A prospective, randomized, blinded assessment of multitarget thalamic and pallidal deep brain stimulation in a case of hemidystonia

Deep brain stimulation for movement disorders after stroke: a systematic review of the literature

OBJECTIVE

Stroke remains the leading cause of disability in the United States. Even as acute care for strokes advances, there are limited options for improving function once the patient reaches the subacute and chronic stages. Identification of new therapeutic approaches is critical. Deep brain stimulation (DBS) holds promise for these patients. A number of case reports and small case series have reported improvement in movement disorders after strokes in patients treated with DBS. In this systematic review, the authors have summarized the patient characteristics, anatomical targets, stimulation parameters, and outcomes of patients who have undergone DBS treatment for poststroke movement disorders.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. The PubMed, Scopus, and SpringerLink databases were searched for the keywords "DBS," "stroke," "movement," and "recovery" to identify patients treated with DBS for movement disorders after a stroke. The Joanna Briggs Institute Critical Appraisal checklists for case reports and case series were used to systematically analyze the quality of the included studies. Data collected from each study included patient demographic characteristics, stroke diagnosis, movement disorder, DBS target, stimulation parameters, complications, and outcomes.

RESULTS

The authors included 29 studies that described 53 patients who underwent placement of 82 total electrodes. Movement disorders included tremor (n = 18), dystonia (n = 18), hemiballism (n = 6), spastic hemiparesis (n = 1), chorea (n = 1), and mixed disorders (n = 9). The most common DBS targets were the globus pallidus internus (n = 32), ventral intermediate nucleus of thalamus (n = 25), and subthalamic area/subthalamic nucleus (n = 7). Monopolar stimulation was reported in 43 leads and bipolar stimulation in 13. High-frequency stimulation was used in 57 leads and low-frequency stimulation in 6. All patients but 1 had improvement in their movement disorders. Two complications were reported: speech impairment in 1 patient and hardware infection in another. The median (interquartile range) duration between stroke and DBS treatment was 6.5 (2.1-15.8) years.

CONCLUSIONS

This is the first systematic review of DBS for poststroke movement disorders. Overall, most studies to date have been case reports and small series reporting heterogeneous patients and surgical strategies. This review suggests that DBS for movement disorders after a stroke has the potential to be effective and safe for diverse patients, and DBS may be a feasible option to improve function even years after a stroke.

Deep brain stimulation for hemidystonia: A meta-analysis with individual patient data

BACKGROUND

Deep brain stimulation (DBS) is now well established for the treatment of dystonic movement disorders. There is limited data, however, on the efficacy of DBS in hemidystonia. This meta-analysis aims to summarize the published reports on DBS for hemidystonia of different etiologies, to compare different stimulation targets, and to evaluate clinical outcome.

METHODS

A systematic literature review was performed on PubMed, Embase and Web of Science to identify appropriate reports. The primary outcome variables were the improvement in the Burke-Fahn-Marsden Dystonia Rating Scale movement (BFMDRS-M) and disability (BFMDRS-D) scores for dystonia.

RESULTS

Twenty-two reports (39 patients; 22 with pallidal stimulation, 4 with subthalamic stimulation, 3 with thalamic stimulation, and 10 with combined target stimulation) were included. Mean age at surgery was 26.8 years. Mean follow-up time was 31.72 months. An overall mean improvement of 40% in the BFMDRS-M score was achieved (range 0%-94%), which was paralleled by a mean improvement of 41% in the BFMDRS-D score. When considering a 20% cut-off for improvement, 23/39 patients (59%) would qualify as responders. Hemidystonia due to anoxia did not significantly improve with DBS. Several limitations of the results must be considered, most importantly the low level of evidence and the small number of reported cases.

CONCLUSION

Based on the results of the current analysis, DBS can be considered as a treatment option for hemidystonia. The posteroventral lateral GPi is the target used most often. More research is needed to understand the variability in outcome and to identify prognostic factors.

