What happened to posteroventral pallidotomy for Parkinson's disease and dystonia?

Outcomes of Unilateral Pallidotomy in Focal and Hemidystonia Cases: A Single-Blind Cohort Study

BACKGROUND

The role of deep brain stimulation in the treatment of dystonia has been widely documented. However, there is limited literature on the outcome of lesioning surgery in unilateral dystonia.

OBJECTIVE

We restrospectively reviewed our cases of focal and hemidystonia undergoing unilateral Pallidotomy at our institute to evaluate the short-term and long-term outcome.

METHODS

Patients who underwent radiofrequency lesioning of GPi for unilateral dystonia between 1999 and 2019 were retrospectively reviewed. All patients were evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Dystonia Disability Scale (DDS) preoperatively at the short term follow-up (<1 year) and at long-term follow-up (2-7.5 years). Video recordings performed at these time points were independently reviewed by a blinded movement disorders specialist.

RESULTS

Eleven patients were included for analysis. The preoperative, short-term, and long-term follow-up motor BFMDRS and DDS scores were 15.5 (IQR [interquartile range]: 10.5, 23.75) and 10.5 (IQR: 6.0, 14.5); 3.0 (IQR: 1.0, 6.0, P = 0.02) and 3.0 (IQR: 3.0, 8.0, P = 0.016); and 14.25 (IQR: 4.0, 20.0, P = 0.20) and 10.5 (IQR: 2.0, 15.0, P = 0.71) respectively. For observers B, the BFMDRS scores at the same time points were 19 (IQR: 12.5, 27.0), 7.5 (IQR: 6.0, 15.0, P = 0.002), and 21 (IQR: 7.0, 22.0, P = 0.65) respectively. The improvement was statistically significant for all observations at short-term follow-up but not at long-term follow-up.

CONCLUSION

Pallidotomy is effective for hemidystonia or focal dystonia in the short term. Continued benefit was seen in the longer term in some patients, whereas others worsened. Larger studies may be able to explain this in future.

Neurosurgical management of non-spastic movement disorders

BACKGROUND

Non-spastic movement disorders in children are common, although true epidemiologic data is difficult to ascertain. Children are more likely than adults to have hyperkinetic movement disorders defined as tics, dystonia, chorea/athetosis, or tremor. These conditions manifest from acquired or heredodegenerative etiologies and often severely limit function despite medical and surgical management paradigms. Neurosurgical management for these conditions is highlighted.

METHODS

We performed a focused review of the literature by searching PubMed on 16 May 2023 using key terms related to our review. No temporal filter was applied, but only English articles were considered. We searched for the terms (("Pallidotomy"[Mesh]) OR "Rhizotomy"[Mesh]) OR "Deep Brain Stimulation"[Mesh], dystonia, children, adolescent, pediatric, globus pallidus, in combination. All articles were reviewed for inclusion in the final reference list.

RESULTS

Our search terms returned 37 articles from 2004 to 2023. Articles covering deep brain stimulation were the most common (n = 34) followed by pallidotomy (n = 3); there were no articles on rhizotomy.

DISCUSSION

Non-spastic movement disorders are common in children and difficult to treat. Most of these patients are referred to neurosurgery for the management of dystonia, with modern neurosurgical management including pallidotomy, rhizotomy, and deep brain stimulation. Historically, pallidotomy has been effective and may still be preferred in subpopulations presenting either in status dystonicus or with high risk for hardware complications. Superiority of DBS over pallidotomy for secondary dystonia has not been determined. Rhizotomy is an underutilized surgical tool and more study characterizing efficacy and risk profile is indicated.

Research status and hotspots in the surgical treatment of tremor in Parkinson's disease from 2002 to 2022: a bibliometric and visualization analysis

Objective

This study aims to investigate the research status and hotspots of surgical treatment for tremor in Parkinson's disease (PD) from 2002 to 2022, utilizing bibliometric and visual analysis. Additionally, it aims to offer insights into future research trends in this field.

Methods

This study collected publications on the surgical treatment of tremor in PD from 2002 to 2022 using the Web of Science (WOS) database. CiteSpace, VOSviewer, and Scimago Graphica were employed to quantify the number of publications and analyze the bibliographic information networks, including the contributions of countries/cities, authors, keywords, and co-cited references.

Results

A total of 2,815 publications were included in the study, revealing that 541 scientific institutions experienced an increase in publications from 2002 to 2022. Michael Okun emerged as the most productive author, and the United States emerged as the leading hub for research. The study identified 772 keywords. Noteworthy citation bursts and long-term activity were observed in pallidotomy, bilateral stimulation, and focused ultrasound thalamotomy. The top 10 highly co-cited references comprised eight deep brain stimulation (DBS) studies (including two follow-up studies and six randomized controlled trials), one randomized controlled trial on focused ultrasound, and one consensus on tremor.

Conclusion

This study uses an in-depth and systematic bibliometric and visualization analysis to visualize the evolution of research and identify emerging hotspots. The identified hotspots are as follows: Firstly, DBS has received significant attention and widespread recognition as a surgical treatment for tremor in PD. Secondly, there are various key aspects to consider in DBS, such as operative indications, operative targets, and surgical protocols. Lastly, magnetic resonance-guided focused ultrasound (MRgFUS) has emerged as a promising treatment option in the surgical management of tremor in Parkinson's disease. This research also provides insights into the phenomenon of these hotspots, offering valuable prompts and reminders for further research.

