The antisaccadic paradigm: A complementary neuropsychological tool in basal ganglia disorders

This review explores the role of the antisaccadic task in understanding inhibitory mechanisms in basal ganglia disorders. It conducts a comparative analysis of saccadic profiles in conditions such as Parkinson's disease, Tourette syndrome, obsessive-compulsive disorder, Huntington's disease, and dystonia, revealing distinct patterns and proposing mechanisms for impaired performance. The primary focus is on two inhibitory mechanisms: global, pre-emptive inhibition responsible for suppressing prepotent responses, and slower, selective response inhibition. The antisaccadic task demonstrates practicality in clinical applications, aiding in differential diagnoses, treatment monitoring and reflecting gait control. To further enhance its differential diagnostic value, future directions should address issues such as the standardization of eye-tracking protocol and the integration of eye-tracking data with other disease indicators in a comprehensive dataset.

Quality of life outcomes after deep brain stimulation in acquired dystonia: a systematic review and meta-analysis

BACKGROUND

Dystonia is a condition that affects the ability to control the movement and function of the body's muscles. It can cause not only physical problems, but also mental problems, resulting in impaired health-related quality of life (HRQoL). However, the effect of deep brain stimulation on quality of life in acquired dystonia remains unclear.

METHODS

We conducted a systematic literature review from January 2000 to October 2022，determined the eligible studies, and performed a meta-analysis of HRQoL outcomes based on the Short-Form Health Survey-36 (SF-36) after DBS to evaluate the effects of DBS on physical and mental QoL.

RESULTS

A total of 14 studies met the inclusion criteria and were systematically reviewed. A comprehensive meta-analysis was performed for 9 studies that reported physical and psychological data or physical component summary (PCS), or mental component summary (MCS) for SF-36. The mean (SD) age at DBS implantation was 34.29 (10.3) years, and the follow-up period after implantation was 2.21 (2.80) years. The random effects model meta-analysis revealed that both physical and mental domains of the SF-36 improved following DBS. There was no statistically significant difference between the physical domains (effect size=1.34; p<0.0001) and the mental domains (effect size=1.38; p<0.0001).

CONCLUSION

This is the first meta-analysis that demonstrates significant benefits in HRQoL following DBS in patients with acquired dystonia. There were significant improvements in both physical QoL and mental QoL.

PAllidal versus SubThalamic deep brain Stimulation for Cervical Dystonia (PASTS-CD): study protocol for a multicentre randomised controlled trial

INTRODUCTION

Deep brain stimulation (DBS) has been validated as a safe and effective treatment for refractory cervical dystonia (CD). Globus pallidus internus (GPi) and subthalamic nucleus (STN) are the two main stimulating targets. However, there has been no prospective study to clarify which target is the better DBS candidate for CD. The objective of this trial is to compare directly the efficacy and safety of GPi-DBS and STN-DBS, thereby instructing the selection of DBS target in clinical practice.

METHODS AND ANALYSIS

This multicentre, prospective, randomised, controlled study plans to enrol 98 refractory CD patients. Eligible CD patients will be randomly allocated to GPi-DBS group or STN-DBS group, with the DBS electrodes implanted into the posteroventral portion of GPi or the dorsolateral portion of STN, respectively. The primary outcome will be the improvement of symptomatic severity, measured by the changes in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) severity subscale and the Tsui scale at 3 months, 6 months and 12 months after surgery. The secondary outcomes include the improvement of the TWSTRS-disability subscale, TWSTRS-pain subscale, quality of life, mental and cognitive condition, as well as the differences in stimulation parameters and adverse effects. In addition, this study intends to identify certain predictors of DBS efficacy for CD.

ETHICS AND DISSEMINATION

The trial has been approved by the Medical Ethics Committee of Chinese PLA General Hospital (S2022-613-01). The results of this study will be published in international peer-reviewed journals and shared in professional medical conferences.

TRIAL REGISTRATION NUMBER

NCT05715138.

Bilateral globus pallidus internus (GPi) deep brain stimulation for cervical dystonia: Effects on motor and non-motor symptoms within 5 years follow

BACKGROUND

Cervical Dystonia ("CD") is a movement disorder characterised by sustained muscle contractions in the neck, causing involuntary posturing. Deep brain stimulation ("DBS") of the globus pallidal internus (GPi) is advanced treatment for pharmaco-refractory patients. As CD is a rare disease, cohort studies are often limited to patients of heterogenous disease profile, small sample size or short follow-up. This study firstly aimed to measure the efficacy of GPi-DBS on motor and non-motor symptoms of CD. A secondary aim was to evaluate if clinical factors - such as age, disease duration and baseline disease severity - influence variability of motor outcomes.

METHODS

37 idiopathic CD patients were recruited from movement disorders clinics at The Walton NHS Foundation Trust, Liverpool, UK. Patients were assessed pre-operatively, and 1 year, 3 years and 5 years post-operatively with the following clinical scales: Toronto Western Spasmodic Torticollis Rating Scale ("TWSTRS"), Hospital Anxiety and Depression Scale and EuroQuol-5D.

RESULTS

GPI-DBS significantly improved overall TWSTRS scores by 57% from baseline to 5Y FU (p < 0.001). It also significantly improved TWSTRS severity, disability, and pain sub-scores by 72%, 59% and 46% respectively. We did not find a significant improvement in mood or quality of life scores at 5 years. Similarly, clinical factors at baseline did not correlate with variability in motor outcome.

