Simultaneous bilateral pallidoansotomy for idiopathic dystonia musculorum deformans

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.

Neuromodulation in Dystonia - Harnessing the Network

Adult-onset isolated focal dystonia (AOIFD) is a network disorder characterised by abnormalities of sensory processing and motor control. These network abnormalities give rise to both the phenomenology of dystonia and the epiphenomena of altered plasticity and loss of intracortical inhibition. Existing modalities of deep brain stimulation effectively modulate parts of this network but are limited both in terms of targets and invasiveness. Novel approaches using a variety of non-invasive neuromodulation techniques including transcranial stimulation and peripheral stimulation present an interesting alternative approach and may, in conjunction with rehabilitative strategies, have a role in tailored therapies targeting the underlying network abnormality behind AOIFD.

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.

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.

A Stepwise Approach: Decreasing Infection in Deep Brain Stimulation for Childhood Dystonic Cerebral Palsy

Dystonia is a movement disorder characterized by involuntary muscle contractions, which cause twisting movements or abnormal postures. Deep brain stimulation has been used to improve the quality of life for secondary dystonia caused by cerebral palsy. Despite being a viable treatment option for childhood dystonic cerebral palsy, deep brain stimulation is associated with a high rate of infection in children. The authors present a small series of patients with dystonic cerebral palsy who underwent a stepwise approach for bilateral globus pallidus interna deep brain stimulation placement in order to decrease the rate of infection. Four children with dystonic cerebral palsy who underwent a total of 13 surgical procedures (electrode and battery placement) were identified via a retrospective review. There were zero postoperative infections. Using a multistaged surgical plan for pediatric patients with dystonic cerebral palsy undergoing deep brain stimulation may help to reduce the risk of infection.

Strategies for treatment of dystonia

Treatment of dystonias is generally symptomatic. To produce sufficient therapy effects, therefore, frequently a multimodal and interdisciplinary therapeutic approach becomes necessary, combining botulinum toxin therapy, deep brain stimulation, oral antidystonic drugs, adjuvant drugs and rehabilitation therapy including physiotherapy, occupational therapy, re-training, speech therapy, psychotherapy and sociotherapy. This review presents the recommendations of the IAB-Interdisciplinary Working Group for Movement Disorders Special Task Force on Interdisciplinary Treatment of Dystonia. It reviews the different therapeutic modalities and outlines a strategy to adapt them to the dystonia localisation and severity of the individual patient. Hints to emerging and future therapies will be given.

Pallidal Deep Brain Stimulation in Cervical Dystonia: Clinical Outcome in Four Cases

Objective:

Report on the clinical results following bilateral globus pallidus interna deep brain stimulation in four patients (one female and three males) with severe cervical dystonia, mean age 48 years (range 37-67).

Methods:

All four patients had failed extensive medical and botulinum toxin treatment. The mean duration of the disease was nine years (range 4-15 years). Patients were assessed pre and postoperatively using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Preoperatively, the mean TWSTRS total score was 43.2 (range 28-60.5). Posteroventral pallidal deep brain stimulators were inserted using MRI and microelectrode recording guidance. Last follow-up was 15 months for the four patients.

Results:

Mean reduction in the TWSTRS total scores at last follow- up was 73% (range 61- 85%). Improvement in pain occurred soon after deep brain stimulation surgery. Motor improvement was delayed and prolonged over several months. Frequent adjustment in the stimulation parameters was necessary in the first three months.

Conclusion:

Bilateral pallidal stimulation is effective in management of selected cases of intractable cervical dystonia.

What's new in surgical treatment for dystonia?

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

Tolerance of early pallidal stimulation in pediatric generalized dystonia

The authors report on 2 cases of pediatric generalized dystonia with a DYT1 mutation; the patients, an 11-year-old girl and a 9-year-old boy, underwent chronic, pallidal deep brain stimulation (DBS) of the globus pallidus internus (GPi). The dystonic postures in both cases showed dramatic improvements with pallidal DBS, but each patient's symptoms gradually recurred within a year, irrespective of exhaustive readjustments of the stimulation settings. After the recurrence of the dystonic symptoms, the DBS leads were replaced within the GPi in one patient (Case 1) and additional DBS leads were implanted into the bilateral subthalamic nuclei in the other patient (Case 2). Neither measure produced any further clinical benefit, and the patient in Case 2 died of status dystonicus 2 days after reoperation. These findings suggest that early pallidal DBS for pediatric dystonia is indeed effective, although there are some cases in which its therapeutic effect is lost. One possible reason may be the ability of the preadolescent brain to tolerate chronic electrical stimuli during the active maturation process.