Pros and Cons of Ablation for Functional Neurosurgery in the Neurostimulation Age

Should one recommend stereotactic ablation for Parkinson disease, tremor, dystonia, and obsessive compulsive disorder, in this era of DBS? The answer depends on several variables such as the symptoms to treat, the patient's preferences and expectations, the surgeons' competence and preference, the availability of financial means (by government health care, by private insurance), the geographical issues, and not least the current and dominating fashion at that particular time. Both ablation and stimulation can be either used alone or even combined (provided expertise in both of them) to treat various symptoms of movement and mind disorders.

Evaluation of Deep Brain Stimulation (DBS) Lead Biomechanical Interaction with Brain Tissue

The current study aims to examine the effect of material properties on implanted leads used for deep brain stimulation (DBS) using finite element (FE) analysis to investigate brain deformation around an implanted DBS lead in response to daily head accelerations. FE analysis was used to characterize the relative motion of the DBS lead in a suite of fifteen cases sampled from a previously derived kinematic envelope representative of everyday activities describing translational and rotational pulse shape, magnitude, and duration. Load curves were applied to the atlas-based brain model (ABM) with a scaled Haversine acceleration pulse in four directions of rotation: + X, - Y, + Y, and + Z. In addition to the fifteen sampled cases, six experimental cases taken from a previous literature review were also simulated for comparison. The current investigation found that there was very little difference in brain response for the DBS leads with two different material properties. In general, the brain and DBS lead experienced the greatest deformation during rotation about the Z axis for similar load cases. In conclusion, this study showed that there was no significant difference in implanted DBS lead deformation based on lead material properties.

Seven-year resolution of cervical dystonia after unilateral pallidotomy: A case report

Background

Reports on the long-term effects of pallidotomy for cervical dystonia remain scarce.

Case Description

We report a case of cervical dystonia successfully treated by unilateral pallidotomy. The patient was a 29-year-old man without past medical and family history of cervical dystonia. At the age of 28 years, neck rotation to the right with right shoulder elevation developed and gradually became worse. After symptoms failed to respond to repetitive botulinum toxin injections and oral medications, he underwent left pallidotomy, which resulted in significant improvement of cervical dystonia and shoulder elevation without surgical complications. At the 3-month evaluation, the symptoms completely improved. The Toronto Western Spasmodic Torticollis Rating Scale score dramatically improved from 39 points before surgery to 0 points at 7-year postoperative evaluation.

Conclusion

This case suggests that unilateral pallidotomy can be an alternative treatment option for cervical dystonia.

Neuromodulation for temporal lobe epilepsy: a scoping review

Temporal lobe epilepsy (TLE) is difficult to treat as it is often refractory to treatment. Apart from traditional medical treatment, surgical resection is also a choice of treatment, but it may be associated with significant cognitive deficits. ‌As a result, treatment strategies using targeted and adjustable stimulation of malfunctioning brain circuits have been developed. These neuromodulatory therapies using approaches of electric and magnetic neuromodulation are already in clinical use for refractory epilepsy while others such as optogenetics, chemo-genetics and ultrasound modulation are being tested in pre-clinical TLE animal models. In this review, we conducted an in-depth literature search on the clinically available neuromodulatory approaches for TLE, focusing on the possible mechanism of action and the clinical outcomes including adverse effects. Techniques that are currently explored in preclinical animal models but may have therapeutic applications in future are also discussed. The efficacy and subsequent adverse effects vary among the different neuromodulatory approaches and some still have unclear mechanisms of action in TLE treatment. Further studies evaluating the benefits and potential limitations are needed. Continued research on the therapeutic mechanisms and the epileptic brain network is critical for improving therapies for TLE.

Bilateral pallidotomy for acquired or heredodegenerative generalized dystonia in children

OBJECTIVE

Dystonias are relatively rare disorders characterized by sustained or intermittent muscle contractions causing abnormal movements or postures. Generalized dystonia is a therapeutic challenge because medications are unable to control dystonia adequately in most patients. These patients may be candidates for surgical therapy. The commonly used surgical procedures in these patients are pallidotomy and deep brain stimulation. Limited studies are available on the role of pallidotomy in children with acquired/heredodegenerative generalized dystonia. The objective of this study was to describe the authors’ experience with bilateral pallidotomy in this group of patients.

METHODS

The authors retrospectively reviewed all pediatric patients (less than 18 years of age) with acquired/heredodegenerative generalized dystonia who underwent bilateral simultaneous pallidotomy at their center between January 2014 and January 2021. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores before and after surgery were recorded. Complications arising after the procedure were recorded as well.

RESULTS

Ten patients (8 male and 2 female) with a mean (range) age of 11.1 (5–17) years were included in this study. The mean duration between disease onset and surgical intervention was 3.9 years. Two patients presented in status dystonicus. The mean ± SD (range) preoperative BFMDRS score of the patients without status dystonicus (n = 8) was 80 ± 18.9 (59.5–108). The mean ± SD BFMDRS score at the time of discharge from the hospital after surgery was 58.8 ± 37.9. Three patients had more than 20% change in BFMDRS score at the time of discharge from the hospital. The mean improvement was 25.5% at the end of 1 year. Of 5 surviving patients in the non–status dystonicus group, 3 patients had more than 40% change in BFMDRS score while the other 2 patients developed recurrence at the last follow-up (4.5 years). Status dystonicus abated after bilateral pallidotomy in both patients. Permanent bulbar complications were seen in 2 patients.

CONCLUSIONS

Bilateral pallidotomy may result in clinically significant improvement in children with acquired/heredodegenerative generalized dystonia, although the benefits should be closely weighed against the risk of irreversible bulbar dysfunction. It is a viable option for children in resource-limited settings.