CONCLUSION

We concluded that GPi-DBS is an effective treatment for motor symptoms and pain in CD. There was limited effect on mood and QoL, and no clinical predictive factors of outcome were identified.

Globus pallidus internus versus subthalamic nucleus deep brain stimulation for isolated dystonia: A 3-year follow-up

BACKGROUND AND PURPOSE

Bilateral deep brain stimulation (DBS) surgery targeting the globus pallidus internus (GPi) or the subthalamic nucleus (STN) is widely used in medication-refractory dystonia. However, evidence regarding target selection considering various symptoms remains limited. This study aimed to compare the effectiveness of these two targets in patients with isolated dystonia.

METHODS

This retrospective study evaluated 71 consecutive patients (GPi-DBS group, n = 32; STN-DBS group, n = 39) with isolated dystonia. Burke-Fahn-Marsden Dystonia Rating Scale scores and quality of life were evaluated preoperatively and at 1, 6, 12, and 36 months postoperatively. Cognition and mental status were assessed preoperatively and at 36 months postoperatively.

RESULTS

Targeting the STN (STN-DBS) yielded effects within 1 month (65% vs. 44%; p = 0.0076) and was superior at 1 year (70% vs. 51%; p = 0.0112) and 3 years (74% vs. 59%; p = 0.0138). For individual symptoms, STN-DBS was preferable for eye involvement (81% vs. 56%; p = 0.0255), whereas targeting the GPi (GPi-DBS) was better for axis symptoms, especially for the trunk (82% vs. 94%; p = 0.015). STN-DBS was also favorable for generalized dystonia at 36-month follow-up (p = 0.04) and required less electrical energy (p < 0.0001). Disability, quality of life, and depression and anxiety measures were also improved. Neither target influenced cognition.

CONCLUSIONS

We demonstrated that the GPi and STN are safe and effective targets for isolated dystonia. The STN has the benefits of fast action and low battery consumption, and is superior for ocular dystonia and generalized dystonia, while the GPi is better for trunk involvement. These findings may offer guidance for future DBS target selection for different types of dystonia.

Does Pallidal Physiology Determine the Success of Unilateral Deep Brain Stimulation in Cervical Dystonia?

Pallidal deep brain stimulation is a well-known surgical treatment for cervical dystonia. The resolution of dystonia typically requires bilateral pallidal stimulation, but in some instances, unilateral stimulation has been successful. In such instances, generally, the stimulated hemisphere was contralateral to the dystonic sternocleidomastoid, but rarely it was ipsilateral. We sought for the physiological features that determine the basis for success and laterality of deep brain stimulation for cervical dystonia with prominent torticollis. We found that pallidal physiology such as high burst to tonic ratio and significant interhemispheric differences in the neuronal firing rate and regularity are critical determinants of successful treatment with unilateral deep brain stimulation. We also found that higher lateralized differences in pallidal physiological parameters predict more robust improvement. In three out of four patients, the stimulation of the hemisphere ipsilateral to the dystonic sternocleidomastoid muscle was effective. These patients did not have any structural brain abnormalities on clinically available imaging studies. One patient responded to the unilateral deep brain stimulation in the hemisphere contralateral to the dystonic sternocleidomastoid. This patient had a structural putamen lesion on brain MRI. These results provide objective parameters determining the success of pallidal deep brain stimulation for treatment of cervical dystonia. The results also depict differences in the pallidal physiology in patients where ipsilateral versus contralateral deep brain stimulation was effective.

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.

Adjuvant medical therapy in cervical dystonia after deep brain stimulation: A retrospective analysis

Background

There is limited information on optimization of symptomatic management of cervical dystonia (CD) after implantation of pallidal deep brain stimulation (DBS).

Objectives

To describe the long-term, “real-world” management of CD patients after DBS implantation and the role of reintroduction of pharmacologic and botulinum toxin (BoNT) therapy.

Methods

A retrospective analysis of patients with focal cervical or segmental craniocervical dystonia implanted with DBS was conducted.

Results

Nine patients were identified with a mean follow-up of 41.7 ± 15.7 months. All patients continued adjuvant oral medication(s) to optimize symptom control post-operatively. Three stopped BoNT and four reduced BoNT dose by an average of 22%. All patients remained on at least one medication used to treat dystonia post-operatively.

Conclusion

Optimal symptom control was achieved with DBS combined with either BoNT and/or medication. We suggest utilization of adjuvant therapies such as BoNT and/or medications if DBS monotherapy does not achieve optimal symptom control.

Bilateral subthalamic nucleus deep brain stimulation for refractory isolated cervical dystonia

Subthalamic nucleus (STN) deep brain stimulation (DBS) has been proven to be an alternative target choice for refractory isolated cervical dystonia (CD). However, assessments of its short and long-term safety, efficacy, and sustained effectiveness have been limited to few reports. Here, we evaluated nine consecutive refractory isolated CD patients who underwent bilateral STN DBS and accepted to short and long-term follow-up in this retrospective study. Seven time points were used to see the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores (pre-operation [baseline], 1, 3, 6, 12, 24 months post-operation and last follow-up) to assess improvement of dystonic symptoms. The 36-item Short-Form General Health Survey (SF-36) scores obtained at pre-operation and last follow-up to assess the changes in quality of life. All patients tolerated surgery well and acquired observable clinical benefits from STN DBS therapy. All patients achieved a considerable improvement in quality of life at the last follow-up. The hardware-related adverse events can be tolerated and the stimulation-related adverse events can be ameliorated by programming. Our data support the idea that bilateral STN DBS is a safety and effective method for the treatment of refractory isolated CD, with persistent and remarkable improvement in both movement and quality of life.