Deep brain stimulation in children and young adults with secondary dystonia: the Children's Hospital Los Angeles experience

Background

Dystonia is a movement disorder in which involuntary sustained or intermittent muscle contractions cause twisting and repetitive movements, abnormal postures, or both. It can be classified as primary or secondary. There is no cure for dystonia and the goal of treatment is to provide a better quality of life for the patient.

Surgical intervention is considered for patients in whom an adequate trial of medical treatment has failed. Deep brain stimulation (DBS), specifically of the globus pallidus interna (GPi), has been shown to be extremely effective in primary generalized dystonia. There is much less evidence for the use of DBS in patients with secondary dystonia. However, given the large number of patients with secondary dystonia, the significant burden on the patients and their families, and the potential for DBS to improve their functional status and comfort level, it is important to continue to investigate the use of DBS in the realm of secondary dystonia.

Object

The objective of this study is to review a series of cases involving patients with secondary dystonia who have been treated with pallidal DBS.

Methods

A retrospective review of 9 patients with secondary dystonia who received treatment with DBS between February 2011 and February 2013 was performed. Preoperative and postoperative videos were scored using the Barry-Albright Dystonia Scale (BADS) and Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) by a neurologist specializing in movement disorders. In addition, the patients' families completed a subjective questionnaire to assess the perceived benefit of DBS.

Results

The average age at DBS unit implantation was 15.1 years (range 6–20 years). The average time to follow-up for the BADS evaluation from battery implantation was 3.8 months (median 3 months). The average time to follow-up for the subjective benefit evaluation was 10.6 months (median 9.5 months). The mean BADS scores improved by 9% from 26.5 to 24 (p = 0.04), and the mean BFMDRS scores improved by 9.3% (p = 0.055). Of note, even in patients with minimal functional improvement, there seemed to be decreased contractures and spasms leading to improved comfort. There were no complications such as infections or hematoma in this case series. In the subjective benefit evaluation, 3 patients' families reported “good” benefit, 4 reported “minimal” benefit, and 1 reported no benefit.

Conclusions

These early results of GPi stimulation in a series of 9 patients suggest that DBS is useful in the treatment of secondary generalized dystonia in children and young adults. Objective improvements in BADS and BFMDRS scores are demonstrated in some patients with generalized secondary dystonia but not in others. Larger follow-up studies of DBS for secondary dystonia, focusing on patient age, history, etiology, and patterns of dystonia, are needed to learn which patients will respond best to DBS.

Functional neurosurgery for secondary dystonia: indications and long-term results

Dystonia is a movement disorder characterized by patterned, repetitive, phasic, or tonic sustained muscle contractions that produce abnormal, often twisting, postures or repetitive movements. When the disorder is genetic or the cause is unknown and dystonia is the sole feature, the disease is called primary or idiopathic, conversely secondary dystonia (SD) may be caused by various brain insults. Both primary dystonia and SD have been notorious for their poor response to medical treatment. Today, stereotactic neurosurgical procedures are offered to improve the disability and quality of life of patients who do not respond to medical therapy. However, SD shows less and more variable results than primary dystonia to neurosurgical procedures, the benefits of ablative or deep brain stimulation (DBS) procedures in basal structures being still subject to debate and much harder to fully appreciate. In this work, the authors show a 33-patient series with secondary dystonia, separating the statistic and clinical analysis into several etiology groups: perinatal insults, tardive syndromes, genetic syndromes, and posttraumatic. In these groups, we show the mean BFM score improvement in the different patient series, comparing our results with world literature, and finally propose a classification system for bettering the clinical approach in surgery decision when this is indicated.

The effect of bilateral globus pallidus internus deep brain stimulation plus ventralis oralis thalamotomy on patients with cerebral palsy

OBJECTIVE

We compared bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) with bilateral GPi DBS plus ventralis oralis (Vo) thalamotomy to analyze the effect of the combined Vo thalamotomy.