An update on advanced therapies for Parkinson's disease: From gene therapy to neuromodulation

Advanced Parkinson's disease (PD) is characterized by increasingly debilitating impaired movements that include motor fluctuations and dyskinesias. At this stage of the disease, pharmacological management can result in unsatisfactory clinical benefits and increase the occurrence of adverse effects, leading to the consideration of advanced therapies. The scope of this review is to provide an overview of currently available therapies for advanced PD, specifically levodopa–carbidopa intestinal gel, continuous subcutaneous apomorphine infusion, radiofrequency ablation, stereotactic radiosurgery, MRI-guided focused ultrasound, and deep brain stimulation. Therapies in clinical trials are also discussed, including novel formulations of subcutaneous carbidopa/levodopa, gene-implantation therapies, and cell-based therapies. This review focuses on the clinical outcomes and adverse effects of the various therapies and also considers patient-specific characteristics that may influence treatment choice. This review can equip providers with updated information on advanced therapies in PD to better counsel patients on the available options.

Surgical Outcomes in Rare Movement Disorders: A Report of Seventeen Patients from India and Review of Literature

Background:

Rare movement disorders (RMDs) throw remarkable challenges to their appropriate management particularly when they are medically refractory. We studied the outcome of functional neurosurgery among patients with RMDs.

Methods:

Retrospective chart-review from 2006 to 2021 of patients with RMDs who underwent either Deep brain Stimulation (DBS) or lesional surgeries in the department of Neurology and Neurosurgery at a tertiary care centre.

Results:

Seventeen patients were included. Generalized dystonia (11 patients, 64.7%) and tremor (5 patients, 29.4%) were the most common indication for surgery whereas, Wilson’s disease (8 patients, 47.1%) and Neurodegeneration with brain iron accumulation (5 patients, 29.4%) were the most common aetiology. Sixteen patients (94.1%) had objective clinical improvement. Significant improvement was noted in the dystonia motor scores both at 6-months and 12-months follow-up (n = 11, p-value of <0.01 and 0.01 respectively). Comparison between DBS and lesional surgery showed no significant difference in the outcomes (p = 0.95 at 6-months and p = 0.53 at 12-months), with slight worsening of scores in the DBS arm at 12-months. Among five patients of refractory tremor with Wilson’s disease, there was remarkable improvement in the tremor scores by 85.0 ± 7.8% at the last follow-up. Speech impairment was the main complication observed with most of the other adverse events either transient or reversible.

Discussion:

Surgical options should be contemplated among patients with disabling medically refractory RMDs irrespective of the aetiology. Key to success lies in appropriate patient selection. In situations when DBS is not feasible, lesional surgeries can offer an excellent alternative with comparable efficacy and safety.

Combined Unilateral Radiofrequency Lesioning of the Motor Thalamus, Field of Forel, and Zona Incerta: A Series of Cases With Dystonia

BACKGROUND

Dystonia is a group of disorders characterized by involuntary slow repetitive twisting movements and/or abnormal posture. Surgical options such as neuromodulation through deep brain stimulation and neuroablative procedures are available for patients who do not respond to conservative treatment.

OBJECTIVE

To present our series of patients with dystonia who were treated with stereotactic combined unilateral radiofrequency lesioning of the motor thalamus, field of Forel, and zona incerta.

METHODS

Medical records of 50 patients with dystonia who were treated with unilateral combined lesions were reviewed. Outcomes of the surgical procedure were evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (with movement and disability subscales) and Unified Parkinson's Disease Rating Scale-tremor items.

RESULTS

Based on the symptoms, patients were categorized as having generalized dystonia (34%), hemidystonia (30%), and dystonic tremor (DT) (36%). Primary/idiopathic dystonia, primary genetic/hereditary dystonia, and secondary dystonia accounted for 16%, 4%, and 80% of patients, respectively. The mean follow-up duration was 156.2 ± 88.9 mo. The overall improvement in the Burke-Fahn-Marsden Dystonia Rating Scale scores (movement and disability, respectively) was 57.8% and 36.4% in generalized dystonia, 60.0% and 45.8% in hemidystonia, and 65.6% and 56.8% in DT. Patients with DT showed an 83.3% improvement in mean Unified Parkinson's Disease Rating Scale tremor score. Patients with cerebral palsy showed mean improvements of 66.7% in movement scores and 50.8% in disability scores. No mortality or major morbidity was observed postoperatively.

CONCLUSION

Stereotactic radiofrequency unilateral combined thalamotomy, campotomy, and zona incerta lesions may be an effective surgical alternative for patients with dystonia, especially those with secondary dystonia resistant to deep brain stimulation.

Movement disorders

Over 30 years it has been demonstrated that Gamma Knife thalamotomy is a valuable method of treating the tremor of Parkinson's Disease and Essential Tremor. It is also effective against the tremor associated with Multiple Sclerosis. To date Gamma Knife pallidotomy has not received the acceptance of the profession.

Should the Globus Pallidus Targeting Be Refined in Dystonia?

BACKGROUND AND STUDY AIMS

 Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a highly effective therapy for primary generalized and focal dystonias, but therapeutic success is compromised by a nonresponder rate of up to 20%. Variability in electrode placement and in tissue stimulated inside the GPi may explain in part different outcomes among patients. Refinement of the target within the pallidal area could be helpful for surgery planning and clinical outcomes. The objective of this study was to discuss current and potential methodological (somatotopy, neuroimaging, and neurophysiology) aspects that might assist neurosurgical targeting of the GPi, aiming to treat generalized or focal dystonia.

