Deep brain stimulation for dystonia: outcome at long-term follow-up

Optimizing the trajectory of deep brain stimulation leads reduces RF heating during MRI at 3 T: Characteristics and clinical translation

Radiofrequency (RF) induced tissue heating around deep brain stimulation (DBS) leads is a well-known safety risk during magnetic resonance imaging (MRI), hindering routine protocols for patients. Known factors that contribute to variations in the magnitude of RF heating across patients include the implanted lead's trajectory and its orientation with respect to the MRI electric fields. Currently, there are no consistent requirements for surgically implanting the extracranial portion of the DBS lead. Recent studies have shown that incorporating concentric loops in the extracranial trajectory of the lead can reduce RF heating, but the optimal positioning of the loop is unknown. In this study, we evaluated RF heating of 77 unique lead trajectories to determine how different characteristics of the trajectory affect RF heating during MRI at 3 T. We performed phantom experiments with commercial DBS systems from two manufacturers to determine how consistently modifying the lead trajectory mitigates RF heating. We also presented the first surgical implementation of these modified trajectories in patients. Low-heating trajectories included small concentric loops near the surgical burr hole which were readily implemented during the surgical procedure; these trajectories generated nearly a 2-fold reduction in RF heating compared to unmodified trajectories.Clinical Relevance- Surgically modifying the DBS lead trajectory can be a cost-effective strategy for reducing RF-induced heating during MRI at 3 T.

Evaluation of outcome of different neurosurgical modalities in management of cervical dystonia

Background

Cervical dystonia is the most common form of focal dystonia and is managed by multiple modalities including repeated botulinum toxin injections, in addition to medical treatment with anticholinergics, muscle relaxants, and physiotherapy. However, surgical interventions could be beneficial in otherwise refractory patients. This study aims to report our experience in the neurosurgical management of cervical dystonia and evaluate patient outcomes using reliable outcome scores for the assessment of patients with cervical dystonia and possible complications. This case series study was conducted on 19 patients with cervical dystonia of different etiologies who underwent surgical management [ten patients underwent selective peripheral denervation, five patients underwent pallidotomy, and four patients underwent bilateral globus pallidus internus (GPi) deep brain stimulation (DBS)] in the period between July 2018 and June 2021 at Ain Shams University Hospitals, Cairo, Egypt. With the assessment of surgical outcomes using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and the Tsui scale 6 months postoperatively.

Results

Surgical management of patients with cervical dystonia of either primary or secondary etiology was associated with significant improvement in head and neck postures after 6 months without major complications associated with the different surgical procedures. The mean improvement in total TWSTRS and Tsui scores were 51.2% and 64.8%, respectively, compared with preoperative scores, while the mean improvement in the TWSTRS subscales (severity, disability, and pain) were 40.2%, 66.9%, and 58.3%, respectively.

Conclusion

Cervical dystonia patients in whom non-surgical options have failed to alleviate their symptoms can be managed surgically leading to significant improvements with minimal adverse effects. However, surgical treatment should be tailored according to several factors including but not limited to the etiology, pattern of dystonic activity, and comorbidities. Therefore, management should be tailored to achieve long-term improvement with minimal risk of complications.

Long-term efficacy with deep brain stimulation of the globus pallidus internus in cervical dystonia: a retrospective monocentric study

BACKGROUND

Cervical dystonia (CD) is characterized by involuntary contractions of the cervical muscles. Data on long-term effectiveness of deep brain stimulation (DBS) are rare. The aim of this study was to evaluate the longitudinal ten years treatment efficacy of DBS in the globus pallidus internus (GPI).

METHODS

A retrospective single-center data analysis was performed on patients with idiopathic CD, who were treated with GPI DBS for at least 10 years. TWSTR severity score and individual sub-items were compared between pre and post DBS surgery (n = 15) over time.

RESULTS

There was a significant and persistent positive effect regarding the severity of TWSTRS between the conditions immediately before and 1, 5, and 10 years after establishment of GPI DBS (mean difference: 6.6-7 ± 1.6). Patients with increasing CD complexity showed a poorer response to established treatment forms, such as injection of botulinum toxin and were thus DBS candidates. Especially a predominant torticollis was significantly improved by DBS.

CONCLUSION

GPI DBS is an effective procedure especially in severely affected patients with a positive 10-year outcome. It should be considered in more complex CD-forms or predominant torticollis.

Dystonia in veterinary neurology

Dystonia is a clinical sign and main feature of many movement disorders in humans as well as veterinary species. It is characterized by sustained or intermittent involuntary muscle contractions causing abnormal (often repetitive) movements, postures, or both. This review discusses the terminology and definition of dystonia, its phenomenology, and its pathophysiology, and provides considerations regarding the diagnosis and treatment of dystonia in dogs and cats. In addition, currently recognized or reported disorders in dogs and cats in which dystonia is a particular or main feature are discussed and comparisons are made between disorders featuring dystonia in humans and animals. We suggest that when describing the phenomenology of dogs and cats with dystonia, if possible the following should be included: activity being performed at onset (e.g., resting or running or exercise-induced), body distribution, duration, responsiveness (subjective), severity, temporal pattern (i.e., paroxysmal or persistent, severity at onset and at later stages), presence or absence of autonomic signs (e.g., salivation), presence or absence of preceding signs (e.g., restlessness), presence or absence of signs after dystonia subsides (e.g., sleepiness), coexistence of other movement disorders, any other neurological manifestations, and possible links to administered medications, intoxications or other associated factors. We also suggest that dystonia be classified based on its etiology as either structural genetic, suspected genetic, reactive, or unknown.

Outcome of pallidal deep brain stimulation for treating isolated orofacial dystonia

BACKGROUND

Isolated orofacial dystonia is a rare segmental neurological disorder that affects the eye, mouth, face, and jaws. Current literature on pallidal surgery for orofacial dystonia is limited to case reports and small-scale studies. This study was to investigate clinical outcomes of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in patients with isolated orofacial dystonia.

METHODS

Thirty-six patients who underwent GPi DBS at Incheon St. Mary's Hospital, The Catholic University of Korea, between 2014 and 2019 were included in this study. Burke-Fahn-Marsden Dystonia Rating Scale, Unified Dystonia Rating Scale, and Global Dystonia Severity Rating Scale were retrospectively retrieved for analysis before surgery, at 6-month follow-up as short-term outcome, and at follow-up over 1 year (12 months to 69 months) as long-term results.