METHODS

Between March 2003 and December 2008, 10 patients underwent DBS and/or Vo thalamotomy for treatment of cerebral palsy in our institute of neurosurgery and rehabilitation medicine. Four patients received bilateral posteroventral GPi DBS as group I and 6 patients received GPi DBS plus unilateral thalamotomy as group II.

RESULTS

The movement and disability scores of group I improved by 32 and 14.3%, respectively, at the last follow-up compared with baseline. The movement and disability scores of group II improved by 31.5 and 0.18%. The BFMDRS-movement subscores of group II demonstrated statistically significant improvement in the contralateral arm compared to group I (p = 0.042). Body pain, vitality and mental health seemed to improve in group II, in terms of health-related quality of life.

CONCLUSIONS

Contrary to our expectations, we were unable to demonstrate clear improvements in overall BFMDRS scores between group I and group II. However, movements of the contralateral upper extremities improved and health-related quality of life in group II showed satisfactory results.

Current and future medical treatment in primary dystonia

Dystonia is a hyperkinetic movement disorder, characterized by involuntary and sustained contractions of opposing muscles causing twisting movements and abnormal postures. It is often a disabling disorder that has a significant impact on physical and psychosocial wellbeing. The medical therapeutic armamentarium used in practice is quite extensive, but for many of these interventions formal proof of efficacy is lacking. Exceptions are the use of botulinum toxin in patients with cervical dystonia, some forms of cranial dystonia (in particular, blepharospasm) and writer's cramp; deep brain stimulation of the pallidum in generalized and segmental dystonia; and high-dose trihexyphenidyl in young patients with segmental and generalized dystonia. In order to move this field forward, we not only need better trials that examine the effect of current treatment interventions, but also a further understanding of the pathophysiology of dystonia as a first step to design and test new therapies that are targeted at the underlying biologic and neurophysiologic mechanisms.

The long-term surgical outcomes of secondary hemidystonia associated with post-traumatic brain injury

BACKGROUND

The aim was to assess the effect of deep brain stimulation for secondary hemidystonias associated with focal post-traumatic brain injuries.

METHODS

Four patients underwent deep brain stimulation for the treatment of medically refractory secondary hemidystonia associated with post-traumatic brain injury. Clinical outcome assessments were based on Burke-Fahn-Marsden Dystonia Rating Scale movement and disability scores. Health-related quality of life was assessed using a 36-item short-form general health survey questionnaire administered preoperatively and at the last follow-up visit.

RESULTS

Burke-Fahn-Marsden Dystonia Rating Scale movement scores had improved by 73.2% (range, 38.1-94.1) and disability scores had improved by 75% (range, 60-100) at the 2-year follow-up visit. The health-related quality of life assessment revealed satisfactory results at follow-up, such that body pain, general health, vitality, social functioning, as well as emotional and mental health improved significantly.

CONCLUSIONS

Globus pallidus internus deep brain stimulation can be used to modulate and ameliorate secondary hemidystonia associated with focal post-traumatic brain injury.

Treatment of secondary dystonia with a combined stereotactic procedure: long-term surgical outcomes

OBJECTIVE

There is some debate about the effects of pallidal deep brain stimulation (DBS) or lesioning on secondary dystonia. We applied a multimodal method to maximize the treatment effects of deep brain stimulation in patients with secondary dystonia.

METHODS

Between March 2003 and January 2009, four patients underwent bilateral globus pallidus internus (GPi) DBS and six patients underwent bilateral GPi DBS plus unilateral thalamotomy for treatment of cerebral palsy (CP). Among the patients with secondary dystonia without CP, five were also treated by DBS. We classified patients with generalized secondary dystonia with cerebral palsy into group I and patients with focal dystonia without CP into group II. Clinical outcome assessments were based on Burke-Fahn-Marsden Dystonia Rating Scale movement and disability scores. Heath-related quality of life was assessed with a 36-item short-form general health survey questionnaire preoperatively and at the last follow-up.

RESULTS

The movement and disability scores of group I-A had improved by 32.0% (P = 0.285) and 14.3% (P = 0.593), respectively, at the last follow-up compared with baseline. The movement and disability scores of group I-B had improved by 31.5% and 0.18% at the last follow-up compared with baseline, respectively. In comparison with patients in group I-A, patients in group I-B showed a significant improvement in movement scores for the contralateral arm (P = 0.042). Group II patients showed a marked improvement in movement and disability scores of 77.7% (P = 0.039) and 80.0% (P = 0.041), respectively.