METHODS

 We selected published studies by searching electronic databases and scanning the reference lists for articles that examined the anatomical and electrophysiologic aspects of the GPi in patients with idiopathic/inherited dystonia who underwent functional neurosurgical procedures.

RESULTS

 The sensorimotor sector of the GPi was the best target to treat dystonic symptoms, and was localized at its lateral posteroventral portion. The effective volume of tissue activated (VTA) to treat dystonia had a mean volume of 153 mm³ in the posterior GPi area. Initial tractography studies evaluated the close relation between the electrode localization and pallidothalamic tract to control dystonic symptoms.Regarding the somatotopy, the more ventral, lateral, and posterior areas of the GPi are associated with orofacial and cervical representation. In contrast, the more dorsal, medial, and anterior areas are associated with the lower limbs; between those areas, there is the representation of the upper limb. Excessive pallidal synchronization has a peak at the theta band of 3 to 8 Hz, which might be responsible for generating dystonic symptoms.

CONCLUSIONS

 Somatotopy assessment of posteroventral GPi contributes to target-specific GPi sectors related to segmental body symptoms. Tractography delineates GPi output pathways that might guide electrode implants, and electrophysiology might assist in pointing out areas of excessive theta synchronization. Finally, the identification of oscillatory electrophysiologic features that correlate with symptoms might enable closed-loop approaches in the future.

Specific movement and disability improvements in Burke-Fahn-Marsden Dystonia Rating Scale derived from pallidotomy in refractory patients to medical treatment

BACKGROUND

Dystonia is a movement disorder associated with significant disability and is usually refractory to medical treatment. Pallidotomy may decrease dystonic movements. The aim of this study was to quantify movement and disability improvements through Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS).

METHODS

We carried out a longitudinal clinical study in patients with refractory primary and secondary dystonia, who underwent radiofrequency (RF) unilateral and bilateral lesions on the postero-ventro-lateral globus pallidus internus (GPi), evaluating the outcomes through BFMDRS and variables as age, time of evolution, etiology, body distribution, planned target coordinates, and lesion size, during a mean follow-up time of 35.67 months.

RESULTS

Nine RF pallidotomies were performed on 6 patients, 7 right-sided and 2 left-sided; three patients were treated unilaterally for one occasion, while the others underwent 2 surgeries, including one staged bilateral procedure. Mean BFMDRS scores for movement were 38.5 preoperative and 25.5 postoperative, and for disability were 20.4 preoperative and 17.3 postoperative. We noticed improvement in movement (32.54%, p = 0.001) and disability (17.23%, p = 0.002). There was one right GPi and internal capsule (IC) infarction with contralateral hemiparesis as sequelae.

CONCLUSIONS

RF pallidotomy is an effective and accessible procedure to reduce BFMDRS scores in refractory dystonia if patients are correctly selected by severity, evolution, and disability as determining factors.

Vim stereotactic radiosurgical thalamotomy for drug-resistant idiopathic Holmes tremor: a case report

We share our experience with stereotactic gamma knife thalamotomy (GKT) for medically refractory Holmes tremor (HT). A 22-year-old patient underwent gamma knife thalamotomy at ventrointermediate nucleus for disabling HT of the right upper limb. A single 4-mm isocenter was used to target the ventral intermediate nucleus with 130 Gy radiation. At 4 months follow up, we observed 84% improvement in his Fahn-Tolosa-Marin (FTM) rating scale with significant improvement in the right upper limb dystonic tremor. There was only subtle improvement in the ataxic component of the right lower limb. At 1 year after stereotactic GKT, there was sustained neurological improvement with no side effect, We present the stereotactic GKT as a treatment modality for drug-resistant HT. Moreover, it may be considered an alternate treatment modality especially in patients reluctant or contraindicated for any invasive surgical technique. CLINICAL TRIAL REGISTRATION NUMBER: Not required.

A Scientometric Analysis of the 100 Most Cited Articles on Pallidotomy

BACKGROUND

Pallidotomy is the oldest stereotactically performed neurosurgical procedure for movement disorders. Consequently, there is a wealth of literature available on the topic.

OBJECTIVES

The aim of this analysis was to identify the top-cited articles on pallidotomy in order to discern the origins, spread, the current trends, and the future directions of this surgical procedure.

METHODS

We performed a search of the Web of Science database on 19 October 2020 using the keyword "pallidotomy." The top-100 cited articles found were arranged in descending order on the basis of citation count (CC) and citation per year (CY). Relevant conclusions were derived.

RESULTS

The 100 top-cited articles were published between 1961 and 2017, in 24 journals. The average CC and CY were 118.1 (range - 856-46) and 5.326 (range - 29.52-2.09), respectively. The 3 most prolific authors were Lang AE (Neurologist - Toronto), Lozano AM (Neurosurgeon - Toronto), and Vitek JL (Neurologist - Atlanta). The Journal of Neurosurgery published the highest number of top-cited articles [Neurology. 1960;10:61-9]. The maximum articles were from the USA. University of Toronto and Emory University were the most productive institutions.

CONCLUSIONS

Pallidotomy has gone through several ebbs and flows. Unilateral pallidotomy is currently recommended for the treatment of motor symptoms of Parkinson's disease and dystonia. The need for further research and improved technology to make the technique safer and prove its efficacy is highlighted, especially keeping in mind a large number of populations to which the prohibitively expensive deep brain stimulation is unavailable.

Safety and efficacy of unilateral and bilateral pallidotomy for primary dystonia

Objective

Ablation of the globus pallidus internus (pallidotomy) is an effective surgical intervention for dystonia. However, the current literature on the efficacy and safety of pallidotomy for dystonia is derived only from single‐case reports and small cohort studies.

