specific motor signs of Parkinson's disease (PD), and demonstration that one of the EEG markers, phase-amplitude coupling, is more elevated over the more clinically affected brain hemisphere. These findings underscore the potential utility of scalp EEG for objective, noninvasive monitoring of medication state in PD.

Pallidal thermolesion unleashes gamma oscillations in the motor cortex in Parkinson's disease

BACKGROUND

In Parkinson's disease, the emergence of motor dysfunction is thought to be related to an imbalance between "antikinetic" and "prokinetic" patterns of oscillatory activity in the motor network. Invasive recordings from the basal ganglia and cortex in surgical patients have suggested that levodopa and therapeutic deep brain stimulation can suppress antikinetic beta band (13-30 Hz) rhythms while promoting prokinetic gamma band (60-90 Hz) rhythms. Surgical ablation of the globus pallidus internus is one of the oldest effective therapies for Parkinson's disease and produces remarkably immediate relief of rigidity and bradykinesia, but its effects on oscillatory activity in the motor network have not been studied.

OBJECTIVES

We characterize the effects of pallidotomy on cortical oscillatory activity in Parkinson's patients.

METHODS

Using a temporary 6-contact lead placed over the sensorimotor cortex in the subdural space, we recorded acute changes in cortical oscillatory activities in 3 Parkinson's disease patients undergoing pallidotomy and compared the results to that of 3 essential tremor patients undergoing thalamotomy.

RESULTS

In all 3 Parkinson's disease patients, we observed the emergence of a ~70-80 Hz narrowband oscillation with effective thermolesion of the pallidum. This gamma oscillatory activity was spatially localized over the primary motor cortex, was minimally affected by voluntary movements, and was not found in the motor cortex of essential tremor patients undergoing thalamotomy.

CONCLUSIONS

Our finding suggests that acute lesioning of the pallidum promotes cortical gamma band oscillations. This may represent an important mechanism for alleviating bradykinesia in Parkinson's disease. © 2019 International Parkinson and Movement Disorder Society.

Physiological effects of subthalamic nucleus deep brain stimulation surgery in cervical dystonia

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN DBS) surgery is clinically effective for treatment of cervical dystonia; however, the underlying physiology has not been examined. We used transcranial magnetic stimulation (TMS) to examine the effects of STN DBS on sensorimotor integration, sensorimotor plasticity and motor cortex excitability, which are identified as the key pathophysiological features underlying dystonia.

METHODS

TMS paradigms of short latency afferent inhibition (SAI) and long latency afferent inhibition (LAI) were used to examine the sensorimotor integration. Sensorimotor plasticity was measured with paired associative stimulation paradigm, and motor cortex excitability was examined with short interval intracortical inhibition and intracortical facilitation. DBS was turned off and on to record these measures.

RESULTS

STN DBS modulated SAI and LAI, which correlated well with the acute clinical improvement. While there were no changes seen in the motor cortex excitability, DBS was found to normalise the sensorimotor plasticity; however, there was no clinical correlation.

CONCLUSION

Modulation of sensorimotor integration is a key contributor to clinical improvement with acute stimulation of STN. Since the motor cortex excitability did not change and the change in sensorimotor plasticity did not correlate with clinical improvement, STN DBS demonstrates restricted effects on the underlying physiology.

CLINICAL TRIAL REGISTRATION

NCT01671527.

Adaptive deep brain stimulation for Parkinson's disease using motor cortex sensing

OBJECTIVE

Contemporary deep brain stimulation (DBS) for Parkinson's disease is delivered continuously, and adjustments based on patient's changing symptoms must be made manually by a trained clinician. Patients may be subjected to energy intensive settings at times when they are not needed, possibly resulting in stimulation-induced adverse effects, such as dyskinesia. One solution is 'adaptive' DBS, in which stimulation is modified in real time based on neural signals that co-vary with the severity of motor signs or of stimulation-induced adverse effects. Here we show the feasibility of adaptive DBS using a fully implanted neural prosthesis.

APPROACH

We demonstrate adaptive deep brain stimulation in two patients with Parkinson's disease using a fully implanted neural prosthesis that is enabled to utilize brain sensing to control stimulation amplitude (Activa PC  +  S). We used a cortical narrowband gamma (60-90 Hz) oscillation related to dyskinesia to decrease stimulation voltage when gamma oscillatory activity is high (indicating dyskinesia) and increase stimulation voltage when it is low.

MAIN RESULTS

We demonstrate the feasibility of 'adaptive deep brain stimulation' in two patients with Parkinson's disease. In short term in-clinic testing, energy savings were substantial (38%-45%), and therapeutic efficacy was maintained.