RESULTS

Mean total BFMDRS-M scores at the three time points (baseline, 6 months, and over 1 year follow-up) were 11.6 ± 4.9, 6.1 ± 5.2 (50.3 ± 29.9% improvement, p < 0.05), and 4.3 ± 4.2 (65.0 ± 24.2% improvement, p < 0.05), respectively. In terms of UDRS and GDS, improvement rates were 45.1% (p < 0.001) and 47.7% (p < 0.001) at 6 months, and 63.8% (p < 0.001) and 65.7% (p < 0.001) at over 1 year after surgery, respectively.

CONCLUSIONS

Bilateral GPi DBS in isolated orofacial dystonia can be effective if conservative treatment option fails. Its benefit is not only observed in a short term, but also maintained in a long-term follow-up.

Bilateral pallidal DBS for blepharospasm: A case report and review of the literature

Background:

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) in the treatment of craniocervical dystonia often requires an extended period of stimulation parameter manipulations.

Case Description:

We present a patient suffering from debilitating blepharospasm treated with bilateral DBS of the GPi alongside 7 years of stimulation parameter manipulations and a literature review of comparable patients.

Conclusion:

Our literature review suggests that a patient’s specific dystonic symptoms can guide stimulation parameter manipulations. Further research regarding trends in stimulation parameters being used in the field for different dystonic symptoms may expedite the stimulation parameter manipulation process.

Disorders of Movement due to Acquired and Traumatic Brain Injury

Purpose of Review

Both traumatic and acquired brain injury can result in diffuse multifocal injury affecting both the pyramidal and extrapyramidal tracts. Thus, these patients may exhibit signs of both upper motor neuron syndrome and movement disorder simultaneously which can further complicate diagnosis and management. We will be discussing movement disorders following acquired and traumatic brain injury.

Recent Findings

Multiple functions including speech, swallowing, posture, mobility, and activities of daily living can all be affected. Medical treatment and rehabilitation-based therapy can be especially challenging due to accompanying cognitive deficits and severity of the disorder which can involve multiple limbs in addition to muscles of the face and axial skeleton. Tremor and dystonia are the most reported movement disorders following traumatic brain injury. Dystonia and myoclonus are well documented following hypoxic ischemic brain injuries. Electrophysiological studies such as dynamic surface poly-electromyography can assist with identifying phenomenology, especially differentiating between jerk-like phenomenon and help guide further work up and management. Management with medications remains challenging due to potential adverse effects. Surgical interventions including stereotactic surgery, deep brain stimulation, and intrathecal baclofen pumps have been reported, but most of the evidence supporting them has been limited to primarily case reports except for post-traumatic tremor.

Summary

Brain injury can lead to motor disorders, movement disorders, visual (processing) deficits, and vestibular deficits which often coexist with cognitive deficits making it challenging to treat and rehabilitate these patients. Unfortunately, the evidence regarding the medical management and rehabilitation of brain injury patients with movement disorders is sparse and leaves much to be desired.

Pain in cervical dystonia: mechanisms, assessment and treatment

INTRODUCTION

In patients with cervical dystonia (CD), pain is a major contributor to disability and social isolation and is often the main reason patients seek treatment. Surveys evaluating patient perceptions of their CD symptoms consistently highlight pain as a troublesome and disabling feature of their condition with significant impact on daily life and work.

AREAS COVERED

In this article, the authors review the epidemiology, assessment, possible mechanisms and treatment of pain in CD, including a meta-analysis of randomized controlled trial data with abobotulinumtoxinA.

EXPERT OPINION

Mechanisms of pain in CD may be muscle-based and non-muscle based. Accumulating evidence suggests that non-muscle-based mechanisms (such as abnormal transmission and processing of nociceptive stimuli, dysfunction of descending pain inhibitory pathways as well as structural and network changes in the basal ganglia, cortex and other areas) may also contribute to pain in CD alongside prolonged muscle contraction. Chemodenervation with botulinum toxin is considered the first-line treatment for CD. Treatment with botulinum toxin is usually effective, but optimization of the injection parameters should include consideration of pain as a core symptom in addition to the motor problems.

Surgical Management for Dystonia: Efficacy of Deep Brain Stimulation in the Long Term

Introduction: Dystonia is a movement disorder substantially affecting the quality of life. Botulinum Neurotoxin (BoNT) is used intramuscularly as a treatment for dystonia; however, not all dystonia patients respond to this treatment. Deep brain stimulation (DBS) is an established treatment for Parkinson’s disease (PD) and essential tremor, but it can help in dystonia as well. Objectives: We studied a total of 67 dystonia patients who were treated with DBS over a period of 7 years to find out the long-term efficacy of DBS in those patients. First, we calculated patient improvement in post-surgery follow-up programs using the Global Dystonia Severity scale (GDS) and Burke–Fahn–Marsden dystonia rating scale (BFMDRS). Secondly, we analyzed the scales scores to see if there was any statistical significance. Methods: In our study we analyzed patients with ages from 38 to 78 years with dystonia who underwent DBS surgery between January 2014 and December 2020 in four different centers (India, Kuwait, Egypt, and Turkey). The motor response to DBS surgery was retrospectively measured for each patient during every follow-up visit using the GDS and the BFMDRS scales. Results: Five to 7 years post-DBS, the mean reduction in the GDS score was 30 ± 1.0 and for the BFMDRS score 26 ± 1.0. The longitudinal change in scores at 12 and 24 months post-op was also significant with mean reductions in GDS and BFMDRS scores of 68 ± 1.0 and 56 ± 1.0, respectively. The p-values were <0.05 for our post-DBS dystonia patients. Conclusions: This study illustrates DBS is an established, effective treatment option for patients with different dystonias, such as generalized, cervical, and various brain pathology-induced dystonias. Although symptoms are not completely eliminated, continuous improvements are noticed throughout the post-stimulation time frame.

Blepharospasm, Oromandibular Dystonia, and Meige Syndrome: Clinical and Genetic Update

Meige syndrome (MS) is cranial dystonia characterized by the combination of upper and lower cranial involvement and including binocular eyelid spasms (blepharospasm; BSP) and involuntary movements of the jaw muscles (oromandibular dystonia; OMD). The etiology and pathogenesis of this disorder of the extrapyramidal system are not well-understood. Neurologic and ophthalmic examinations often reveal no abnormalities, making diagnosis difficult and often resulting in misdiagnosis. A small proportion of patients have a family history of the disease, but to date no causative genes have been identified to date and no cure is available, although botulinum toxin A therapy effectively mitigates the symptoms and deep brain stimulation is gaining increasing attention as a viable alternative treatment option. Here we review the history and progress of research on MS, BSP, and OMD, as well as the etiology, pathology, diagnosis, and treatment.