Methods

We retrospectively analyzed patients with primary dystonia who underwent pallidotomy at our institution between 2014 and 2019. Neurological conditions were evaluated using the Burke‐Fahn‐Marsden Dystonia Rating Scale (BFMDRS, range: 0–120). We evaluated the total BFMDRS score and each subitem score (nine body regions) in the patients who underwent unilateral and bilateral pallidotomy before surgery and at last available follow‐up. Moreover, postoperative complications were analyzed.

Results

We found that 69 and 20 patients underwent unilateral and bilateral pallidotomy respectively. The mean age at dystonia onset was 40.4 ± 15.2 years. The mean clinical follow‐up period was 17.2 ± 11.6 months. Unilateral pallidotomy significantly improved the total BFMDRS score from 11.2 ± 14.7 preoperatively to 5.4 ± 7.6 at last available follow‐up (51.8% improvement, p < 0.001). Furthermore, there was a significant and independent improvement in all midline BFMDRS subitems, including eyes, mouth, speech/swallow, and neck, after unilateral pallidotomy. Bilateral pallidotomy significantly improved the total BFMDRS score from 14.6 ± 10.2 preoperatively to 3.8 ± 8.2 at last available follow‐up (74.0% improvement, p < 0.001). However, bilateral pallidotomy induced medically refractory parkinsonism (postural instability and gait disturbance) in five patients, dysarthria in three patients, and dysphagia in one patient.

Interpretation

Unilateral radiofrequency pallidotomy remains a viable treatment option for patients with some forms of dystonia. Bilateral pallidotomy cannot be recommended due to unacceptably high complication rates.

MR-guided focused ultrasound pallidotomy for Parkinson's disease: safety and feasibility

OBJECTIVE

Stereotactic radiofrequency pallidotomy has demonstrated improvement in motor fluctuations in patients with Parkinson's disease (PD), particularly levodopa (L-dopa)-induced dyskinesias. The authors aimed to determine whether or not unilateral pallidotomy with MR-guided focused ultrasound (MRgFUS) could safely improve Unified Dyskinesia Rating Scale (UDysRS; the primary outcome measure) scores over baseline scores in patients with PD.

METHODS

Twenty patients with PD and L-dopa responsiveness, asymmetrical motor signs, and motor fluctuations, including dyskinesias, participated in a 1-year multicenter open-label trial of unilateral MRgFUS ablation of the globus pallidus internus.

RESULTS

The sonication procedure was successfully completed in all 20 enrolled patients. MRgFUS-related adverse neurological events were generally mild and transient, including visual field deficit (n = 1), dysarthria (n = 4, 2 mild and 2 moderate), cognitive disturbance (n = 1), fine motor deficit (n = 2), and facial weakness (n = 1). Although 3 adverse events (AEs) were rated as severe (transient sonication-related pain in 2, nausea/vomiting in 1), no AE fulfilled US FDA criteria for a Serious Adverse Effect. Total UDysRS, the primary outcome measure, improved 59% after treatment (baseline mean score 36.1, 95% CI 4.88; at 3 months 14.2, 95% CI 5.72, p < 0.0001), which was sustained throughout the study (at 12 months 20.5, 95% CI 7.39, 43% improvement, p < 0.0001). The severity of motor signs on the treated side (Movement Disorder Society version of the United Parkinson's Disease Rating Scale [MDS-UPDRS] part III) in the "off" medication state also significantly improved (baseline mean score 20.0, 95% CI 2.4; at 3 months 10.6, 95% CI 1.86, 44.5% improvement, p < 0.0001; at 12 months 10.4, 95% CI 2.11, 45.2% improvement, p > 0.0001). The vast majority of patients showed a clinically meaningful level of improvement on the impairment component of the UDysRS or the motor component of the UPDRS, while 1 patient showed clinically meaningful worsening on the UPDRS at month 3.

CONCLUSIONS

This study supports the feasibility and preliminary efficacy of MRgFUS pallidotomy in the treatment of patients with PD and motor fluctuations, including dyskinesias. These preliminary data support continued investigation, and a placebo-controlled, blinded trial is in progress.Clinical trial registration no.: NCT02263885 (clinicaltrials.gov).

Bilateral Pallidotomy for Dystonia: A Systematic Review

Stereotactic lesioning of the bilateral globus pallidus (GPi) was one of the first surgical treatments for medication‐refractory dystonia but has largely been abandoned in clinical practice after the introduction of deep brain stimulation (DBS). However, some patients with dystonia are not eligible for DBS. Therefore, we reviewed the efficacy, safety, and sustainability of bilateral pallidotomy by conducting a systematic review of individual patient data (IPD). Guidelines of the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses and IPD were followed. In May 2020, Medline, Embase, Web of Science, and Cochrane Library were searched for studies reporting on outcome of bilateral pallidotomy for dystonia. If available, IPD were collected. In this systematic review, 100 patients from 33 articles were evaluated. Adverse events were reported in 20 patients (20%), of which 8 were permanent (8%). Pre‐and postoperative Burke‐Fahn‐Marsden Dystonia Rating Movement Scale scores were available for 53 patients. A clinically relevant improvement (>20%) of this score was found in 42 of 53 patients (79%). Twenty‐five patients with status dystonicus (SD) were described. In all but 2 the SD resolved after bilateral pallidotomy. Seven patients experienced a relapse of SD. Median‐reported follow‐up was 12 months (n = 83; range: 2–180 months). Based on the current literature, bilateral pallidotomy is an effective and relatively safe procedure for certain types of dystonia, particularly in medication‐refractory SD. Although due to publication bias the underreporting of negative outcomes is very likely, bilateral pallidotomy is a reasonable alternative to DBS in selected dystonia patients. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

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.