SIGNIFICANCE

This is the first demonstration of adaptive DBS in Parkinson's disease using a fully implanted device and neural sensing. Our approach is distinct from other strategies utilizing basal ganglia signals for feedback control.

Effects of deep brain stimulation on rest tremor progression in early stage Parkinson disease

OBJECTIVE

To evaluate whether the progression of individual motor features was influenced by early deep brain stimulation (DBS), a post hoc analysis of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) score (after a 7-day washout) was conducted from the 2-year DBS in early Parkinson disease (PD) pilot trial dataset.

METHODS

The prospective pilot trial enrolled patients with PD aged 50-75 years, treated with PD medications for 6 months-4 years, and no history of dyskinesia or other motor fluctuations, who were randomized to receive optimal drug therapy (ODT) or DBS plus ODT (DBS + ODT). At baseline and 6, 12, 18, and 24 months, all patients stopped all PD therapy for 1 week (medication and stimulation, if applicable). UPDRS-III "off" item scores were compared between the ODT and DBS + ODT groups (n = 28); items with significant between-group differences were analyzed further.

RESULTS

UPDRS-III "off" rest tremor score change from baseline to 24 months was worse in patients receiving ODT vs DBS + ODT (p = 0.002). Rest tremor slopes from baseline to 24 months favored DBS + ODT both "off" and "on" therapy (p < 0.001, p = 0.003, respectively). More ODT patients developed new rest tremor in previously unaffected limbs than those receiving DBS + ODT (p = 0.001).

CONCLUSIONS

These results suggest the possibility that DBS in early PD may slow rest tremor progression. Future investigation in a larger cohort is needed, and these findings will be tested in the Food and Drug Administration-approved, phase III, pivotal, multicenter clinical trial evaluating DBS in early PD.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with early PD, DBS may slow the progression of rest tremor.

Automated Deep Brain Stimulation Programming for Tremor

Deep brain stimulation (DBS) programming, the systematic selection of fixed electrical stimulation parameters that deliver maximal therapeutic benefit while limiting side effects, poses several challenges in the treatment of movement disorders. DBS programming requires the expertise of trained neurologists or nurses who assess patient symptoms according to standardized clinical rating scales and use patient reports of DBS-related side effects to adjust stimulation parameters and optimize therapy. In this paper, we describe and validate an automated software platform for DBS programming for tremor associated with Parkinson's disease and essential tremor. DBS parameters are changed automatically through a direct computer interface with implanted neurostimulators. Each tested DBS setting is ranked according to its effect on tremor, which is assessed using smartwatch inertial measurement unit data, and side effects, which are reported through a user interface. Blinded neurologist assessments showed the automated programming method performed at least as well as clinician mediated programming in selecting the optimal settings for tremor therapy. This proof of concept study describes a novel DBS programming paradigm that may improve programming efficiency and outcomes, increase access to programming outside specialty clinics, and aid in the development of adaptive and closed-loop DBS strategies.

Cortical gamma oscillations in isolated dystonia

We describe a novel electrophysiologic signal from the motor cortex of patients with generalized dystonia - a discrete gamma-band oscillation induced by movement and associated with emergence of dystonia. This was observed using both invasive and non-invasive methods. This phenomenon is similar to the gamma oscillation reported in parkinsonian dyskinesia.

Chronic deep brain stimulation normalizes scalp EEG activity in isolated dystonia

OBJECTIVE

To investigate cortical activity using scalp EEG in patients with isolated dystonia treated with chronic deep brain stimulation (DBS), on and off stimulation.

METHODS

We analyzed 64-channel scalp EEG in 12 isolated dystonia patients treated with chronic DBS (7 generalized, 5 cervical/segmental; 7 globus pallidus (GP), 5 subthalamic nucleus (STN)), and 20 healthy age-matched controls. Recordings during rest and movement task, and clinical motor scores, were collected with DBS-on and during a 90-min DBS washout.

RESULTS

Resting state alpha power in the dominant (or contralateral to more dystonic side) motor cortex channel during DBS was comparable to healthy controls, but it increased when DBS was stopped. Resting state and movement-related alpha coherence between bilateral motor cortex channels was increased off DBS.

CONCLUSIONS

Chronic DBS reduces exaggerated alpha oscillations and interhemispheric alpha coherence in the motor cortex of patients with isolated dystonia.

SIGNIFICANCE

These findings complement related studies in Parkinson's disease and support the view that network desynchronization is a prominent mechanism of DBS in movement disorders.