Bilateral Pallidal Stimulation in a Family With Myoclonus Dystonia Syndrome Due to a Mutation in the Sarcoglycan Gene

OBJECTIVES

The study aimed to present a family with myoclonus dystonia (M-D) syndrome due to a mutation in the epsilon sarcoglycan gene (SGCE). Three members of the family suffered from treatment-refractory severe myoclonic jerks of the neck, trunk, and upper extremities. The mild dystonic symptoms recognized as cervical dystonia or truncal dystonia affected all individuals. The efficacy of pharmacotherapy, including anticholinergic, dopaminergic, and serotoninergic drugs, has failed. One individual developed an alcohol dependency and suffered from alcoholic epilepsy.

MATERIALS AND METHODS

The patients were referred for stereotactic surgery. All individuals underwent bilateral implantation of deep brain stimulation (DBS) leads into the posteroventrolateral segment of the globus pallidus internus (GPi). Surgeries were uneventful. The formal preoperative objective assessment included the Unified Myoclonus Rating Scale (UMRS) and the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). The postoperative UMRS and BFMDRS assessments were done only under continuous stimulation at 3, 6, and 12 months after the surgery and at the last available follow-up ranging from 6 to 15 months (mean, 10 months follow-up).

RESULTS

At the last follow-up visit, the rest and action parts of UMRS were improved by 93.3% and 88.2%, respectively, when compared to the baseline scores. The motor and disability scales of BFMDRS were improved by 77% and 43% at the last follow-up visit compared to the baseline BFMDRS scores. There were no hardware or stimulation-induced complications over the follow-up period. Positive social adjustment allowed two patients to regain jobs and one patient continued his education and hobbies.

CONCLUSION

Our experience gathered in three individuals in the family with a mutation in SGCE indicates that bilateral GPi DBS can be an effective and safe treatment for disabling pharmacological resistant, intractable M-D syndrome.

Deep brain stimulation treatment in dystonia: a bibliometric analysis

BACKGROUND

Dystonia is a heterogeneous disorder that, when refractory to medical treatment, may have a favorable response to deep brain stimulation (DBS). A practical way to have an overview of a research domain is through a bibliometric analysis, as it makes it more accessible for researchers and others outside the field to have an idea of its directions and needs.

OBJECTIVE

To analyze the 100 most cited articles in the use of DBS for dystonia treatment in the last 30 years.

METHODS

The research protocol was performed in June 2019 in Elsevier's Scopus database, by retrieving the most cited articles regarding DBS in dystonia. We analyzed authors, year of publication, country, affiliation, and targets of DBS.

RESULTS

Articles are mainly published in Movement Disorders (19%), Journal of Neurosurgery (9%), and Neurology (9%). European countries offer significant contributions (57% of our sample). France (192.5 citations/paper) and Germany (144.1 citations/paper) have the highest citation rates of all countries. The United States contributes with 31% of the articles, with 129.8 citations/paper. The publications are focused on General outcomes (46%), followed by Long-term outcomes (12.5%), and Complications (11%), and the leading type of dystonia researched is idiopathic or inherited, isolated, segmental or generalized dystonia, with 27% of articles and 204.3 citations/paper.

CONCLUSIONS

DBS in dystonia research is mainly published in a handful of scientific journals and focused on the outcomes of the surgery in idiopathic or inherited, isolated, segmental or generalized dystonia, and with globus pallidus internus as the main DBS target.

Clinical outcomes of pallidal deep brain stimulation for dystonia implanted using intraoperative MRI

OBJECTIVE

Lead placement for deep brain stimulation (DBS) using intraoperative MRI (iMRI) relies solely on real-time intraoperative neuroimaging to guide electrode placement, without microelectrode recording (MER) or electrical stimulation. There is limited information, however, on outcomes after iMRI-guided DBS for dystonia. The authors evaluated clinical outcomes and targeting accuracy in patients with dystonia who underwent lead placement using an iMRI targeting platform.

METHODS

Patients with dystonia undergoing iMRI-guided lead placement in the globus pallidus pars internus (GPi) were identified. Patients with a prior ablative or MER-guided procedure were excluded from clinical outcomes analysis. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores and Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores were assessed preoperatively and at 6 and 12 months postoperatively. Other measures analyzed include lead accuracy, complications/adverse events, and stimulation parameters.

RESULTS

A total of 60 leads were implanted in 30 patients. Stereotactic lead accuracy in the axial plane was 0.93 ± 0.12 mm from the intended target. Nineteen patients (idiopathic focal, n = 7; idiopathic segmental, n = 5; DYT1, n = 1; tardive, n = 2; other secondary, n = 4) were included in clinical outcomes analysis. The mean improvement in BFMDRS score was 51.9% ± 9.7% at 6 months and 63.4% ± 8.0% at 1 year. TWSTRS scores in patients with predominant cervical dystonia (n = 13) improved by 53.3% ± 10.5% at 6 months and 67.6% ± 9.0% at 1 year. Serious complications occurred in 6 patients (20%), involving 8 of 60 implanted leads (13.3%). The rate of serious complications across all patients undergoing iMRI-guided DBS at the authors' institution was further reviewed, including an additional 53 patients undergoing GPi-DBS for Parkinson disease. In this expanded cohort, serious complications occurred in 11 patients (13.3%) involving 15 leads (10.1%).

CONCLUSIONS

Intraoperative MRI-guided lead placement in patients with dystonia showed improvement in clinical outcomes comparable to previously reported results using awake MER-guided lead placement. The accuracy of lead placement was high, and the procedure was well tolerated in the majority of patients. However, a number of patients experienced serious adverse events that were attributable to the introduction of a novel technique into a busy neurosurgical practice, and which led to the revision of protocols, product inserts, and on-site training.

Pallidal Deep Brain Stimulation in Patients with Prior Bilateral Pallidotomy and Selective Peripheral Denervation for Treatment of Dystonia

INTRODUCTION

Deep brain stimulation (DBS) of the globus pallidus internus has become an accepted treatment for severe isolated idiopathic and inherited dystonia. Patients who had other forms of surgery earlier, such as radiofrequency lesioning or selective peripheral denervation, however, usually are not considered candidates for DBS.

OBJECTIVE

The aim of this study was to evaluate the long-term outcome of pallidal DBS in a rare subgroup of patients who had undergone both pallidotomy and selective peripheral denervation previously with a waning effect over the years.

METHODS

Pallidal DBS was performed according to a prospective study protocol in 2 patients with isolated idiopathic dystonia, and patients were followed for a period of at least 6 years.