A computational study on the optimization of transcranial temporal interfering stimulation with high-definition electrodes using unsupervised neural networks

Transcranial temporal interfering stimulation (tTIS) can focally stimulate deep parts of the brain related to specific functions using beats at two high frequencies that do not individually affect the human brain. However, the complexity and nonlinearity of the simulation limit it in terms of calculation time and optimization precision. We propose a method to quickly optimize the interfering current value of high-definition electrodes, which can finely stimulate the deep part of the brain, using an unsupervised neural network (USNN) for tTIS. We linked a network that generates the values of electrode currents to another network, which is constructed to compute the interference exposure, for optimization by comparing the generated stimulus with the target stimulus. Further, a computational study was conducted using 16 realistic head models. We also compared tTIS with transcranial alternating current stimulation (tACS), in terms of performance and characteristics. The proposed method generated the strongest stimulation at the target, even when targeting deep areas or performing multi-target stimulation. The high-definition tTISl was less affected than tACS by target depth, and mis-stimulation was reduced compared with the case of using two-pair inferential stimulation in deep region. The optimization of the electrode currents for the target stimulus could be performed in 3 min. Using the proposed USNN for tTIS, we demonstrated that the electrode currents of tTIS can be optimized quickly and accurately. Moreover, we confirmed the possibility of precisely stimulating the deep parts of the brain via transcranial electrical stimulation.

New Targets and New Technologies in the Treatment of Parkinson’s Disease: A Narrative Review

Parkinson’s disease (PD) is a progressive neurodegenerative disease, whose main neuropathological finding is pars compacta degeneration due to the accumulation of Lewy bodies and Lewy neurites, and subsequent dopamine depletion. This leads to an increase in the activity of the subthalamic nucleus (STN) and the internal globus pallidus (GPi). Understanding functional anatomy is the key to understanding and developing new targets and new technologies that could potentially improve motor and non-motor symptoms in PD. Currently, the classical targets are insufficient to improve the entire wide spectrum of symptoms in PD (especially non-dopaminergic ones) and none are free of the side effects which are not only associated with the procedure, but with the targets themselves. The objective of this narrative review is to show new targets in DBS surgery as well as new technologies that are under study and have shown promising results to date. The aim is to give an overview of these new targets, as well as their limitations, and describe the current studies in this research field in order to review ongoing research that will probably become effective and routine treatments for PD in the near future.

Subthalamic Nucleus Deep Brain Stimulation in Post-Infarct Dystonia

Dystonia secondary to cerebral infarcts presents months to years after the initial insult, is usually unilateral and causes significant morbidity. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is established as the most frequent target in the management of the dystonic symptoms. We report our experience with subthalamic nucleus (STN) DBS in 3 patients with post-infarct dystonia, in whom GPi DBS was not confidently possible due to the presence of striatal infarcts. Two patients had unilateral STN DBS implantation, whereas the third patient had bilateral STN DBS implantation for bilateral dystonic symptoms. Prospectively collected preoperative and postoperative functional assessment data including imaging, medication and neuropsychology evaluations were analyzed with regard to symptom improvement. Median follow-up period was 38.3 months (range 26–43 months). All patients had clinically valuable improvements in dystonic symptoms and pain control despite variable improvements in the Burke-Fahn-Marsden dystonia rating scores. In our series, we have demonstrated that STN DBS could be an alternative in the management of post-infarct dystonia in patients with abnormal striatal anatomy which precludes GPi DBS. A multidisciplinary team-based approach is essential for patient selection and management.

Multitarget deep brain stimulation for clinically complex movement disorders

Deep brain stimulation (DBS) of single-target nuclei has produced remarkable functional outcomes in a number of movement disorders such as Parkinson's disease, essential tremor, and dystonia. While these benefits are well established, DBS efficacy and strategy for unusual, unclassified movement disorder syndromes is less clear. A strategy of dual pallidal and thalamic electrode placement is a rational approach in such cases where there is profound, medically refractory functional impairment. The authors report a series of such cases: midbrain cavernoma hemorrhage with olivary hypertrophy, spinocerebellar ataxia-like disorder of probable genetic origin, Holmes tremor secondary to brainstem stroke, and hemiballismus due to traumatic thalamic hemorrhage, all treated by dual pallidal and thalamic DBS. All patients demonstrated robust benefit from DBS, maintained in long-term follow-up. This series demonstrates the flexibility and efficacy, but also the limitations, of dual thalamo-pallidal stimulation for managing axial and limb symptoms of tremors, dystonia, chorea, and hemiballismus in patients with complex movement disorders.