Evolution of Globus Pallidus Targeting for Parkinson's and Dystonia Deep Brain Stimulation: A 15-Year Experience

Objective: The aim of this study is to evaluate the evolution of GPi DBS targeting.

Methods: This retrospective, single-center study included patients implanted with GPi DBS leads for dystonia or PD during the years 2004 to 2018 at the University of Florida Fixel Institute for Neurological Diseases. Each patient underwent a high-resolution targeting study on the day prior to the surgery, which was fused with a high resolution CT scan that was acquired on the day of the procedure. Intraoperative target location was selected using a digitized 3D Schaltenbrand-Bailey atlas. All patients underwent a high-resolution head CT scan without contrast approximately one month after lead implantation and accurate measurement of neuroanatomical lead position was acquired after fusion of pre-operative and post-operative image studies.

Results: We analyzed 253 PD patients with 352 leads and 80 dystonia patients with 141 leads. During 15 years of follow-up, lead locations in the PD group migrated more laterally (β = 0.09, p < 0.0001), posteriorly [slope (β) = 0.04, p < 0.05], and dorsally (β = 0.07, p < 0.001), whereas leads in the dystonia group did not significantly change position aside from a trend in the dorsal direction (β = 0.06, p = 0.053).

Conclusion: The evolving target likely results from multiple factors including improvements in targeting techniques and clinical feedback intraoperatively and post-operatively. Our demonstrates the potential importance of a systematic post-operative DBS lead measurement protocol to ensure quality control and to inform and optimize DBS programming.

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.

Improvement of head and neck range of motion induced by chronic pallidal deep brain stimulation for cervical dystonia

BACKGROUND

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has become an accepted treatment for severe cervical dystonia (CD). Assessment of therapeutic efficacy of DBS mostly focused on head position at rest but hardly on limitations of head and neck mobility, which represent a functionally important impairment in CD.

OBJECTIVE

We aimed to determine prospectively head and neck range of motion (ROM) preoperatively and during chronic bilateral GPi DBS in a series of 11 patients with idiopathic CD or segmental dystonia with prominent CD using a computerized motion analysis.

METHODS

Maximum horizontal rotation of the head in the transverse plane and lateral inclination in the frontal plane were measured preoperatively and at a median of 7 months of chronic GPi DBS, using an ultrasound-based three-dimensional measuring system combined with surface electromyography of cervical muscles.

RESULTS

Horizontal rotation of the head increased from 78.8° ± 31.5° (mean ± SD) preoperatively to 100.7° ± 24.7° with GPi DBS (p < 0.01), thereby improvement of head rotation to the anti-dystonic side (+ 14,2° ± 12,2°) was greater than to the pro-dystonic side (+ 7,8° ± 9,2°; p < 0.05). Movement-related agonistic-antagonistic EMG modulation during head rotation was enhanced with GPi DBS in both sternocleidomastoid (modulation index (MI) 35.8% ± 26.7% preoperatively vs. 67.3% ± 16.9% with GPi DBS, p < 0.01), and splenius capitis muscles (MI 1.9% ± 24.5% preoperatively vs. 44.8% ± 11.6% with GPi DBS, p < 0.01).

CONCLUSION

Chronic bilateral GPi DBS significantly improves head ROM in CD, likely due to enhanced agonist-antagonist EMG activity with reduced co-contraction. Computerized motion analysis provides an objective measurement to assess the improvement of head and neck mobility in CD.

Arching deep brain stimulation in dystonia types

Although medical treatment including botulinum toxic injection is the first-line treatment for dystonia, response is insufficient in many patients. In these patients, deep brain stimulation (DBS) can provide significant clinical improvement. Mounting evidence indicates that DBS is an effective and safe treatment for dystonia, especially for idiopathic and inherited isolated generalized/segmental dystonia, including DYT-TOR1A. Other inherited dystonia and acquired dystonia also respond to DBS to varying degrees. For Meige syndrome (craniofacial dystonia), other focal dystonia, and some rare inherited dystonia, further evidences are still needed to evaluate the role of DBS. Because short disease duration at DBS surgery and absence of fixed musculoskeletal deformity are associated with better outcome, DBS should be considered as early as possible when indicated after careful evaluation including genetic work-up. This review will focus on the factors to be considered in DBS for patients with dystonia and the outcome of DBS in the different types of dystonia.

Deep Brain Stimulation Initiative: Toward Innovative Technology, New Disease Indications, and Approaches to Current and Future Clinical Challenges in Neuromodulation Therapy

Deep brain stimulation (DBS) is one of the most important clinical therapies for neurological disorders. DBS also has great potential to become a great tool for clinical neuroscience research. Recently, the National Engineering Laboratory for Neuromodulation at Tsinghua University held an international Deep Brain Stimulation Initiative workshop to discuss the cutting-edge technological achievements and clinical applications of DBS. We specifically addressed new clinical approaches and challenges in DBS for movement disorders (Parkinson's disease and dystonia), clinical application toward neurorehabilitation for stroke, and the progress and challenges toward DBS for neuropsychiatric disorders. This review highlighted key developments in (1) neuroimaging, with advancements in 3-Tesla magnetic resonance imaging DBS compatibility for exploration of brain network mechanisms; (2) novel DBS recording capabilities for uncovering disease pathophysiology; and (3) overcoming global healthcare burdens with online-based DBS programming technology for connecting patient communities. The successful event marks a milestone for global collaborative opportunities in clinical development of neuromodulation to treat major neurological disorders.