RESULTS

Both patients benefitted from long-lasting amelioration of dystonia after pallidal DBS, which was comparable to that of patients who did not have previous surgeries. In a 62-year-old female with cervical dystonia both the Burke-Fahn-Marsden (BFM) and the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) motor scores were improved at follow-up 8 years after surgery (50 and 39%). In a 32-year-old male with generalized dystonia, the BFM motor and disability scores showed marked improvement at 6.5 years of follow-up (82 and 66%).

CONCLUSIONS

Pallidal DBS can yield marked and long-lasting improvement in patients who underwent both pallidotomy and selective peripheral denervation earlier. Therefore, such patients, in general, should not be excluded from DBS.

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.

Auditory-Perceptual Evaluation of Deep Brain Stimulation on Voice and Speech in Patients With Dystonia

OBJECTIVE

To determine the effects of globus pallidus interna (GPi) deep brain stimulation (DBS) on speech and voice quality of patients with primary, medically refractory dystonia.

METHODS

Voices of 14 patients aged ≥18 years (males = 7 and females = 7) with primary dystonia (DYT1 gene mutation dystonia = 4, cervical dystonia = 6, and generalized dystonia = 4) with bilateral GPi DBS were assessed. Five blinded raters (two fellowship-trained laryngologists and three speech/language pathologists) evaluated audio recordings of each patient pre- and post-DBS. Perceptual voice quality was rated using the Grade, Roughness, Breathiness, Asthenia, and Strain scale and changes in speech intelligibility were assessed with the Clinical Global Impression scale of Severity instrument. Inter-rater and intrarater reliability rates for perceptual voice ratings were assessed using the kappa coefficient.

RESULTS

Voice quality parameters showed mean improvements in Grade (P < 0.0001), Roughness (P = 0.0043), and Strain (P < 0.0001) 12 months post-DBS. Asthenia increased from baseline to 6 months (P = 0.0022) and declined significantly from 6 to 12 months (P = 0.0170). Breathiness did not change significantly over time. Speech intelligibility also improved from 6 to 12 months (P = 0.0202) and from pre-DBS to 12 months post-DBS (P = 0.0022). Grade and Strain ratings had nearly perfect and substantial inter-rater agreement (0.84 and 0.71, respectively).

CONCLUSIONS

Voice and speech intelligibility improved after bilateral GPi DBS for dystonia. GPi DBS may emerge as a potential treatment option for patients with medically refractory laryngeal dystonia.

Predictive factors of outcome in cervical dystonia following deep brain stimulation: an individual patient data meta-analysis

BACKGROUND

Deep brain stimulation (DBS) therapy has been suggested to be a beneficial alternative in cervical dystonia (CD) for patients who failed nonsurgical treatments. This individual patient data meta-analysis compared the efficacy of DBS in the globus pallidus internus (GPi) versus subthalamic nucleus (STN) and identified possible predictive factors for CD.

METHODS

Three electronic databases (PubMed, Embase and Web of Science) were searched for studies with no publication date restrictions. The primary outcomes were normalized by calculating the relative change in TWSTRS total scores and subscale scores at the last follow-up. Data were analyzed mainly using Pearson's correlation coefficients and a stepwise multivariate regression analysis.

RESULTS

Thirteen studies (86 patients, 58 with GPi-DBS and 28 with STN-DBS) were eligible. Patients showed significant improvement in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) (52.5 ± 11.6 vs 21.9 ± 14.9, P < 0.001) scores at the last follow-up (22.0 ± 14.3 months), compared with scores at baseline, with a mean improvement of 56.6% (P < 0.001) (54.9% in severity, 63.2% in disability, 41.7% in pain). There was no significant difference in the improvement (%) of the total TWSTRS scores in 3 years for the GPI and STN groups (58.1 ± 22.6 vs 47.5 ± 39.2, P > 0.05). Age at surgery and age at symptom onset were negatively correlated with the relative changes in TWSTRS scores at the last follow-up, while there was a positive correlation with preoperative TWSTRS scores. On the stepwise multivariate regression, only the age at surgery remained significant in the best predictive model.

CONCLUSIONS

GPi-DBS and STN-DBS both provided a common great improvement in the symptoms of CD patients in 3 years. Earlier age at surgery may probably indicate larger improvement. More randomized large-scale clinical trials are warranted in the future.

Long-term effects of bilateral pallidal deep brain stimulation in dystonia: a follow-up between 8 and 16 years

Objective

Observational study to evaluate the long-term motor and non-motor effects of deep brain stimulation (DBS) of the globus pallidus internus (GPi) on medically refractory dystonia.

Background

Dystonia is a chronic disease affecting mainly young patients with a regular life expectancy and lifelong need for therapy. Pallidal DBS is an established treatment for severe isolated dystonia but long-term data are sparse.

Methods

We considered 36 consecutive patients with isolated generalized (n = 14) and cervical/segmental (n = 22) dystonia operated at Charité-University Hospital between 2000 and 2007 in a retrospective analysis for long-term outcome of pallidal DBS. In 19 of these patients, we could analyze dystonic symptoms and disability rated by the Burke–Fahn–Marsden Dystonia Rating scale (BFMDRS) at baseline, short-term (ST-FU, range 3–36 months) and long-term follow-up (LT-FU, range 93–197 months). Quality of life and mood were evaluated using the SF36 and Beck Depression Index (BDI) questionnaires.

Results

Patients reached an improvement in motor symptoms of 63.8 ± 5.7% (mean ± SE) at ST-FU and 67.9 ± 6.1% at LT-FU. Moreover, a significant and stable reduction in disability was shown following DBS (54.2 ± 9.4% at ST-FU and 53.8 ± 9.2% at LT-FU). BDI and SF36 had improved by 40% and 23%, respectively, at LT-FU (n = 14). Stimulation-induced adverse events included swallowing difficulties, dysarthria, and bradykinesia. Pulse generator (n = 3) and electrodes (n = 5) were revised in seven patients due to infection.

Conclusions

Pallidal DBS is a safe and efficacious long-term treatment for dystonia with sustained effects on motor impairment and disability, accompanied by a robust improvement in mood and quality of life.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-09745-z) contains supplementary material, which is available to authorized users.

Deep brain stimulation for Meige syndrome: a meta-analysis with individual patient data

BACKGROUND

Deep brain stimulation (DBS) is an effective intervention for Meige syndrome, a type of dystonia characterized by blepharospasm, facial, and oromandibular dystonia. This individual patient-level data meta-analysis was to identify the potential outcome predictors, compare the stimulation targets and summarize the efficacy of DBS for Meige syndrome.