Deep brain stimulation for dystonia

BACKGROUND

Dystonia is a painful and disabling disorder, characterised by painful, involuntary posturing of the affected body region(s). Deep brain stimulation is an intervention typically reserved for severe and drug-refractory cases, although uncertainty exists regarding its efficacy, safety, and tolerability.

OBJECTIVES

To compare the efficacy, safety, and tolerability of deep brain stimulation (DBS) versus placebo, sham intervention, or best medical care, including botulinum toxin and resective or lesional surgery, in adults with dystonia.

SEARCH METHODS

We identified studies by searching the CENTRAL, MEDLINE, Embase, three other databases, four clinical trial registries, four grey literature databases, and reference lists of included articles. We ran the last search of all elements of the search strategy, with no language restrictions, on 29 May 2018.

SELECTION CRITERIA

Double-blind, parallel, randomised, controlled trials (RCTs) comparing DBS with sham stimulation, best medical care, or placebo in adults with dystonia.

DATA COLLECTION AND ANALYSIS

Two independent review authors assessed records, selected included studies, extracted data onto a standardised (or prespecified) data extraction form, and evaluated the risk of bias. We resolved disagreements by consensus or by consulting a third review author. We conducted meta-analyses using a random-effects model, to estimate pooled effects and corresponding 95% confidence intervals (95% CI). We assessed the quality of the evidence with GRADE methods. The primary efficacy outcome was symptom improvement on any validated symptomatic rating scale, and the primary safety outcome was adverse events.

MAIN RESULTS

We included two RCTs, enrolling a total of 102 participants. Both trials evaluated the effect of DBS on the internal globus pallidus nucleus, and assessed outcomes after three and six months of stimulation. One of the studies included participants with generalised and segmental dystonia; the other included participants with focal (cervical) dystonia. We assessed both studies at high risk for performance and for-profit bias. One study was retrospectively registered with a clinical trial register, we judged the second at high risk of detection bias.Low-quality evidence suggests that DBS of the internal globus pallidus nucleus may improve overall cervical dystonia-related symptoms (mean difference (MD) 9.8 units, 95% CI 3.52 to 16.08 units; 1 RCT, 59 participants), cervical dystonia-related functional capacity (MD 3.8 units, 95% CI 1.41 to 6.19; 1 RCT, 61 participants), and mood at three months (MD 3.1 units, 95% CI 0.73 to 5.47; 1 RCT, 61 participants).Low-quality evidence suggests that In people with cervical dystonia, DBS may slightly improve the overall clinical status (MD 2.3 units, 95% CI 1.15 to 3.45; 1 RCT, 61 participants). We are uncertain whether DBS improves quality of life in cervical dystonia (MD 3 units, 95% CI -7.71 to 13.71; 1 RCT, 57 participants; very low-quality evidence), or emotional state (MD 2.4 units, 95% CI -6.2 to 11.00; 1 RCT, 56 participants; very low-quality evidence).Low-quality evidence suggests that DBS of the internal globus pallidus nucleus may improve generalised or segmental dystonia-related symptoms (MD 14.4 units, 95% CI 8.0 to 20.8; 1 RCT, 40 participants), overall clinical status (MD 3.5 units, 95% CI 2.33 to 4.67; 1 RCT, 37 participants), physical functioning-related quality of life (MD 6.3 units, 95% CI 1.06 to 11.54; 1 RCT, 33 participants), and overall dystonia-related functional capacity at three months (MD 3.1 units, 95% CI 1.71 to 4.48; 1 RCT, 39 participants). We are uncertain whether DBS improves physical functioning-related quality of life (MD 5.0 units, 95% CI -2.14 to 12.14, 1 RCT, 33 participants; very low-quality evidence), or mental health-related quality of life (MD -4.6 units, 95% CI -11.26 to 2.06; 1 RCT, 30 participants; very low-quality evidence) in generalised or segmental dystonia.We pooled outcomes related to safety and tolerability, since both trials used the same intervention and comparison. We found very low-quality evidence of inconclusive results for risk of adverse events (relative risk (RR) 1.58, 95% 0.98 to 2.54; 2 RCTs, 102 participants), and tolerability (RR 1.86, 95% CI 0.16 to 21.57; 2 RCTs,102 participants).