Treatment of Dystonia: Medications, Neurotoxins, Neuromodulation, and Rehabilitation

Dystonia is a complex disorder with numerous presentations occurring in isolation or in combination with other neurologic symptoms. Its treatment has been significantly improved with the advent of botulinum toxin and deep brain stimulation in recent years, though additional investigation is needed to further refine these interventions. Medications are of critical importance in forms of dopa-responsive dystonia but can be beneficial in other forms of dystonia as well. Many different rehabilitative paradigms have been studied with variable benefit. There is growing interest in noninvasive stimulation as a potential treatment, but with limited long-term benefit shown to date, and additional research is needed. This article reviews existing evidence for treatments from each of these categories. To date, there are many examples of incomplete response to available treatments, and improved therapies are needed.

Radiofrequency Ablation Through Previously Effective Deep Brain Stimulation Leads for Parkinson Disease: A Retrospective Series

BACKGROUND

Although deep brain stimulation (DBS) of the subthalamic nucleus (STN) or globus pallidus internus (GPi) is the surgical method of choice to treat the canonical symptoms of Parkinson disease, occasionally surgical sites become infected or the hardware erodes, necessitating explantation. Usual practice is to remove and reimplant replacement leads after tissue healing, leaving patients without the clinical benefits of DBS for several months, and at risk for DBS withdrawal in some, and some patients are no longer good surgical candidates for reimplantation. Radiofrequency ablation through the DBS lead is an option for these patients.

METHODS

We performed a retrospective chart review of all patients who underwent radiofrequency ablation of the STN or GPi through indwelling DBS leads performed before hardware removal at our institution. We generated patient-specific anatomic models to determine lesion locations and volumes.

RESULTS

Six patients underwent radiofrequency ablation of the STN (n = 4) and GPi (n = 2) through indwelling DBS leads. All 6 of these patients initially showed comparable motor symptom relief to that experienced with DBS before lesioning, with 4 patients sustaining meaningful long-term (≥2 years) improvement. Better outcomes were achieved in those patients with a higher percentage of the planned target lesioned.

CONCLUSIONS

Radiofrequency ablation through indwelling DBS leads before explantation could be considered a viable alternative to subsequent reimplantation or stereotactic lesion in patients with Parkinson disease in whom hardware explantation is necessary, if the patient achieved substantive symptom relief with DBS. This approach avoids symptom exacerbation while awaiting revision surgery.

Unilateral pallidotomy as a potential rescue therapy for cervical dystonia after unsatisfactory selective peripheral denervation

OBJECTIVE

Selective peripheral denervation (SPD) is a widely accepted surgery for medically refractory cervical dystonia (CD), but when SPD has failed, the available approaches are limited. The authors investigated the results from a cohort of CD patients treated with unilateral pallidotomy after unsatisfactory SPD.

METHODS

The authors retrospectively analyzed patients with primary CD who underwent unilateral pallidotomy after SPD between April 2007 and August 2019. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) was used to evaluate symptom severity before surgery, 7 days postsurgery, 3 months postsurgery, and at the last follow-up. TWSTRS subscores for disability and pain and the 24-item Craniocervical Dystonia Questionnaire (CDQ-24) were used to assess quality of life.

RESULTS

At a mean final follow-up of 5 years, TWSTRS severity subscores and total scores were significantly improved (n = 12, mean improvement 57.3% and 62.3%, respectively, p = 0.0022 and p = 0.0022), and 8 of 12 patients (66.7%) were characterized as responders (improvement ≥ 25%). Patients with rotation symptoms before pallidotomy showed greater improvement in TWSTRS severity subscores than those who did not (p = 0.049). The most common adverse event was mild upper-limb weakness (n = 3). Patients' quality of life was also improved.

CONCLUSIONS

Unilateral pallidotomy seems to offer an effective and safe option for patients with CD who have otherwise experienced limited benefits from SPD.

Gamma Knife Radiosurgical Pallidotomy for Dystonia: Not a Fallen Angel

The authors report a case of successful management of right side hemidystonia with gamma knife radiosurgery. A 24-year-old male with a history of birth asphyxia subsequently developed worsening right-sided torsional hemidystonia which failed to respond to the medical management. MRI of the brain was unremarkable. Stereotactic gamma knife radiosurgery (GKRS) was performed to create a lesion in the left posteroventral globus pallidum. The patient gradually improved over a course of 18 months without any complication. He obtained 61% improvement in dystonia rating scale. Radiosurgical pallidotomy is often viewed with suspicion and functional neurosurgeons show reluctance in preferring it to stereotactic radio frequency lesioning or stimulation surgery. The authors would like to highlight the chances of not only control, but also cure of the disease with this cost-effective treatment modality.