METHODS

Three electronic databases (PubMed, Web of Science and Embase) were searched with no publication data restriction to identify studies regarding DBS for Meige syndrome. The primary outcome was the improvement in BFMDRS-M score. Pearson's correlation coefficients and a stepwise multivariate regression analysis were used to identify the potential prognostic factors.

RESULTS

Twenty-three studies (115 patients, 94 with pallidal stimulation and 21 with subthalamic stimulation) were eligible. Patients showed significant improvement in Burke-Fahn-Marsden Dystonia Rating Scale movement (BFMDRS-M) (21.5 ± 11.0 vs 8.6 ± 6.9, P < 0.001) and disability (BFMDRS-D) (6.4 ± 5.1 vs 2.9 ± 2.4, P < 0.001) scores at the last follow-up visit (31.9 ± 30.7 months), compared with scores at baseline. Preoperative BFMDRS-M and BFMDRS-D scores were positively correlated with the relative changes in BFMDRS-M score at the last follow-up visit. On the stepwise multivariate regression, only the preoperative BFMDRS remained significant in the best predictive model.

CONCLUSIONS

Based on the existing evidence, pallidal/subthalamic stimulation is an effective therapy for even the refractory Meige syndrome. Higher preoperative scores probably indicate larger improvement. Stimulation targets or other clinical factors do not constitute the outcome predictive factors.

Deep brain stimulation for dystonia in Finland during 2007-2016

BACKGROUND

Dystonia is a movement disorder substantially affecting the quality of life and the ability to work. A proportion of patients does not respond to first line pharmacotherapy. Deep brain stimulation (DBS) is established as a primary operative treatment option for severe drug resistant dystonia. We studied dystonia patients treated with DBS in Finland between the years 2007-2016 to evaluate the use and outcomes of DBS treatment.

METHODS

We analysed the hospital records of dystonia patients, who underwent DBS operation during 2007-2016 in Finland. The clinical and technical parameters were recorded as well as preoperative assessments and treatments. The response to DBS was evaluated retrospectively using the Global Dystonia Rating Scale (GDS).

RESULTS

Out of 585 dB implantations during the study period, 37 were done for dystonia. The clinical response improved significantly with time in the isolated focal dystonia group, and at 12 months, 22 of 32 patients had over 50% alleviation of the GDS score. There was only one subclinical intracerebral haemorrhage, and four infections leading to revision. Speech impairment and limb coordination problems were common stimulation- related adverse events and were mostly resolved or relieved with the adjustment of stimulation parameters.

CONCLUSIONS

DBS seems to be beneficial in dystonia. Although DBS is indicated for dystonia in Finland, the number of operations did not increase at the same rate as DBS operations in general. DBS appears to be a safe and effective treatment for focal as well as generalized dystonia.

Patient-adjusted deep-brain stimulation programming is time saving in dystonia patients

BACKGROUND

Deep-brain stimulation (DBS) programming for dystonia patients is a complex and time-consuming task.

OBJECTIVE

To analyze whether programming a programming paradigm based on patient's self-adjustment is practical, effective and time saving in dystonia.

METHODS

We retrospectively compared dystonia rating scales as well as the time necessary to optimize programming and the number of in-hospital visits in all patients (n = 102) operated at our center who used simple mode (SM) or advanced mode (AM) programming; the latter uses groups of different stimulation parameters and allows the patient and their caregiver to change stimulation groups at home, using the patient remote control.

RESULTS

Both AM- and SM-allocated patients improved clinically to the same extent after DBS, as assessed by the Burke-Fahn-Marsden (BFM) and the Toronto Western Spasmodic Torticollis (TWSTRS) dystonia rating scales. All subscores improved after DBS without statistically significant differences in improvement between AM and SM (BFM: - 43% vs. - 53%, p = 0.569; TWSTRS: - 63% vs. - 72%, p = 0.781). AM and SM patients reached optimization within a similar median time [5.5 months (95% CI 4.6-6.3) for AM vs. 6.2 months (4.2-7.6) for SM, p = 0.674) but patients on advanced programming needed fewer in-hospital visits to achieve the same improvement [median of 5 visits (95% CI 4-7) for AM vs. 8 visits (7-9) for SM, p = 0.008].

CONCLUSIONS

Advanced DBS programming based on patient's self-adjustment under the supervision of the treating physician is feasible, practical and significantly reduces consultation time in dystonia patients.

Case Report: Targeting for Deep Brain Stimulation Surgery Using Chronic Recording and Stimulation in an Inpatient Neuromodulation Monitoring Unit, With Implantation of Electrodes in GPi and Vim in a 7-Year-Old Child With Progressive Generalized Dystonia

BACKGROUND

Deep brain stimulation for secondary dystonia has been limited by unknown optimal targets for individual children.

OBJECTIVES

We report the first case of a 7-year-old girl with severe generalized dystonia due to acquired striatal necrosis in whom we used a new method for identifying targets for deep brain stimulation.

METHODS

We implanted temporary depth electrodes in 5 different nuclei bilaterally in the basal ganglia and thalamus, with test stimulation and recording during 1 week while the child was an inpatient in a neuromodulation monitoring unit.

RESULTS

Single-unit activity in ventral intermedius Vim, internal globus pallidus (GPi), and subthalamic (STN) nuclei occurred during dystonic spasms and correlated with electromyography. Stimulation in Vim eliminated dystonic spasms. Subsequent implantation of 4 permanent deep brain stimulation electrodes in bilateral Vim and Gpi nuclei resolved dystonic spasms.

CONCLUSION

The use of temporary stimulation and recording electrodes to identify deep brain stimulation targets is a promising new technique that could improve outcomes in children with acquired dystonia.

Surgical treatment of dystonia

INTRODUCTION

Treatment of dystonia should be individualized and tailored to the specific needs of patients. Surgical treatment is an important option in medically refractory cases. Several issues regarding type of the surgical intervention, targets, and predict factors of benefit are still under debate. Areas covered: To date, several clinical trials have proven the benefit and safety of deep brain stimulation (DBS) for inherited and idiopathic isolated dystonia, whereas there is still insufficient evidence in combined and acquired dystonia. The globus pallidus internus (GPi) is the target with the best evidence, but data on the subthalamic nucleus seems also to be promising. Evidence suggests that younger patients with shorter disease duration experience greater benefit following DBS. Pallidotomy and thalamotomy are currently used in subset of carefully selected patients. The development of MRI-guided focused ultrasound might bring new options to ablation approach in dystonia. Expert commentary: GPi-DBS is effective and safe in isolated dystonia and should not be delayed when symptoms compromise quality of life and functionality. Identifying the best candidates to surgery on acquired and combined dystonias is still necessary. New insights about pathophysiology of dystonia and new technological advances will undoubtedly help to tailor surgery and optimize clinical effects.