CONCLUSIONS

We demonstrated that DBS plus unilateral ventralis oralis thalamotomy for CP patients with fixed states in the upper extremities is useful not only to treat secondary dystonic movement but also to improve quality of life. In group II patients with post-traumatic dystonia and tardive dyskinesia, we achieved excellent clinical outcomes using a stereotactic procedure.

Chronic bilateral pallidal stimulation in patients with generalized primary dystonia - multi-contact cathodal stimulation is superior to bipolar stimulation mode. Preliminary results

BACKGROUND AND PURPOSE

Primary generalized dystonia (PGD) is a medically refractory progressive disease of the brain causing near total handicap of affected patients. The aim of the study was to assess the efficacy and safety of bilateral pallidal stimulation in patients with PGD.

MATERIAL AND METHODS

The study population is composed of 5 patients with PGD. The formal objective assessment included the Burke-Fahn-Marsden dystonia rating scale (BFMDRS). All stereotactic procedures were performed in general anaesthesia using a Leksell G stereotactic head frame without electrophysiological guidance. Immediately after insertion of deep brain stimulation (DBS) leads, the internal pulse generators (Itrel II or Soletra) were implanted subcutaneously in the chest wall or abdominal region.

RESULTS

There were no complications related to the stereotactic procedures. The hardware-related complications (two broken DBS leads) were replaced successfully. There were no infections or erosions of implanted hardware. It has been observed that in the long-term follow-up period primary set bipolar stimulation mode lost its benefit achieved previously. Various stimulation combinations were investigated. Monopolar cathodal or especially multi-contact cathodal stimulation was the most effective one. The efficacy of bilateral pallidal stimulation was proved by the objective validated BFMDRS at long-term follow-up.

CONCLUSIONS

Response to DBS may improve with the number of activated cathodal contacts within the globus pallidus internus.

Dystonia and the role of deep brain stimulation

Dystonia is a painful, disabling disease whose cause in many cases remains unknown. It has historically been treated with a variety methodologies including baclofen pumps, Botox injection, peripheral denervation, and stereotactic surgery. Deep brain stimulation (DBS) is emerging as a viable treatment option for selected patients with dystonia. Results of DBS for dystonia appear to be more consistently superior in patients with primary versus secondary forms of the disorder. Patients with secondary dystonia, due to a variety of causes, may still be candidates for DBS surgery, although the results may not be as consistently good. The procedure is relatively safe with a small likelihood of morbidity and mortality. A randomized trial is needed to determine who are the best patients and when it is best to proceed with surgery.

Dystonia: a surgeon's perspective

Surgery for dystonia has a history stretching back for centuries including myotomy and other procedures on the musculoskeletal system. In the last century lesional procedures, mainly involving the pallidum became popular. More recently, with the advent of deep brain stimulation, bilateral medial pallidal stimulation has become commonplace. This review describes the issues with patient selection, technical aspects of implantation and effects as well as complications of the technique. Some of the rarer types of dystonia that have also been treated with DBS are also described.

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

Fifteen years after its resurrection, pallidotomy for Parkinson's disease (PD) and dystonia has once again been supplanted, this time by deep brain stimulation (DBS). Did this occur because pallidotomy was not effective or safe, or because DBS was found to be more effective and safer? This review focuses on the evidence-and its quality-supporting the effectiveness and safety of pallidotomy for PD and dystonia, and the comparative effectiveness and safety of DBS of the subthalamic nucleus (STN) and globus pallidus pars interna (GPi). Discussed first are the determinants of "level 1" recommendations, including the confounding effects on interpretation of randomized clinical trials (RCTs) that fail to control for patient bias (i.e., placebo effects). Although several RCTs have been performed comparing unilateral pallidotomy to medical therapy, GPi DBS, or STN DBS for PD, none controlled for patient bias. Comparison of these trials to estimate the placebo effect, and examination of retrospective case series, suggests that the true effectiveness of unilateral pallidotomy is 20% to 30% reduction of 'off' total motor UPDRS scores, which is similar to the effects of unilateral GPi DBS or STN DBS, but less than bilateral STN DBS. At experienced centers, safety of unilateral pallidotomy appears equivalent to unilateral DBS, but bilateral DBS is likely safer than bilateral pallidotomy. Whereas there have been no RCTs of pallidotomy for dystonia, two double-blind, sham-controlled RCTs of bilateral GPi DBS were performed. Nevertheless, limited uncontrolled series suggest that bilateral pallidotomy is similar to GPi DBS in effectiveness and safety for dystonia. Thus, pallidotomy was not rejected because of lack of effectiveness or safety, and it remains a viable alternative in situations where DBS is not available or not feasible.