Asleep Deep Brain Stimulation in Patients With Isolated Dystonia: Stereotactic Accuracy, Efficacy, and Safety

OBJECTIVES

Lead placement for deep brain stimulation (DBS) is routinely performed using neuroimaging or microelectrode recording (MER). Recent studies have demonstrated that DBS under general anesthesia using an imaging-guided target technique ("asleep" DBS) can be performed accurately and effectively with lower surgery complication rates than the MER-guided target method under local anesthesia ("awake" DBS). This suggests that asleep DBS may be a more acceptable method. However, there is limited direct evidence focused on isolated dystonia using this method. Therefore, this study aimed to investigate the clinical outcomes and targeting accuracy in patients with dystonia who underwent asleep DBS.

MATERIALS AND METHODS

We examined 56 patients (112 leads) with isolated dystonia who underwent asleep DBS targeting in the globus pallidus internus (GPi) and subthalamic nucleus (STN). The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores were assessed preoperatively and at 12-month follow-up (12 m-FU). The lead accuracy was evaluated by comparing the coordinates of the preoperative plan with those of the final electrode implantation location. Other measures analyzed included stimulation parameters and adverse events (AEs).

RESULTS

For both GPi and STN cohorts, mean BFMDRS motor scores were significantly lower at 12 m-FU (8.9 ± 10.9 and 4.6 ± 5.7 points) than at baseline (22.6 ± 16.4 and 16.1 ± 14.1 points, p < 0.001). The mean difference between the planned target and the distal contact of the leads was 1.33 ± 0.54 mm for the right brain electrodes and 1.50 ± 0.57 mm for the left, determined by Euclidian distance. No perioperative complications or AEs related to the device were observed during the complete follow-up. However, AEs associated with stimulation occurred in 12 and 6 patients in the GPi and STN groups, respectively.

CONCLUSIONS

Asleep DBS may be an accurate, effective, and safe method for treating patients with isolated dystonia regardless of the stimulation target.

Quality of life outcomes after globus pallidus internus deep brain stimulation in idiopathic or inherited isolated dystonia: a meta-analysis

BACKGROUND

Several studies reported the beneficial effects of globus pallidus internus deep brain stimulation (GPi DBS) on health-related quality of life (HRQoL) in patients with inherited or idiopathic isolated dystonia. However, the impact of this intervention on physical and mental/psychological domains and the effects over time remain unclear.

METHODS

We conducted a systematic literature review from January 2000 to May 2019 and performed a meta-analysis of HRQoL outcomes based on the Short Form Health Survey-36 (SF-36) after GPi DBS in patients with inherited or idiopathic isolated dystonia to evaluate the effects of DBS on physical and mental QoL.

RESULTS

Seven studies comprising 144 patients with dystonia (78, generalised; 34, segmental; and 32, focal cervical) were included in this comprehensive analysis. The mean (SD) age at DBS implantation was 41.0 (11.4) years, and the follow-up period after implantation was 3.2 (3.8) years. The random effects model meta-analysis revealed that both physical and mental domains of SF-36 improved following DBS with a significantly larger effect size for the physical domains (effect size=0.781; p<0.0001) compared with the mental domains (effect size=0.533; p<0.0001). A moderator variable analysis demonstrated that effect sizes for HRQoL improvement were maintained over time.

CONCLUSIONS

This is the first meta-analysis that demonstrates significant benefits in HRQoL following DBS in patients with inherited or idiopathic isolated dystonia. The benefits are greater for physical QoL domains compared with mental/psychological QoL. These findings highlight the importance of a comprehensive multidisciplinary approach to improve mental/psychological QoL.

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.

Probabilistic mapping of the antidystonic effect of pallidal neurostimulation: a multicentre imaging study

Deep brain stimulation of the internal globus pallidus is a highly effective and established therapy for primary generalized and cervical dystonia, but therapeutic success is compromised by a non-responder rate of up to 25%, even in carefully-selected groups. Variability in electrode placement and inappropriate stimulation settings may account for a large proportion of this outcome variability. Here, we present probabilistic mapping data on a large cohort of patients collected from several European centres to resolve the optimal stimulation volume within the pallidal region. A total of 105 dystonia patients with pallidal deep brain stimulation were enrolled and 87 datasets (43 with cervical dystonia and 44 with generalized dystonia) were included into the subsequent 'normative brain' analysis. The average improvement of dystonia motor score was 50.5 ± 30.9% in cervical and 58.2 ± 48.8% in generalized dystonia, while 19.5% of patients did not respond to treatment (<25% benefit). We defined probabilistic maps of anti-dystonic effects by aggregating individual electrode locations and volumes of tissue activated (VTA) in normative atlas space and ranking voxel-wise for outcome distribution. We found a significant relation between motor outcome and the stimulation volume, but not the electrode location per se. The highest probability of stimulation induced motor benefit was found in a small volume covering the ventroposterior globus pallidus internus and adjacent subpallidal white matter. We then used the aggregated VTA-based outcome maps to rate patient individual VTAs and trained a linear regression model to predict individual outcomes. The prediction model showed robustness between the predicted and observed clinical improvement, with an r2 of 0.294 (P < 0.0001). The predictions deviated on average by 16.9 ± 11.6 % from observed dystonia improvements. For example, if a patient improved by 65%, the model would predict an improvement between 49% and 81%. Results were validated in an independent cohort of 10 dystonia patients, where prediction and observed benefit had a correlation of r2 = 0.52 (P = 0.02) and a mean prediction error of 10.3% (±8.9). These results emphasize the potential of probabilistic outcome brain mapping in refining the optimal therapeutic volume for pallidal neurostimulation and advancing computer-assisted planning and programming of deep brain stimulation.