Bilateral pallidotomy for Meige syndrome

Meige syndrome (MS) is usually described as a combination of blepharospasm with oromandibular dystonia. There are a large number of case reports of deep brain stimulation (DBS) of the globus pallidus internus (GPI) for MS and only one report of unilateral pallidotomy (PT). We report the first case of staged bilateral PT for treatment of a patient with MS using intraoperative high-frequency stimulation in order to predict and prevent postoperative deficit. There was a significant improvement of the Burk-Fahn-Marsden dystonia rating scale from 26 to 3. There were no adverse postoperative neurological and neuropsychological events.

Blepharospasm 40 years later

Forty years ago, C.D. Marsden proposed that blepharospasm should be considered a form of adult-onset focal dystonia. In the present paper, we provide a comprehensive overview of the findings regarding blepharospasm reported in the past 40 years. Although prolonged spasms of the orbicularis oculi muscles remain the clinical hallmark of blepharospasm, patients with blepharospasm may be characterized by various types of involuntary activation of periocular muscles. In addition to motor features, blepharospasm patients may also have nonmotor manifestations, including psychiatric, mild cognitive, and sensory disturbances. The various motor and nonmotor symptoms are not present in all patients, suggesting that blepharospasm is phenomenologically a heterogeneous condition. This emphasizes the need for tools for severity assessment that take into account both motor and nonmotor manifestations. The cause of blepharospasm remains elusive, but several lines of evidence indicate that blepharospasm is a multifactorial condition in which one, or several, as yet unknown genes together with epigenetic and environmental factors combine to reach the threshold of the disease. Although blepharospasm was originally believed to be solely a basal ganglia disorder, neurophysiological and neuroimaging evidence point to anatomical and functional involvement of several brain regions. The contribution of multiple areas has led to the hypothesis that blepharospasm should be considered as a network disorder, and this might reflect the varying occurrence of motor and nonmotor manifestations in blepharospasm patients. Despite advances in the aetiology and pathophysiology, treatment remains symptomatic. © 2017 International Parkinson and Movement Disorder Society.

Pallidal stimulation for medically intractable blepharospasm

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an established procedure to improve generalised, segmental craniofacial dystonia. However, no studies have addressed the applicability of DBS for blepharospasm as a focal craniofacial dystonia. A 52-year-old man developed medically intractable involuntary eye closure. Because the abnormal movement was observed exclusively in the eyelids, he was diagnosed not with Meige's syndrome but with blepharospasm as a focal craniofacial dystonia. He underwent stereotactic surgery under general anaesthesia for bilateral GPi-DBS. Continuous GPi stimulation almost completely abolished the blepharospasm. 15 months after the operation, his preoperative scores on the Burke-Fahn-Marsden Dystonia Rating Scale (=8 points) decreased to 1 (87.5% improvement). The present study demonstrates the applicability of GPi-DBS for treating blepharospasm presenting as focal dystonia. Further studies with accumulated case series are needed to confirm the effect of DBS on blepharospasm and other focal craniofacial dystonias.

Long-Term Clinical Outcome of Internal Globus Pallidus Deep Brain Stimulation for Dystonia

Background

GPi (Internal globus pallidus) DBS (deep brain stimulation) is recognized as a safe, reliable, reversible and adjustable treatment in patients with medically refractory dystonia.

Objectives

This report describes the long-term clinical outcome of 36 patients implanted with GPi DBS at the Neurosurgery Department of Seoul National University Hospital.

Methods

Nine patients with a known genetic cause, 12 patients with acquired dystonia, and 15 patients with isolated dystonia without a known genetic cause were included. When categorized by phenomenology, 29 patients had generalized, 5 patients had segmental, and 2 patients had multifocal dystonia. Patients were assessed preoperatively and at defined follow-up examinations postoperatively, using the Burke-Fahn-Marsden dystonia rating scale (BFMDRS) for movement and functional disability assessment. The mean follow-up duration was 47 months (range, 12–84)

Results

The mean movement scores significantly decreased from 44.88 points preoperatively to 26.45 points at 60-month follow up (N = 19, P = 0.006). The mean disability score was also decreased over time, from 11.54 points preoperatively to 8.26 points at 60-month follow up, despite no statistical significance (N = 19, P = 0.073). When analyzed the movement and disability improvement rates at 12-month follow up point, no significant difference was noted according to etiology, disease duration, age at surgery, age of onset, and phenomenology. However, the patients with DYT-1 dystonia and isolated dystonia without a known genetic cause showed marked improvement.

Conclusions

GPi DBS is a safe and efficient therapeutic method for treatment of dystonia patients to improve both movement and disability. However, this study has some limitations caused by the retrospective design with small sample size in a single-center.

Selective peripheral denervation for cervical dystonia: long-term follow-up

OBJECTIVE

61 procedures with selective peripheral denervation for cervical dystonia were retrospectively analysed concerning surgical results, pain, quality of life (QoL) and recurrences.

METHODS

The patients were assessed with the Tsui torticollis scale, Visual Analogue Scale (VAS) for pain and Fugl-Meyer scale for QoL. Evaluations were performed preoperatively, early postoperatively, at 6 months, then at a mean of 42 (13-165) months. All patients underwent electromyogram at baseline, which was repeated in cases who presented with recurrence of symptoms after surgery.

RESULTS

Six months of follow-up was available for 55 (90%) of the procedures and late follow-up for 34 (56%). The mean score of the Tsui scale was 10 preoperatively. It improved to 4.5 (p<0.001) at 6 months, and 5.3 (p<0.001) at late follow-up. VAS for pain improved from 6.5 preoperatively to 4.2 (p<0.001) at 6 months and 4 (p<0.01) at late follow-up. The Fugl-Meyer score for QoL improved from 43.3 to 46.6 (p<0.05) at 6 months, and to 51.1 (p<0.05) at late follow-up. Major reinnervation and/or change in the dystonic pattern occurred following 29% of the procedures, and led in 26% of patients to reoperation with either additional denervation or pallidal stimulation.

CONCLUSIONS

Selective peripheral denervation remains a surgical option in the treatment of cervical dystonia when conservative measures fail. Although the majority of patients experience a significant relief of symptoms, there is a substantial risk of reinnervation and/or change in the pattern of the cervical dystonia.