The treatment of movement disorders by deep brain stimulation

It has been understood, for some time, that modulation of deep brain nuclei within the basal ganglia and thalamus can have a therapeutic effect in patients with movement disorders. Because of its reversibility and adjustability, deep brain stimulation (DBS) has largely come to replace traditional ablation procedures. The clinical effects of DBS vary, depending both on the target being stimulated and on the parameters of stimulation. Both aspects are currently the subject of substantial research and discovery. The most common targets for DBS treatment include the subthalamic nucleus for the treatment of advanced Parkinson's disease, the ventral intermediate nucleus of the thalamus for the treatment of medically refractory essential tremor, and the globus pallidus interna for the treatment of both cervical and generalized dystonias and Parkinson's disease. We review the current indications, targets, outcomes, and general procedure of DBS for essential tremor, Parkinson's disease, and dystonia.

Subthalamic nucleus stimulation for primary dystonia and tardive dystonia

With the renaissance of stereotactic pallidotomy for Parkinson's disease in 1990s, pallidotomy has become increasingly used as an effective treatment for various manifestations of medically refractory dystonia. More recently, deep brain stimulation of globus pallidus internus (GPi) has been replacing pallidotomy. Although GPi DBS has great promise for treating dystonia, there are some disadvantages. We introduce our experiences in subthalamic nucleus (STN) DBS for primary dystonia and tardive dystonia in this chapter. We propose that STN DBS has the following advantages over GPi DBS: (1) symptomatic improvement is seen immediately after stimulation, allowing us to quickly select the most suitable stimulation parameters; (2) the stimulation parameters for the STN are lower than those used for the GPi, resulting in longer battery life; and (3) STN DBS results in better symptomatic control than GPi DBS in dystonia patients when our STN data is compared to that obtained by others with using the GPi as the target. We suggest that STN DBS may be the most appropriate surgical technique for dystonia.

Deep brain stimulation of globus pallidus internus for dystonia

Neuromodulation is the functional modification of neural structures through the use of electrical stimulation. Its most clinically applicable use is deep brain stimulation (DBS) of basal ganglia structures in Parkinson's disease (PD) and essential tremor (ET). More recently, it has been used as a means of treating dystonic movement disorders. The main target of DBS for dystonia is the posteroventral globus pallidus internus (GPi), although the thalamus has been used as an alternate target in a minority of cases. In comparison to the effects seen in PD, the improvement in dystonic postures appear to differ in several ways--delay of clinical benefit, higher voltage requirements, and varied stimulator settings. In this review, the authors discuss the clinical characteristics, pathophysiology, microelectrode recording (MER) signatures, optimal surgical targets, programming parameters and outcomes in dystonia.

Treatment of dystonia

Dystonia may be a sign or symptom, that is comprised of complex abnormal and dynamic movements of different etiologies. A specific cause is identified in approximately 28% of patients, which only occasionally results in specific treatment. In most cases, treatment is symptomatic and designed to relieve involuntary movements, improve posture and function and reduce associated pain. Therapeutic options are dictated by clinical assessment of the topography of dystonia, severity of abnormal movements, functional impairment and progression of disease and consists of pharmacological, surgical and supportive approaches. Several advances have been made in treatment with newer medications, availability of different forms of botulinum toxin and globus pallidus deep brain stimulation (DBS). For patients with childhood-onset dystonia, the majority of whom later develop generalized dystonia, oral medication is the mainstay of therapy. Recently, DBS has emerged as an effective alternative therapy. Botulinum toxin is usually the treatment of choice for those with adult-onset primary dystonia in which dystonia usually remains focal. In patients with secondary dystonia, treatment is challenging and efficacy is typically incomplete and partially limited by side effects. Despite these treatment options, many patients with dystonia experience only partial benefit and continue to suffer significant disability. Therefore, more research is needed to better understand the underlying cause and pathophysiology of dystonia and to explore newer medications and surgical techniques for its treatment.