Predictive factors for outcome of pallidal deep brain stimulation in cervical dystonia

OBJECTIVE

Primary cervical dystonia (CD) is characterized by abnormal contractions of neck muscles. Globus pallidus internus deep brain stimulation (GPi-DBS) is recognized as an effective therapy for patients with refractory CD, but the prognostic factors need further research. Our study investigated the predictive factors of clinical outcomes in CD patients who underwent GPi-DBS.

PATIENTS AND METHODS

Patients (n = 23) who underwent GPi-DBS at Chinese PLA General Hospital from March 2012 to April 2018 were included in our analysis. Their scores of Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and Tsui were acquired at baseline and at the last follow-up visit. Percent improvement in these scores were compared between the categorical variables. Correlations between outcomes and continuous demographic and clinical variables were calculated.

RESULTS

Patients showed significant improvement in TWSTRS total (55.71 %), severity (48.75 %), disability (57.05 %), pain (63.67 %) scores and total Tsui score (46.07 %, all P ﹤0.001). Follow-up duration was positively correlated with percent improvement in TWSTRS total (rho = 0.594, P =  0.003), severity (rho = 0.581, P =  0.004) and disability (rho = 0.470, P =  0.023) scores. No significant differences in the outcomes were found between any pair of the categorical variables.

CONCLUSIONS

Follow-up duration was the only independent factor correlated to the outcomes of GPi-DBS for CD patients. However, follow-up duration is an indefinite factor prior to surgery, thus further studies are needed before the final conclusions of prognostic factors are established.

Range of voluntary neck motility predicts outcome of pallidal DBS for cervical dystonia

BACKGROUND

The effectiveness of pallidal deep brain stimulation (GPi DBS) for cervical dystonia has been extensively described, but controversies exist about which prognostic factor is clinically useful. We previously reported that classification of tonic- or phasic-type cervical dystonia is useful for predicting clinical prognosis; however, the approach used by physicians to distinguish between the two types remains subjective.

OBJECTIVE

The aim of this study was to develop a prognostic factor of GPi DBS for cervical dystonia.

METHODS

By identifying distributions of range of motion scores between phasic- and tonic-type cervical dystonia, a new prognostic factor group was developed based on whether the patients could voluntarily move their head to the opposite side against dystonic motions. The prognosis for GPi DBS in the two groups was analyzed according to the time sequence.

RESULTS

Patients who were able to move their head past the midline had a better long-term prognosis after GPi DBS than did those who could not. In the early post-operative phase, there were no significant differences in the clinical outcomes between the two groups.

CONCLUSION

A range of voluntary neck motility with respect to the midline is an objective factor that is useful in predicting the prognosis of patients with cervical dystonia. This result renders needs for future study addressing neuroplastic changes in the brain network caused by GPi DBS.

Quality of life outcomes after deep brain stimulation in dystonia: A systematic review

Dystonia is an incurable movement disorder which can cause not only physical but also mental problems, leading to impaired health-related quality of life (HRQoL). For patients with dystonia refractory to medical treatment, deep brain stimulation (DBS) is a well-established surgical treatment. The objective of this systematic review is to provide a better understanding of HRQoL outcomes after DBS for dystonia. A search of the literature was conducted using Medline (PubMed), Embase, and Cochrane Library databases in May 2019. HRQoL outcomes after DBS along with motor outcomes were reported in a total of 36 articles involving 610 patients: 21 articles on inherited or idiopathic isolated dystonia, 5 on tardive dystonia, 3 on cerebral palsy, 2 on myoclonus-dystonia, 1 on X-linked dystonia-parkinsonism, and 3 on mixed cohorts of different dystonia subtypes. DBS improved motor symptoms in various subtypes of dystonia. Most studies on patients with inherited or idiopathic isolated dystonia showed significant improvement in physical QoL, whereas gains in mental QoL were less robust and likely related to the complexity of associated neuropsychiatric problems. HRQoL outcomes beyond 5 years remain scarce. Although the studies on patients with other subtypes of dystonia also demonstrated improvement in HRQoL after DBS, the interpretation is difficult because of a limited number of articles with small cohorts. Most articles employed generic measures (e.g. Short Form Health Survey-36) and this highlights the critical need to develop and to utilize sensitive and disease-specific HRQoL measures. Finally, long-term HRQoL outcomes and predictors of HRQoL should also be clarified.

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.

Importance of the initial response to GPi deep brain stimulation in dystonia: A nine year quality of life study

BACKGROUND

Long-term efficacy of deep brain stimulation (DBS) on health-related quality-of-life (HRQoL) for isolated dystonia is not well established. This study aims to determine the long-term impact of DBS on HRQoL outcomes and identify clinical predictors.

METHODS

We retrospectively investigated 16 inherited or idiopathic isolated dystonia patients treated with bilateral globus pallidus internus DBS who were followed beyond 9 years at our center. The cohort consisted of 9 males, 7 females; 10 generalized, 6 segmental; mean (range) age at implantation, 37.0 (8-67) years; mean follow-up duration after implantation, 10.9 (9-13) years. We employed the Unified Dystonia Rating Scale for motor and Short Form Health Survey for HRQoL assessments to monitor the change longitudinally. We analyzed the changes in motor and HRQoL at 1-2 years (short-term) and ≥9 years (long-term) follow-up as compared to baseline with a Wilcoxon signed-rank test. We assessed the factors that predicted motor and HRQoL improvement with univariate regression analyses.