Modulation of Muscle Tone and Sympathovagal Balance in Cervical Dystonia Using Percutaneous Stimulation of the Auricular Vagus Nerve

Primary cervical dystonia is characterized by abnormal, involuntary, and sustained contractions of cervical muscles. Current ways of treatment focus on alleviating symptomatic muscle activity. Besides pharmacological treatment, in severe cases patients may receive neuromodulative intervention such as deep brain stimulation. However, these (highly invasive) methods have some major drawbacks. For the first time, percutaneous auricular vagus nerve stimulation (pVNS) was applied in a single case of primary cervical dystonia. Auricular vagus nerve stimulation was already shown to modulate the (autonomous) sympathovagal balance of the body and proved to be an effective treatment in acute and chronic pain, epilepsy, as well as major depression. pVNS effects on cervical dystonia may be hypothesized to rely upon: (i) the alteration of sensory input to the brain, which affects structures involved in the genesis of motoric and nonmotoric dystonic symptoms; and (ii) the alteration of the sympathovagal balance with a sustained impact on involuntary movement control, pain, quality of sleep, and general well-being. The presented data provide experimental evidence that pVNS may be a new alternative and minimally invasive treatment in primary cervical dystonia. One female patient (age 50 years) suffering from therapy refractory cervical dystonia was treated with pVNS over 20 months. Significant improvement in muscle pain, dystonic symptoms, and autonomic regulation as well as a subjective improvement in motility, sleep, and mood were achieved. A subjective improvement in pain recorded by visual analog scale ratings (0-10) was observed from 5.42 to 3.92 (medians). Muscle tone of the mainly affected left and right trapezius muscle in supine position was favorably reduced by about 96%. Significant reduction of muscle tone was also achieved in sitting and standing positions of the patient. Habituation to stimulation leading to reduced stimulation efficiency was observed and counteracted by varying stimulation patterns. Experimental evidence is provided for significantly varied sympathovagal modulation in response to pVNS during sleep, assessed via heart rate variability (HRV). Time domain measures like the root mean square of successive normal to normal heart beat intervals, representing parasympathetic (vagal) activity, increased from 37.8 to 67.6 ms (medians). Spectral domain measures of HRV also show a shift to a more pronounced parasympathetic activity.

Postoperative MRI localisation of electrodes and clinical efficacy of pallidal deep brain stimulation in cervical dystonia

INTRODUCTION

Pallidal deep brain stimulation (DBS) has been shown to be effective in cervical dystonia (CD) with an improvement of about 50-60% in the Toronto Western Spasmodic Torticollis Rating (TWSTR) Scale. However, predictive factors for the efficacy of DBS in CD are missing with the anatomical location of the electrodes being one of the most important potential predictive factors.

METHODS

In the present blinded observational study we correlated the anatomical localisation of DBS contacts with the relative clinical improvement (CI %) in the TWSTR as achieved by DBS at different pallidal contacts in 20 patients with CD. Localisations of DBS contacts were derived from postoperative MRI-data following anatomical normalisation into the standard Montreal Neurological Institute stereotactic space. The CIs following 76 bilateral test stimulations of 24 h were mapped to stereotactic coordinates of the corresponding bilateral 152 active contacts and were allocated to low CI (<30%; n=74), intermediate CI (≥30%; <60%; n=52) or high CI (≥60%; n=26).

RESULTS

Euclidean distances between contacts and the centroid differed between the three clusters (p<0.001) indicating different anatomical variances between clusters. The Euclidean distances between contacts and the centroid of the cluster with high CIs correlated with the individual level of CIs (r=-0.61; p<0.0001). This relationship was best fitted with an exponential regression curve (r(2)=0.41).

DISCUSSION

Our data show that the clinical effect of pallidal DBS on CD displays an exponential decay over anatomical distance from an optimised target localisation within a subregion of the internal pallidum. The results will allow a comparison of future DBS studies with postoperative MRI by verifying optimised (for instance pallidal) targeting in DBS-treated patients.

Childhood dystonias

OPINION STATEMENT

Dystonia is a movement disorder caused by diverse etiologies. Its treatment in children is particularly challenging due to the complexity of the development of the nervous system from birth to young adulthood. The treatment options of childhood dystonia include several oral pharmaceutical agents, botulinum toxin injections, and deep brain stimulation (DBS) therapy. The choice of drug therapy relies on the suspected etiology of the dystonia and the adverse effect profile of the drugs. Dystonic syndromes with known etiologies may require specific interventions, but most dystonias are treated by trying serially a handful of medications starting with those with the best risk/benefit profile. In conjunction to drug therapy, botulinum toxin injections may be used to target a problematic group dystonic muscles. The maximal botulinum toxin dose is limited by the weight of the child, therefore limiting the number of the muscles amenable to such treatment. When drugs and botulinum toxin injections fail to control the child's disabling dystonia, DBS therapy may be offered as a last remedy. Delivering optimal DBS therapy to children with dystonia requires a multidisciplinary team of experienced pediatric neurosurgeons, neurologists, and nurses to select adequate candidates, perform this delicate stereotactic procedure, and optimize DBS delivery. Even in the best hands, the response of childhood dystonia to DBS therapy varies greatly. Future therapy of childhood dystonia will parallel the advancement of knowledge of the pathophysiology of dystonic syndromes and the development of clinical and research tools for their study.

Movement disorders secondary to craniocerebral trauma

Over the past few decades it has been recognized that traumatic brain injury may result in various movement disorders. In survivors of severe head injury, post-traumatic movement disorders were reported in about 20%, and they persisted in about 10% of patients. The most frequent persisting movement disorder in this population is kinetic cerebellar outflow tremor in about 9%, followed by dystonia in about 4%. While tremor is associated most frequently with cerebellar or mesencephalic lesions, patients with dystonia frequently have basal ganglia or thalamic lesions. Moderate or mild traumatic brain injury only rarely causes persistent post-traumatic movement disorders. It appears that the frequency of post-traumatic movement disorders overall has been declining which most likely is secondary to improved treatment of brain injury. In patients with disabling post-traumatic movement disorders which are refractory to medical treatment, stereotactic neurosurgery can provide long-lasting benefit. While in the past the primary option for severe kinetic tremor was thalamotomy and for dystonia thalamotomy or pallidotomy, today deep brain stimulation has become the preferred treatment. Parkinsonism is a rare consequence of single head injury, but repeated head injury such as seen in boxing can result in chronic encephalopathy with parkinsonian features. While there is still controversy whether or not head injury is a risk factor for the development of Parkinson's disease, recent studies indicate that genetic susceptibility might be relevant.