Clinical Tremor Severity Estimation Using an Instrumented Eating Utensil

We demonstrate the feasibility of estimating clinical tremor scores using an eating utensil with motion-sensing and tremor-cancellation technology in thirteen patients with tremor. Three experts scored hand tremor using the modified Fahn- Tolosa-Marin (FTM) scale. A linear model was trained to estimate tremor severity using the recorded motion signals. The average neurologist FTM score was 1.6±0.7 for PD and 2.6±0.7 for ET patients. The average model score was 1.6±0.7 for PD and 2.6±0.6 for ET. Correlation coefficient between the clinical and model tremor scores was 0.91 (p < 0.001). Motion data from an instrumented eating utensil accurately derived tremor ratings enabling practical, objective daily monitoring.

Intractable Blepharospasm Treated with Bilateral Pallidal Deep Brain Stimulation

BACKGROUND

Blepharospasm can be present as an isolated dystonia or in conjunction with other forms of cranial dystonia, causing significant disability.

CASE REPORT

We report a case of a 69-year-old male with craniocervical dystonia, manifesting primarily as incapacitating blepharospasm refractory to medical treatments. He underwent bilateral globus pallidus (GP) deep brain stimulation (DBS) with complete resolution of his blepharospasm and sustained benefit at 12 months postoperatively.

DISCUSSION

This case illustrates successful treatment of blepharospasm with pallidal stimulation. GP-DBS should be considered a reasonable therapeutic option for intractable blepharospasm.

Chronic multisite brain recordings from a totally implantable bidirectional neural interface: experience in 5 patients with Parkinson's disease

OBJECTIVE Dysfunction of distributed neural networks underlies many brain disorders. The development of neuromodulation therapies depends on a better understanding of these networks. Invasive human brain recordings have a favorable temporal and spatial resolution for the analysis of network phenomena but have generally been limited to acute intraoperative recording or short-term recording through temporarily externalized leads. Here, the authors describe their initial experience with an investigational, first-generation, totally implantable, bidirectional neural interface that allows both continuous therapeutic stimulation and recording of field potentials at multiple sites in a neural network. METHODS Under a physician-sponsored US Food and Drug Administration investigational device exemption, 5 patients with Parkinson's disease were implanted with the Activa PC+S system (Medtronic Inc.). The device was attached to a quadripolar lead placed in the subdural space over motor cortex, for electrocorticography potential recordings, and to a quadripolar lead in the subthalamic nucleus (STN), for both therapeutic stimulation and recording of local field potentials. Recordings from the brain of each patient were performed at multiple time points over a 1-year period. RESULTS There were no serious surgical complications or interruptions in deep brain stimulation therapy. Signals in both the cortex and the STN were relatively stable over time, despite a gradual increase in electrode impedance. Canonical movement-related changes in specific frequency bands in the motor cortex were identified in most but not all recordings. CONCLUSIONS The acquisition of chronic multisite field potentials in humans is feasible. The device performance characteristics described here may inform the design of the next generation of totally implantable neural interfaces. This research tool provides a platform for translating discoveries in brain network dynamics to improved neurostimulation paradigms. Clinical trial registration no.: NCT01934296 (clinicaltrials.gov).

Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial

INTRODUCTION

This study of thalamic deep brain stimulation (DBS) investigated whether a novel constant-current device improves tremor and activities of daily living (ADL) in patients with essential tremor (ET).

METHODS

A prospective, controlled, multicenter study was conducted at 12 academic centers. We investigated the safety and efficacy of unilateral and bilateral constant-current DBS of the ventralis intermedius (VIM) nucleus of the thalamus in patients with essential tremor whose tremor was inadequately controlled by medications. The primary outcome measure was a rater-blinded assessment of the change in the target limb tremor score in the stimulation-on versus stimulation-off state six months following surgery. Multiple secondary outcomes were assessed at one-year follow-up, including motor, mood, and quality-of-life measures.

RESULTS

127 patients were implanted with VIM DBS. The blinded, primary outcome variable (n = 76) revealed a mean improvement of 1.25 ± 1.26 points in the target limb tremor rating scale (TRS) score in the arm contralateral to DBS (p < 0.001). Secondary outcome variables at one year revealed significant improvements (p ≤ 0.001) in quality of life, depression symptoms, and ADL scores. Forty-seven patients had a second contralateral VIM-DBS, and this group demonstrated reduction in second-sided tremor at 180 days (p < 0.001). Serious adverse events related to the surgery included infection (n = 3), intracranial hemorrhage (n = 3), and device explantation (n = 3).