Ablative brain surgery: an overview

Background: Ablative therapies have been used for the treatment of neurological disorders for many years. They have been used both for creating therapeutic lesions within dysfunctional brain circuits and to destroy intracranial tumors and space-occupying masses. Despite the introduction of new effective drugs and neuromodulative techniques, which became more popular and subsequently caused brain ablation techniques to fall out favor, recent technological advances have led to the resurgence of lesioning with an improved safety profile. Currently, the four main ablative techniques that are used for ablative brain surgery are radiofrequency thermoablation, stereotactic radiosurgery, laser interstitial thermal therapy and magnetic resonance-guided focused ultrasound thermal ablation. Object: To review the physical principles underlying brain ablative therapies and to describe their use for neurological disorders. Methods: The literature regarding the neurosurgical applications of brain ablative therapies has been reviewed. Results: Ablative treatments have been used for several neurological disorders, including movement disorders, psychiatric disorders, chronic pain, drug-resistant epilepsy and brain tumors. Conclusions: There are several ongoing efforts to use novel ablative therapies directed towards the brain. The recent development of techniques that allow for precise targeting, accurate delivery of thermal doses and real-time visualization of induced tissue damage during the procedure have resulted in novel techniques for cerebral ablation such as magnetic resonance-guided focused ultrasound or laser interstitial thermal therapy. However, older techniques such as radiofrequency thermal ablation or stereotactic radiosurgery still have a pivotal role in the management of a variety of neurological disorders.

Modifying the progression of Alzheimer's and Parkinson's disease with deep brain stimulation

At times of an aging population and increasing prevalence of neurodegenerative disorders, effective medical treatments remain limited. Therefore, there is an urgent need for new therapies to treat Alzheimer's disease (AD). Deep brain stimulation (DBS) is thought to address the neuronal network dysfunction of this disorder and may offer new therapeutic options. Preliminary evidence suggests that DBS of the fornix may have effects on cognitive decline, brain glucose metabolism, hippocampal volume and cortical grey matter volume in certain patients with mild AD. Rodent studies have shown that increase of cholinergic neurotransmitters, hippocampal neurogenesis, synaptic plasticity and reduction of amyloid plaques are associated with DBS. Currently a large phase III study of fornix DBS is assessing efficacy in patients with mild AD aged 65 years and older. The Nucleus basalis of Meynert has also been explored in a phase I study in of mild to moderate AD and was tolerated well regardless of the lack of benefit. Being an established therapy for Parkinson's Disease (PD), DBS may exert some disease-modifying traits rather than being a purely symptomatic treatment. There is evidence of dopaminergic neuroprotection in animal models and some suggestion that DBS may influence the natural progression of the disorder. Neuromodulation may possibly have beneficial effects on course of different neurodegenerative disorders compared to medical therapy alone. For dementias, functional neurosurgery may provide an adjunctive option in patient care. This article is part of the special issue entitled 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

The role of high-intensity focused ultrasound as a symptomatic treatment for Parkinson's disease

MR-guided focused ultrasound is a novel, minimally invasive surgical procedure for symptomatic treatment of PD. With this technology, the ventral intermediate nucleus, STN, and internal globus pallidus have been targeted for therapeutic cerebral ablation, while also minimizing the risk of hemorrhage and infection from more invasive neurosurgical procedures. In a double-blinded, prospective, sham-controlled randomized controlled trial of MR-guided focused ultrasound thalamotomy for treatment of tremor-dominant PD, 62% of treated patients demonstrated improvement in tremor scores from baseline to 3 months postoperatively, as compared to 22% in the sham group. There has been only one open-label trial of MR-guided focused ultrasound subthalamotomy for patients with PD, demonstrating improvements of 71% for rigidity, 36% for akinesia, and 77% for tremor 6 months after treatment. Among the two open-label trials of MR-guided focused ultrasound pallidotomy for patients with PD, dyskinesia and overall motor scores improved up to 52% and 45% at 6 months postoperatively. Although MR-guided focused ultrasound thalamotomy is now approved by the U.S. Food and Drug Administration for treatment of parkinsonian tremor, additional high-quality randomized controlled trials are warranted and are underway to determine the safety and efficacy of MR-guided focused ultrasound subthalamotomy and pallidotomy for treatment of the cardinal features of PD. These studies will be paramount to aid clinicians to determine the ideal ablative target for individual patients. Additional work will be required to assess the durability of MR-guided focused ultrasound lesions, ideal timing of MR-guided focused ultrasound ablation in the course of PD, and the safety of performing bilateral lesions. © 2019 International Parkinson and Movement Disorder Society.

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.

[Unilateral posteroventral pallidotomy in the treatment of drug-induced dyskinesia in Parkinson's disease]

OBJECTIVE

to determine the efficacy of unilateral posteroventral pallidotomy (PVP) in the treatment of drug-induced dyskinesia (DID) in Parkinson's disease (PD).

MATERIAL AND METHODS

We analyzed surgical treatment of 14 patients with PD complicated by DID who underwent unilateral PVP at the Research Center of Neurology in the period between 2012 and 2015. The clinical type of DID was mainly represented by peak-dose choreoathetoid dyskinesia, more pronounced in the distal limbs, and predominantly unilateral. The severity of drug-induced dyskinesia was assessed on the UPDRS scale (part IV-A) before surgery and at 1 week and 6 months after surgery.

RESULTS

One week after pallidotomy, all of the 14 patients had a regression of contralateral dyskinesia by 68.3±9.7%; 50% of patients had a regression of ipsilateral dyskinesias by 43%, on average. In 50% of cases, the dose of levodopa was reduced by 15%, on average. On examination at 6 months after surgery, regression of contralateral dyskinesia was 55.7±8.8%, and the severity of ipsilateral DID returned to the preoperative level. The use of pallidotomy significantly improved the indicators of daily activity and quality of life of patients. There were no significant postoperative complications. Three patients had mild speech disorders in the form of dysarthria, which regressed 2-3 weeks after surgery.

Staged pallidotomy: MRI and clinical follow-up in status dystonicus

PURPOSE

We report on a patient affected by Status Distonicus who was treated with Deep Brain Stimulation electrodes implanted in the Globus Pallidus internus (Gpi) and used for serial radiofrequency lesions.