What's new in surgical treatment for dystonia?

It is now established that pallidal deep brain stimulation (DBS) is effective in the treatment of generalized and segmental primary dystonia, although there is still insufficient evidence to support its benefit in focal and secondary dystonia. Because several studies have demonstrated that pallidal DBS improves quality of life (QoL), reduced QoL and disability that are nonresponsive to medical treatment are probably the main factors guiding the decision to consider surgery. Some studies have indicated that young patients with primary dystonia who have shorter disease duration and less severe dystonia are likely to have the best outcome from DBS. Therefore, surgery should not be delayed when disability and QoL are impaired to the extent that justifies the surgical risk. A case-by-case approach is recommended in patients who have secondary dystonia. The globus pallidus internus is considered the best target for dystonia. There are still not enough data about the effectiveness of thalamic, subthalamic nucleus, and premotor cortex stimulation. Targeting with multiple electrodes and intra-individual comparisons of outcomes may help determine which target would be more beneficial. With regard to the role of lesions, pallidotomy for dystonia is still performed in several countries and can play a role in selected patients. New technologies are already available to improve the stimulation programming for DBS patients and to increase battery longevity. In the near future, it is possible that we will be able to shape stimulation settings according to disease type and symptoms. © 2013 Movement Disorder Society.

Deep brain stimulation in DYT1 dystonia: a 10-year experience

BACKGROUND

Globus Pallidus Interna (GPi) deep brain stimulation (DBS) is an effective treatment for DYT1-associated dystonia, but long-term results are lacking.

OBJECTIVE

To evaluate the long-term effects of GPi DBS in patients with DYT1 dystonia.

METHODS

A retrospective chart review (cohort study) of 47 consecutive DYT1+ patients treated by a single surgical team over a 10-year period and followed for up to 96 months (mean, 46 months) was performed. Symptom severity was quantified with the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor (M) and disability (D) sub-scores.

RESULTS

As measured with the BFMDRS (M), symptom severity was reduced to less than 20% of baseline after 2 years of DBS therapy (P = .001). The disability scores were reduced to <30% of baseline (P = .001). Symptomatic improvement was durable throughout available follow-up. Sixty-one percent of patients had discontinued all dystonia-related medications at their last follow-up. Ninety-one percent had discontinued at least 1 class of medication. Infections requiring removal and later reimplantation of hardware occurred in 4 of 47 patients (8.5%). Hardware malfunction including lead fractures occurred in 4 of 47 cases (8.5%). Lead revision to address poor clinical response was performed in 2 of 92 implanted leads (2.2%).

CONCLUSION

GPi DBS is an effective therapy for DYT1-associated torsion dystonia. Statistically significant efficacy is maintained for up to 7 years. Neurologic complications are rare, but long-term hardware-related complications can be significant.

Deep-brain stimulation for dystonia: current indications and future orientations

ABSTRACT: Deep-brain stimulation of the internal globus pallidus is a therapeutic option for dystonia. However, the available data are heterogeneous, ranging from single case reports to a few controlled studies. The outcomes are also largely heterogeneous, depending mostly on the etiology of the dystonia. Except for some well-established good indications, such as primary generalized dystonia and tardive dyskinesia, the efficacy of globus pallidus stimulation remains debated for several forms of dystonia. In addition, many issues are still unsolved, such as the best target of stimulation and the interest of simultaneously combining multiple targets of stimulation or not. Finally the efficacy of new strategies of treatment, such as cortical stimulation, remains to be determined. The aim of this review is to cover these different aspects and give an overview of the current indications and future orientations.

Onset latency of segmental dystonia after deep brain stimulation cessation: a randomized, double-blind crossover trial

BACKGROUND

Deep brain stimulation (DBS) of the globus pallidus internus is an effective treatment for cervical dystonia (CD). Interestingly, the onset of initial DBS effects is significantly prolonged compared with that in other diseases, such as Parkinson's disease. The return of symptoms after cessation of DBS could be delayed as well, but this has not been studied systematically.

METHODS

In patients who were treated for CD using DBS and had a good treatment effect, we compared interruption of DBS with sham-OFF in a randomized, double-blind crossover trial.

RESULTS

We observed that dystonic features appeared within a few minutes at almost full intensity in all patients after the cessation of DBS.

CONCLUSIONS

The almost immediate onset of dystonic features in our sample seems to exclude mechanisms with long time constants from the pathophysiology of dystonia. Thus, it is likely that, in these patients, an aberrant pattern of neural activity representing an inappropriate set point value for the position of the head is responsible for dystonia.

Pallidal deep brain stimulation for dystonia: a case series

OBJECT

Pallidal deep brain stimulation (DBS) is a treatment option for those with early-onset dystonia. However, there are limited data on long-term outcome and treatment complications. The authors report on the short- and long-term effects of pallidal DBS in a cohort of patients with early-onset dystonia.

METHODS

Fourteen consecutive pediatric patients with early-onset dystonia were systematically evaluated and treated. The duration of follow-up ranged from 16 to 84 months.

RESULTS

There were no immediate postoperative complications. At last follow-up, 12 of the 14 patients displayed a significant decline in the Burke-Fahn-Marsden Dystonia Rating Scale motor subscale score, with an average decrease of 62% ± 8.4%. The most common hardware complication was lead fracture (14.3%).

CONCLUSIONS

These data provide further evidence that DBS is a safe and effective treatment for those with earlyonset dystonia.

Deep brain stimulation for dystonia

The few controlled studies that have been carried out have shown that bilateral internal globus pallidum stimulation is a safe and long-term effective treatment for hyperkinetic disorders. However, most recent published data on deep brain stimulation (DBS) for dystonia, applied to different targets and patients, are still mainly from uncontrolled case reports (especially for secondary dystonia). This precludes clear determination of the efficacy of this procedure and the choice of the 'good' target for the 'good' patient. We performed a literature analysis on DBS for dystonia according to the expected outcome. We separated those with good evidence of favourable outcome from those with less predictable outcome. In the former group, we review the main results for primary dystonia (generalised/focal) and highlight recent data on myoclonus-dystonia and tardive dystonia (as they share, with primary dystonia, a marked beneficial effect from pallidal stimulation with good risk/benefit ratio). In the latter group, poor or variable results have been obtained for secondary dystonia (with a focus on heredodegenerative and metabolic disorders). From this overview, the main results and limits for each subgroup of patients that may help in the selection of dystonic patients who will benefit from DBS are discussed.