Destructive stereotactic surgery for treatment of dystonia

BACKGROUND

This study is a retrospective review of the results of stereotactic destructive surgery in selected cases of drug-resistant dystonia.

METHODS

Fifty-eight patients with drug-resistant dystonia were treated with stereotactic surgery between 1991 and 1999 in our institution. These patients' charts were retrospectively analyzed. The timing of the conducted evaluations was as follows: preoperatively, postoperatively, in the postoperative 1st week, 6th month, 12th month, and also thereafter every year.

RESULTS

Symptoms of dystonia occurred before the age of 10 years in 30 patients (51.8%) and after the age of 10 years in 28 patients (48.2%). Generalized dystonia was detected in 41 patients, whereas 11 patients had hemidystonia, 5 patients had focal dystonia, and 1 patient had segmental dystonia. The most common etiologic factor was CP (n = 34). A total of 103 ablative lesions were created in 86 surgical sessions. Thalamotomy, pallidotomy, subthalamotomy, and the region of Forel lesions were performed either separately or in combination. In this series, the mean follow-up time was 102.2 months. Except for 2 cases of temporary hemiparesis, no other complications were observed. Minor improvement was obtained in 17 patients (19.7%), improvement of a medium degree was obtained in 17 patients (19.7%), high-degree improvement was obtained in 11 (12.8%), and very high degree improvement was obtained in 16 (18.6%) patients. A final evaluation revealed permanent improvement in 32 patients (55.2%).

CONCLUSION

Production of stereotactic destructive lesions in certain specified targets is a safe method that improves quality of life and aids ambulation in patients with dystonia resistant to medical therapy.

Pallidal stimulation for dystonia

OBJECTIVE

High-frequency deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a new and promising treatment option for severe dystonia. Yet only few studies have been published to date regarding this treatment. We present the results of DBS of the GPi in 17 patients with severe dystonia of different causes.

METHODS

In our study, we included 10 patients with primary generalized dystonia, six patients with secondary generalized dystonia, and one patient with a severe dystonic cervical tremor. In all patients, DBS electrodes were implanted bilaterally within the GPi. Mean follow-up time was 36 months (range, 12-66 mo). Preoperative and postoperative evaluations (at least annually) were performed using the Burk-Fahn-Marsden scale.

RESULTS

The best improvement was achieved in patients with DYT1-positive dystonia. Patients with DYT1-negative generalized dystonia showed inhomogeneous results. There was no significant change in patients with tardive dystonia. One case of Hallervorden-Spatz disease improved dramatically within the first 2 years. The improvement in the cervical dystonic tremor was disappointing, however. Three years after DBS implantation, we found a secondary worsening of symptoms in one patient with a DYT1-positive dystonia and in the patient with Hallervorden-Spatz disease.

CONCLUSION

DBS of the GPi is a new and promising treatment option for dystonia. Secondary worsening may limit this therapy.

Neuronal activity in the basal ganglia and thalamus in patients with dystonia

OBJECTIVE

To explore the role of abnormal neuronal activity in the basal ganglia and thalamus in the generation of dystonia.

METHODS

Microelectrode recording was performed in the globus pallidus internus (GPi), ventral thalamic nuclear group ventral oral posterior/ventral intermediate, Vop/Vim) and subthalamic nucleus (STN) in patients with primary dystonia (n=11) or secondary dystonia (n=9) during surgery. Electromyogram (EMG) was simultaneously recorded in selected muscle groups. Single unit analysis and cross-correlations were carried out.

RESULTS

Three hundred and sixty-seven neurons were obtained from 29 trajectories (GPi: 13; Vop/Vim: 12; STN: 4), 87% exhibited altered neuronal activity including grouped discharges in GPi (n=79) and STN (n=37), long-lasting neuronal activity (n=70) and rapid neuronal discharge (n=86) in Vop/Vim. There were neurons in Vop, GPi and STN firing at the same frequency as EMG during dystonia (mean: 0.39 Hz, range 0.12-0.84 Hz). Significant correlations between neuronal activity and EMG at the frequency of dystonia were obtained (GPi: r2=0.7 (n=31), Vop/Vim: r2=0.64 (n=18) and STN: r2=0.86 (n=17)).