CONCLUSION

Unilateral and bilateral constant-current VIM DBS significantly improves upper extremity tremor, ADL, quality of life, and depression in patients with severe ET.

Deep brain stimulator implantation in a diagnostic MRI suite: infection history over a 10-year period

OBJECTIVE

The objective of this study was to assess the incidence of postoperative hardware infection following interventional (i)MRI–guided implantation of deep brain stimulation (DBS) electrodes in a diagnostic MRI scanner.

METHODS

A diagnostic 1.5-T MRI scanner was used over a 10-year period to implant DBS electrodes for movement disorders. The MRI suite did not meet operating room standards with respect to airflow and air filtration but was prepared and used with conventional sterile procedures by an experienced surgical team. Deep brain stimulation leads were implanted while the patient was in the magnet, and patients returned 1–3 weeks later to undergo placement of the implantable pulse generator (IPG) and extender wire in a conventional operating room. Surgical site infections requiring the removal of part or all of the DBS system within 6 months of implantation were scored as postoperative hardware infections in a prospective database.

RESULTS

During the 10-year study period, the authors performed 164 iMRI-guided surgical procedures in which 272 electrodes were implanted. Patients ranged in age from 7 to 78 years, and an overall infection rate of 3.6% was found. Bacterial cultures indicated Staphylococcus epidermis (3 cases), methicillin-susceptible Staphylococcus aureus (2 cases), or Propionibacterium sp. (1 case). A change in sterile practice occurred after the first 10 patients, leading to a reduction in the infection rate to 2.6% (4 cases in 154 procedures) over the remainder of the procedures. Of the 4 infections in this patient subset, all occurred at the IPG site.

CONCLUSIONS

Interventional MRI–guided DBS implantation can be performed in a diagnostic MRI suite with an infection risk comparable to that reported for traditional surgical placement techniques provided that sterile procedures, similar to those used in a regular operating room, are practiced.

Subthalamic nucleus deep brain stimulation in isolated dystonia: A 3-year follow-up study

OBJECTIVE

To report long-term safety and efficacy outcomes of a large cohort of patients with medically refractory isolated dystonia treated with subthalamic nucleus (STN) deep brain stimulation (DBS).

METHODS

Twenty patients (12 male, 8 female; mean age 49 ± 16.3 years) with medically refractory isolated dystonia were studied (14 were followed for 36 months). The primary endpoints were change in Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor score and Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score at 36 months compared to preoperative baseline. Multiple secondary outcomes were also assessed (ClinicalTrials.gov NCT00773604).

RESULTS

Eighteen of 20 patients showed improvement 12 months after STN DBS with sustained benefit persisting for 3 years (n = 14). At 36 months, BFMDRS motor scores improved 70.4% from a mean 17.9 ± 8.5 to 5.3 ± 5.6 (p = 0.0002) and total TWSTRS scores improved 66.6% from a mean 41.0 ± 18.9 to 13.7 ± 17.9 (p = 0.0002). Improvement at 36 months was equivalent to that seen at 6 months. Disability and quality of life measures were also improved. Three hardware-related and 24 stimulation-related nonserious adverse events occurred between years 1 and 3 (including 4 patients with dyskinesia).

CONCLUSIONS

This study offers support for long-term tolerability and sustained effectiveness of STN DBS in the treatment of severe forms of isolated dystonia.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that STN DBS decreases long-term dystonia severity in patients with medically refractory isolated dystonia.

Proceedings of the Fourth Annual Deep Brain Stimulation Think Tank: A Review of Emerging Issues and Technologies

This paper provides an overview of current progress in the technological advances and the use of deep brain stimulation (DBS) to treat neurological and neuropsychiatric disorders, as presented by participants of the Fourth Annual DBS Think Tank, which was convened in March 2016 in conjunction with the Center for Movement Disorders and Neurorestoration at the University of Florida, Gainesveille FL, USA. The Think Tank discussions first focused on policy and advocacy in DBS research and clinical practice, formation of registries, and issues involving the use of DBS in the treatment of Tourette Syndrome. Next, advances in the use of neuroimaging and electrochemical markers to enhance DBS specificity were addressed. Updates on ongoing use and developments of DBS for the treatment of Parkinson's disease, essential tremor, Alzheimer's disease, depression, post-traumatic stress disorder, obesity, addiction were presented, and progress toward innovation(s) in closed-loop applications were discussed. Each section of these proceedings provides updates and highlights of new information as presented at this year's international Think Tank, with a view toward current and near future advancement of the field.