AUTHORS' CONCLUSIONS

DBS of the internal globus pallidus nucleus may reduce symptom severity and improve functional capacity in adults with cervical, segmental or generalised moderate to severe dystonia (low-quality evidence), and may improve quality of life in adults with generalised or segmental dystonia (low-quality evidence). We are uncertain whether the procedure improves quality of life in cervical dystonia (very low-quality evidence). We are also uncertain about the safety and tolerability of the procedure in adults with either cervical and generalised, or segmental dystonia (very-low quality evidence).We could draw no conclusions for other populations with dystonia (i.e. children and adolescents, and adults with other types of dystonia), or for other DBS protocols (i.e. other target nuclei or stimulation paradigms). Further research is needed to establish the long-term efficacy and safety of DBS of the internal globus pallidus nucleus.

Deep brain stimulation for stroke: Current uses and future directions

BACKGROUND

Survivors of stroke often experience significant disability and impaired quality of life related to ongoing maladaptive responses and persistent neurologic deficits. Novel therapeutic options are urgently needed to augment current approaches. One way to promote recovery and ameliorate symptoms may be to electrically stimulate the surviving brain. Various forms of brain stimulation have been investigated for use in stroke, including deep brain stimulation (DBS).

OBJECTIVE/METHODS

We conducted a comprehensive literature review in order to 1) review the use of DBS to treat post-stroke maladaptive responses including pain, dystonia, dyskinesias, and tremor and 2) assess the use and potential utility of DBS for enhancing plasticity and recovery from post-stroke neurologic deficits.

RESULTS/CONCLUSIONS

A large variety of brain structures have been targeted in post-stroke patients, including motor thalamus, sensory thalamus, basal ganglia nuclei, internal capsule, and periventricular/periaqueductal grey. Overall, the reviewed clinical literature suggests a role for DBS in the management of several post-stroke maladaptive responses. More limited evidence was identified regarding DBS for post-stroke motor deficits, although existing work tentatively suggests DBS-particularly DBS targeting the posterior limb of the internal capsule-may improve paresis in certain circumstances. Substantial future work is required both to establish optimal targets and parameters for treatment of maladapative responses and to further investigate the effectiveness of DBS for post-stroke paresis.

Unilateral thalamic and pallidal deep brain stimulation for idiopathic hemidystonia: results of individual and combined stimulations. Case report

Pallidal stimulation has been the usual surgical treatment for dystonia in the last decades. The continuous investigation of the physiopathology and the motor pathways involved leads to the search for complementary targets to improve results. The authors present the case of a 37-year-old woman who had suffered from idiopathic hemidystonia with hyperkinetic and hypokinetic movements for 11 years, and who was treated with deep brain stimulation. A brief literature review is also provided. The globus pallidus internus and the ventral intermediate/ventral oral posterior complex of the thalamus were stimulated separately and simultaneously for 3 months and compared using the Burke-Fahn-Marsden Dystonia Rating Scale and the Global Dystonia Severity Rating Scale, with a 3.5-year follow-up. The synergism of multiple-target stimulation resulted in a complete improvement of the mixed dystonic symptoms.