RESULTS

Motor (41.6%; p = 0.004) and HRQoL (total score, p = 0.039) improvements remained significant at long-term follow-up and, in the regression analysis, change in HRQoL outcomes correlated significantly with change in motor outcomes (R² = 0.384, p = 0.010). Additionally, short-term motor and HRQoL improvements predicted the long-term motor (R² = 0.384, p = 0.010) and HRQoL (total score, R² = 0.594, p < 0.001) outcomes, respectively.

CONCLUSION

Motor and HRQoL improvements with DBS in isolated dystonia remain sustained for nearly a decade and may largely be predictable by the short-term response to DBS.

Deep Brain Stimulation Versus Peripheral Denervation for Cervical Dystonia: A Systematic Review and Meta-Analysis

BACKGROUND

Cervical dystonia is a disabling medical condition that drastically decreases quality of life. Surgical treatment consists of peripheral nerve denervation procedures with or without myectomies or deep brain stimulation (DBS). The current objective was to compare the efficacy of peripheral denervation versus DBS in improving the severity of cervical dystonia through a systematic review and meta-analysis.

METHODS

A search of PubMed, MEDLINE, EMBASE, and Web of Science electronic databases was conducted in accordance with PRISMA guidelines. Preoperative and postoperative Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total scores were used to generate standardized mean differences and 95% confidence intervals (CIs), which were combined in a random-effects model. Both mean percentage and absolute reduction in TWSTRS scores were calculated. Absolute reduction was used for forest plots.

RESULTS

Eighteen studies met the inclusion criteria, comprising 870 patients with 180 (21%) undergoing DBS and 690 (79%) undergoing peripheral denervation procedures. The mean follow-up time was 31.5 months (range, 12-38 months). In assessing the efficacy of each intervention, forest plots revealed significant absolute reduction in total postoperative TWSTRS scores for both peripheral denervation (standardized mean difference 1.54; 95% CI 1.42-1.66) and DBS (standardized mean difference 2.07; 95% CI 1.43-2.71). On subgroup analysis, DBS therapy was significantly associated with improvement in postoperative TWSTRS severity (standardized mean difference 2.08; 95% CI 1.66-2.50) and disability (standardized mean difference 2.12; 95% CI 1.57-2.68) but not pain (standardized mean difference 1.18; 95% CI 0.80-1.55).

CONCLUSIONS

Both peripheral denervation and DBS are associated with a significant reduction in absolute TWSTRS total score, with no significant difference in the magnitude of reduction observed between the 2 treatments. Further comparative data are needed to better evaluate the long-term results of both interventions.

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.

Deep Brain Stimulation for the Dystonias: Evidence, Knowledge Gaps, and Practical Considerations

BACKGROUND

Deep brain stimulation (DBS) of the globus pallidus internus (GPi-DBS) is among the most effective treatment options for dystonias. Because the term "dystonia" is defined by a characteristic phenomenology of involuntary muscle contractions, which may present with a large clinical and pathogenetic heterogeneity, decision making for or against GPi-DBS can be difficult in individual patients.

METHODS

A search of the PubMed database for research and review articles, focused on "deep brain stimulation" and "dystonia" was used to identify clinical trials and to determine current concepts in the surgical management of dystonia. Patient selection in previous studies was recategorized by the authors using the new dystonia classification put forward by a consensus committee of experts in dystonia research. The evidence and knowledge gaps are summarized and commented by the authors taking into account expert opinion and personal clinical experience for providing practical guidance in patient selection for DBS in dystonia.

RESULTS

The literature review shows that pallidal deep brain stimulation is most effective in patients with isolated dystonia irrespective of the underlying etiology. In contrast, patients with combined dystonias are less likely to benefit from DBS, because the associated neurological symptoms (e.g., hypotonia or ataxia), with the exception of myoclonus, do not respond to pallidal neurostimulation.

CONCLUSIONS

It is important to recognize the clinical features of dystonia, because the distinction between isolated and combined dystonia syndromes may predict the treatment response to pallidal deep brain stimulation. The aim of this review is to help guide clinicians with advising patients about deep brain stimulation therapy for dystonia and refering appropriate candidates to surgical centers.

Causes of failure of pallidal deep brain stimulation in cases with pre-operative diagnosis of isolated dystonia

INTRODUCTION

Pallidal deep brain stimulation (GPi-DBS) is an effective therapy for isolated dystonia, but 10-20% of patients show improvement below 25-30%. We here investigated causes of insufficient response to GPi-DBS in isolated dystonia in a cross-sectional study.

METHODS

Patients with isolated dystonia at time of surgery, and <30% improvement on the Burke-Fahn-Marsden dystonia-rating-scale (BFMDRS) after ≥6 months of continuous GPi-DBS were videotaped ON and OFF stimulation, and history, preoperative videos, brain MRI, medical records, stimulation settings, stimulation system integrity, lead location, and genetic information were obtained and reviewed by an expert panel.