MATERIALS AND METHODS

The evolution of radiofrequency lesions was monitored by post-operative and late Magnetic Resonance Imaging (MRI). After the first lesion the patient did improve, though not in a significant fashion. Therefore, three further radiofrequency lesions were delivered 2, 4 and 6 days respectively after surgery with subsequent improvement of dystonic movements.

RESULTS

MRI scans performed at 8 days, 3 months, and 6 months after surgery showed a diffuse T2-hyperintense and T1-hypointense GPi signal alteration which progressively decreased over time.

CONCLUSION

We confirm that the possibility to stage pallidotomies over time using a couple of new contacts is a safe and efficacious procedure in treating SD patients where the lesions themselves are limited by the appearance of side effects, or in patients showing a poor response to a single lesion. As far as we know, this is the first description of MRI evolution and monitoring of a staged pallidotomy.

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.

Seventy Years with the Globus Pallidus: Pallidal Surgery for Movement Disorders Between 1947 and 2017

The year 2017 marks the 70th anniversary of the birth of human stereotactic neurosurgery. The first procedure was a pallidotomy for Huntington's disease. However, it was for Parkinson's disease that pallidotomy was soon adopted worldwide. Pallidotomy was abandoned in the late 1950s in favor of thalamotomy because of the latter's more striking effect on tremor. The advent of levodopa put a halt to all surgery for PD. In the mid-1980s, Laitinen reintroduced the posteroventral pallidotomy of Leksell, and this procedure spread worldwide thanks to its efficacy on most parkinsonian symptoms including levodopa-induced dyskinesias and thanks to basic scientific work confirming the role of the globus pallidus internus in the pathophysiology of PD. With the advent of deep brain stimulation of the subthalamic nucleus, pallidotomy was again abandoned, and even DBS of the GPi has been overshadowed by STN DBS. The GPi reemerged in the late 1990s as a major stereotactic target for DBS in dystonia and, recently, in Tourette syndrome. Lately, lesioning of the GPI is being proposed to treat refractory status dystonicus or to treat DBS withdrawal syndrome in PD patients. Hence, the pallidum as a stereotactic target for either lesioning or DBS has been the phoenix of functional stereotactic neurosurgery, constantly abandoned and then rising again from its ashes. This review is a tribute to the pallidum on its 70th anniversary as a surgical target for movement disorders, analyzing its ebbs and flows and highlighting its merits, its versatility, and its resilience. © 2017 International Parkinson and Movement Disorder Society.

My 25 Stimulating Years with DBS in Parkinson's Disease

The year 2017 marks the 30th anniversary of the birth of modern deep brain stimulation (DBS), which was introduced by Benabid, Pollak et al. in 1987, initially targeting the motor thalamus to treat tremor, and subsequently targeting the subthalamic nucleus (STN) for treatment of symptoms of advanced Parkinson's disease (PD). STN DBS is undoubtedly "the most important discovery since levodopa", as stated by David Marsden in 1994. In 2014, The Lasker- DeBakey Clinical Medical Research Award to "honor two scientists who developed deep brain stimulation of the subthalamic nucleus", was bestowed upon Benabid and DeLong. STN DBS remains today the main surgical procedure for PD, due to its effectiveness in ameliorating PD symptoms and because it is the only surgical procedure for PD that allows a radical decrease in medication. Future improvements of DBS include the possibility to deliver a "closed-loop", "on demand" stimulation, as highly preliminary studies suggest that it may improve both axial and appendicular symptoms and reduce side effects such as dysarthria. Even though DBS of the subthalamic nucleus is the main surgical procedure used today for patients with PD, all patients are not suitable for STN DBS; as a functional neurosurgeon performing since more than 25 years various surgical procedures the aim of which is not to save life but to improve the patient's quality of life, I consider that the surgery should be tailored to the patient's individual symptoms and needs, and that its safety is paramount.

Historical developments in children's deep brain stimulation

BACKGROUND

Heterogeneous by the underlying pathobiology and clinical presentation, childhood onset dystonia is most frequently progressive, with related disability and limitations in functions of daily living. Consequently, there is an obvious need for efficient symptomatic therapies.

METHODS AND RESULTS

Following lesional surgery to basal ganglia (BG) and thalamus, deep brain stimulation (DBS) is a more conservative and adjustable intervention to and validated for internal segment of the globus pallidus (GPi), highly efficient in treating isolated "primary" dystonia and associated symptoms such as subcortical myoclonus. The role of DBS in acquired, neurometabolic and degenerative disorders with dystonia deserves further exploration to confirm as an efficient and lasting therapy. However, the pathobiological background with distribution of the sequellae over the central nervous system and related clinical features, will limit DBS efficacy in these conditions. Cumulative arguments propose DBS in severe life threatening dystonic conditions called status dystonicus as first line therapy, irrespective of the underlying cause. There are no currently available validated selection criteria for DBS in pediatric dystonia. Concurrent targets such as subthalamic nucleus (STN) and several motor nuclei of the thalamus are under exploration and only little information is available in children. DBS programming in paediatric population was adopted from experience in adults. The choice of neuromodulatory DBS parameters could influence not only the initial therapeutic outcome of dystonic symptoms but also its maintenance over time and potentially the occurrence of DBS related side effects.

CONCLUSION

DBS allows efficient symptomatic treatment of severe dystonia in children and advances pathophysiological knowledge about local and distributed abnormal neural activity over the motor cortical-subcortical networks in dystonia and other movement disorders.

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.