The effect of unilateral thalamic deep brain stimulation on the vocal dysfunction in a patient with spasmodic dysphonia: interrogating cerebellar and pallidal neural circuits

Spasmodic dysphonia (SD) is a neurological disorder of the voice where a patient's ability to speak is compromised due to involuntary contractions of the intrinsic laryngeal muscles. Since the 1980s, SD has been treated with botulinum toxin A (BTX) injections into the throat. This therapy is limited by the delayed-onset of benefits, wearing-off effects, and repeated injections required every 3 months. In a patient with essential tremor (ET) and coincident SD, the authors set out to quantify the effects of thalamic deep brain stimulation (DBS) on vocal function while investigating the underlying motor thalamic circuitry. A 79-year-old right-handed woman with ET and coincident adductor SD was referred to our neurosurgical team. While primarily treating her limb tremor, the authors studied the effects of unilateral, thalamic DBS on vocal function using the Unified Spasmodic Dysphonia Rating Scale (USDRS) and voice-related quality of life (VRQOL). Since dystonia is increasingly being considered a multinodal network disorder, an anterior trajectory into the left thalamus was deliberately chosen such that the proximal contacts of the electrode were in the ventral oralis anterior (Voa) nucleus (pallidal outflow) and the distal contacts were in the ventral intermediate (Vim) nucleus (cerebellar outflow). In addition to assessing on/off unilateral thalamic Vim stimulation on voice, the authors experimentally assessed low-voltage unilateral Vim, Voa, or multitarget stimulation in a prospective, randomized, doubled-blinded manner. The evaluators were experienced at rating SD and were familiar with the vocal tremor of ET. A Wilcoxon signed-rank test was used to study the pre- and posttreatment effect of DBS on voice. Unilateral left thalamic Vim stimulation (DBS on) significantly improved SD vocal dysfunction compared with no stimulation (DBS off), as measured by the USDRS (p < 0.01) and VRQOL (p < 0.01). In the experimental interrogation, both low-voltage Vim (p < 0.01) and multitarget Vim + Voa (p < 0.01) stimulation were significantly superior to low-voltage Voa stimulation. For the first time, the effects of high-frequency stimulation of different neural circuits in SD have been quantified. Unexpectedly, focused Voa (pallidal outflow) stimulation was inferior to Vim (cerebellar outflow) stimulation despite the classification of SD as a dystonia. While only a single case, scattered reports exist on the positive effects of thalamic DBS on dysphonia. A Phase 1 pilot trial (DEBUSSY; clinical trial no. NCT02558634, clinicaltrials.gov) is underway at the authors' center to evaluate the safety and preliminary efficacy of DBS in SD. The authors hope that this current report stimulates neurosurgeons to investigate this new indication for DBS.

The "curved lead pathway" method to enable a single lead to reach any two intracranial targets

Deep brain stimulation is an effective way to treat movement disorders, and a powerful research tool for exploring brain functions. This report proposes a “curved lead pathway” method for lead implantation, such that a single lead can reach in sequence to any two intracranial targets. A new type of stereotaxic system for implanting a curved lead to the brain of human/primates was designed, the auxiliary device needed for this method to be used in rat/mouse was fabricated and verified in rat, and the Excel algorithm used for automatically calculating the necessary parameters was implemented. This “curved lead pathway” method of lead implantation may complement the current method, make lead implantation for multiple targets more convenient, and expand the experimental techniques of brain function research.

Clinical and scientific perspectives on movement disorders: Stanley Fahn's contributions

Dr. Stanley Fahn, the H. Houston Merritt Professor of Neurology and Director Emeritus of the Center for Parkinson's Disease and Other Movement Disorders at Columbia University, one of the founders of the field of movement disorders, was the first president of the Movement Disorders Society (subsequently renamed as the International Parkinson and Movement Disorder Society). Together with his friend and colleague, Professor David Marsden, he also served as the first co-editor of the journal Movement Disorders. By emphasizing phenomenology as the key element in differentiating various hypokinetic and hyperkinetic movement disorders, Dr. Fahn drew attention to the clinical history and the power of observation in the diagnosis of movement disorders. Dr. Fahn had major influence on the development of classifications and assessments of various movement disorders and in organizing various research groups such as the Parkinson Study Group. As the founder and president of the World Parkinson Coalition and an organizer of the initial three World Parkinson Congresses, he has demonstrated his long-standing commitment to the cause of including patients as partners. The primary goal and objective of this invited review is to highlight some of Dr. Fahn's most impactful scientific and clinical contributions to the understanding and treatment of Parkinson's disease, dystonia, and other movement disorders.