RESULTS

22 patients from 11 centres were included (8 men, 14 women; 9 generalized, 9 segmental, 3 focal, 1 bibrachial dystonia; mean (range): age 48.7 (25-72) years, disease duration 22.0 (2-40) years, DBS duration 45.5 (6-131) months). Mean BFMDRS-score was 31.7 (4-93) preoperatively and 32.3 (5-101) postoperatively. Half of the patients (n = 11) had poor lead positioning alone or in combination with other problems (combined with: other disease n = 6, functional dystonia n = 1, other problems n = 2). Other problems were disease other than isolated inherited or idiopathic dystonia (n = 5), fixed deformities (n = 2), functional dystonia (n = 3), and other causes (n = 1). Excluding patients with poor lead location from further analysis, non-isolated dystonia accounted for 45.5%, functional dystonia for 27.3%, and fixed deformities for 18.2%. In patients with true isolated dystonia, lead location was the most frequent problem.

CONCLUSION

After exclusion of lead placement and stimulation programming issues, non-isolated dystonia, functional dystonia and fixed deformities account for the majority of GPi-DBS failures in dystonia.

Rescue Procedures after Suboptimal Deep Brain Stimulation Outcomes in Common Movement Disorders

Deep brain stimulation (DBS) is a unique, functional neurosurgical therapy indicated for medication refractory movement disorders as well as some psychiatric diseases. Multicontact electrodes are placed in "deep" structures within the brain with targets varying depending on the surgical indication. An implanted programmable pulse generator supplies the electrodes with a chronic, high frequency electrical current that clinically mimics the effects of ablative lesioning techniques. DBS's efficacy has been well established for its movement disorder indications (Parkinson's disease, essential tremor, and dystonia). However, clinical outcomes are sometimes suboptimal, even in the absence of common, potentially reversible complications such as hardware complications, infection, poor electrode placement, and poor programming parameters. This review highlights some of the rescue procedures that have been explored in suboptimal DBS cases for Parkinson's disease, essential tremor, and dystonia. To date, the data is limited and difficult to generalize, but a large majority of published reports demonstrate positive results. The decision to proceed with such treatments should be made on a case by case basis. Larger studies are needed to clearly establish the benefit of rescue procedures and to establish for which patient populations they may be most appropriate.

Deep Brain Stimulation in Rare Inherited Dystonias

BACKGROUND

Rare causes of inherited movement disorders often present with a debilitating phenotype of dystonia, sometimes combined with parkinsonism and other neurological signs. Since these disorders are often resistant to medications, DBS may be considered as a possible treatment.

METHODS

Patients with identified genetic diseases (ataxia-telangiectasia, chorea-achantocytosis, dopa-responsive dystonia, congenital nemaline myopathy, methylmalonic aciduria, neuronal ceroid lipofuscinosis, spinocerebellar ataxia types 2 and 3, Wilson's disease, Woodhouse-Sakati syndrome, methylmalonic aciduria, and X trisomy) and disabling dystonia underwent bilateral GPi DBS (bilateral thalamic Vim nucleus in 1 case). The primary outcome was the difference in the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) between baseline, 1 year and last available follow-up. Preoperative factors such as age at surgery, disease duration at surgery, proportion of life lived with dystonia and severity of dystonia were correlated to the primary outcome.

RESULTS

Eleven patients were operated between February 2003 and December 2013. Age and duration of disease at time of surgery were 30 ± 19 and 12.5 ± 15.7 years, respectively. DBS effects on dystonia severity were variable but overall marginally effective, with a mean improvement of 7.9% (p = 0.39) at 1-year follow-up and 16.7% (p = 0.46) at last follow-up (mean 47.3 ± 19.9 months after surgery). No preoperative factors were identified to predict the surgical outcome.

CONCLUSION

Our findings support the current knowledge that DBS is modestly effective in treating rare inherited dystonias with a combined phenotype. However, the BFMDRS might not be the best tool to measure outcome in these severely affected patients.

Surgery for Dystonia and Tremor

Surgical procedures for dystonia and tremor have evolved over the past few decades, and our understanding of risk, benefit, and predictive factors has increased substantially in that time. Deep brain stimulation (DBS) is the most utilized surgical treatment for dystonia and tremor, though lesioning remains an effective option in appropriate patients. Dystonic syndromes that have shown a substantial reduction in severity secondary to DBS are isolated dystonia, including generalized, cervical, and segmental, as well as acquired dystonia such as tardive dystonia. Essential tremor is quite amenable to DBS, though the response of other forms of postural and kinetic tremor is not nearly as robust or consistent based on available evidence. Regarding targeting, DBS lead placement in the globus pallidus internus has shown marked efficacy in dystonia reduction. The subthalamic nucleus is an emerging target, and increasing evidence suggests that this may be a viable target in dystonia as well. The ventralis intermedius nucleus of the thalamus is the preferred target for essential tremor, though targeting the subthalamic zone/caudal zona incerta has shown promise and may emerge as another option in essential tremor and possibly other tremor disorders. In the carefully selected patient, DBS and lesioning procedures are relatively safe and effective for the management of dystonia and tremor.

Update on Deep Brain Stimulation for Dyskinesia and Dystonia: A Literature Review

Deep brain stimulation (DBS) has been an established surgical treatment option for dyskinesia from Parkinson disease and for dystonia. The present article deals with the timing of surgical intervention, selecting an appropriate target, and minimizing adverse effects. We provide an overview of current evidences and issues for dyskinesia and dystonia as well as emerging DBS technology.

Eligibility Criteria for Deep Brain Stimulation in Parkinson’s Disease, Tremor, and Dystonia

In this review, the available evidence to guide clinicians regarding eligibility for deep brain stimulation (DBS) in the main conditions in which these forms of therapy are generally indicated—Parkinson’s disease (PD), tremor, and dystonia—is presented. In general, the literature shows that DBS is effective for PD, essential tremor, and idiopathic dystonia. In these cases, key points in patient selection must include the level of disability and inability to manage symptoms using the best available medical therapy. Results are, however, still not optimal when dealing with other aetiologies, such as secondary tremors and symptomatic dystonia. Also, in PD, issues such as age and neuropsychiatric profile are still debatable parameters. Overall, currently available literature is able to guide physicians on basic aspects of patient selection and indications for DBS; however, a few points are still debatable and controversial. These issues should be refined and clarified in future studies.

Different clinical course of pallidal deep brain stimulation for phasic- and tonic-type cervical dystonia

BACKGROUND

Dystonia has been treated well using deep brain stimulation at the globus pallidus internus (GPi DBS). Dystonia can be categorized as two basic types of movement, phasic-type and tonic-type. Cervical dystonia is the most common type of focal dystonia, and sequential differences in clinical outcomes between phasic-type and tonic-type cervical dystonia have not been reported.

METHODS

This study included a retrospective cohort of 30 patients with primary cervical dystonia who underwent GPi DBS. Age, disease duration, dystonia direction, movement types, employment status, relevant life events, and neuropsychological examinations were analyzed with respect to clinical outcomes following GPi DBS.

RESULTS

The only significant factor affecting clinical outcomes was movement type (phasic or tonic). Sequential changes in clinical outcomes showed significant differences between phasic- and tonic-type cervical dystonia. A delayed benefit was found in both phasic- and tonic-type dystonia.

CONCLUSIONS

The clinical outcome of phasic-type cervical dystonia is more favorable than that of tonic-type cervical dystonia following GPi DBS.

DBS in Dystonia and Other Hyperkinetic Movement Disorders

OPINION STATEMENT

The diagnosis and appropriate treatment of hyperkinetic movement disorders require a work up of potentially reversible metabolic, infectious and structural disorders as well as side effects of current medication. In pharmacoresistant movement disorders with a disabling impact on quality of life, deep brain stimulation (DBS) should be considered. At different targets, DBS has become an established therapy for Parkinson's disease (GPi-STN), tremor (VIM) and primary dystonia (GPi) with reasonable perioperative risks and side effects, established guidelines and some clinical and radiological predictive factors. In contrast, for other hyperkinetic movement disorders, including secondary dystonia, Gilles de la Tourette, chorea and ballism, only few data are available. Definite targets are not well defined, and reported results are of less magnitude than those of the recognized indications. In this expanding therapeutical field without worked out recommendations, an individual approach is needed with DBS indication assessment only after rigorous multidisciplinary scrutiny, restricted to expert centres.

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.

Quantitative assessment of brain iron by R2* relaxometry in patients with cervical dystonia

BACKGROUND

The pathophysiology of cervical dystonia is poorly understood. Increased brain iron deposition has been described in different movement disorders. Our aim was to investigate brain iron content in patients with cervical dystonia, using R2* relaxation rate, a validated MRI marker of brain iron level.

METHODS

Twelve female patients with primary focal cervical dystonia (mean age: 45.4 ± 8.0 years) and 12 age-matched healthy female subjects (mean age: 45.0 ± 8.0 years) underwent 3T MRI to obtain regional R2* relaxation rates of the thalamus, caudate nucleus, putamen, and globus pallidus (GP). Regions of interest were delineated automatically on T1-weighted MRIs.

RESULTS

R2* values in the putamen were positively correlated with age. Patients with cervical dystonia showed elevated R2* values in the GP.

CONCLUSIONS

This pilot study provides the first quantitative support for increased brain iron deposition in cervical dystonia. Further studies are needed to explore the implications of this finding.

Long-term neuropsychiatric outcomes after pallidal stimulation in primary and secondary dystonia

OBJECTIVE

To evaluate changes in the diagnosis of Axis I psychiatric disorders in patients with primary and secondary dystonia after deep brain stimulation (DBS) of the globus pallidus internus (GPi).

METHODS

Structured Clinical Interviews for the DSM-IV, Axis I psychiatric disorders, were prospectively performed before and after surgery. Diagnoses were made based on DSM-IV criteria. Psychiatric disorders were grouped into 5 categories: mood, anxiety, addiction, obsessive-compulsive disorders, and psychosis. Patients could be stratified to more than one category. Rates for unchanged diagnoses, diagnoses in remission, and new-onset diagnoses after surgery for each category were calculated.

RESULTS

Fifty-seven patients with primary and secondary dystonia were included. Mean ± SD age at surgery and dystonia duration at time of surgery was 50.6 ± 13.8 and 19.0 ± 13.2 years, respectively. Preoperatively, 37 Axis I diagnoses were made in 25 patients, 43.8% of those presenting with at least 1 Axis I diagnosis (mostly mood and anxiety disorders). Mean ± SD duration of psychiatric follow-up was 24.4 ± 19.6 months. Overall, after surgery no significant changes (p = 0.16) were found in Axis I diagnoses (23 patients, 40.3%): 27 (73%) unchanged, 10 (27%) in complete remission, and 4 (12.9%) new-onset diagnoses.

CONCLUSIONS

Our results support the overall psychiatric stability of patients with primary and secondary dystonia treated with GPi DBS. However, considering the high psychiatric morbidity in the dystonia population, psychiatric assessments before and after surgery are strongly recommended.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that GPi DBS does not change Axis I psychiatric diagnoses in patients with primary and secondary dystonia.