CONCLUSIONS

Consistent with previous findings of abnormalities observed in Vop/VIM and GPi in relation to dystonia, the present data further show that the altered activity in GPi, specifically in dorsal subregions of GPi, Vop/Vim and STN is likely to be directly involved in the production of dystonic movement. Dystonia-related neuronal activity observed in motor thalamus and basal ganglia nuclei of GPi and STN indicates a critical role of their interactions affecting both indirect and direct pathways in the development of either generalized or focal dystonia.

SIGNIFICANCE

These data support a central role of the basal ganglia in producing dystonic movements.

Mouvements anormaux de l’enfant : nouveautés thérapeutiques

Abnormal movements are not uncommon in childhood. Due to the severity of the abnormal movements or to the functional disability, a medical treatment is often required; the wide range of available pharmacological molecules and the absence of therapeutic consensus highlight the limited efficacy of the medical treatment on dystonic or athetoid movements, or severe tic disorders. The recent identification of the enzymatic defect implicated in metabolic diseases led to the development of specific treatment for newly recognized disorders, with more or less interesting results (creatine ou biotine supplementation). Recent progress in functional neurosurgery opened new fields in the treatment of movement disorders. Intrathecal baclofen was proved effective in the treatment of secondary dystonia, especially in patients with cerebral palsy. Deep brain stimulation is now an established therapy for patients with a generalized dystonic syndrome. Given the successful results of pallidal stimulation in dystonia, the indication of this procedure has been discussed in other types of abnormal movements.

Deep brain stimulation in the treatment of dyskinesia and dystonia

Deep brain stimulation (DBS) has become a mainstay of treatment for patients with movement disorders. This modality is directed at modulating pathological activity within basal ganglia output structures by stimulating some of their nuclei, such as the subthalamic nucleus (STN) and the globus pallidus internus (GPi), without making permanent lesions. With the accumulation of experience, indications for the use of DBS have become clearer and the effectiveness and limitations of this form of therapy in different clinical conditions have been better appreciated. In this review the authors discuss the efficacy of DBS in the treatment of dystonia and levodopa-induced dyskinesias. The use of DBS of the STN and GPi is very effective for the treatment of movement disorders induced by levodopa. The relative benefits of using the GPi as opposed to the STN as a target are still being investigated. Bilateral GPi stimulation is gaining importance in the therapeutic armamentarium for the treatment of dystonia. The DYT1 forms of generalized dystonia and cervical dystonias respond to DBS better than secondary dystonia does. Discrimination between the diverse forms of dystonia and a better understanding of the pathophysiological features of this condition will serve as a platform for improved outcomes.

Pallidal deep brain stimulation for longstanding severe generalized dystonia in Hallervorden-Spatz syndrome. Case report

Generalized dystonia is one of the most disabling movement disorders. Ablative stereotactic surgery such as pallidotomy has been performed for medically refractory dystonia. Recently, deep brain stimulation (DBS) has appeared as an alternative to ablative procedures. Nevertheless, there have been few published reports detailing improvement in dystonia with DBS. This 36-year-old man with Hallervorden-Spatz syndrome suffered from intractable primary generalized dystonia for 28 years. He was completely dependent for activities of daily living and wheelchair bound because of continuous severe dystonic movements in the face, tongue, neck, trunk, and upper and lower extremities while at rest. The Burke-Fahn-Marsden (BFM) Dystonia Rating Scale score was 112 (maximum 120 points). Bilateral DBS of the globus pallidus internus was performed and resulted in marked improvement in motor functioning and dystonic symptoms with a significant reduction in disability. The BFM score improved to 22.5 points (80% improvement) at 3 months postsurgery and the patient's dystonia was still well suppressed 1 year after surgery. Bilateral pallidal stimulation is an effective and safe treatment for intractable generalized dystonia in Hallervorden-Spatz syndrome, even if the disability is severe and longstanding.

Primary Dystonia Is More Responsive than Secondary Dystonia to Pallidal Interventions: Outcome after Pallidotomy or Pallidal Deep Brain Stimulation

OBJECTIVE

The response of patients with dystonia to pallidal procedures is not well understood. In this study, we assessed the postoperative outcome of patients with primary and secondary dystonia undergoing pallidotomy or pallidal deep brain stimulation.

METHODS

Fifteen patients with dystonia had pallidal surgery (lesions or deep brain stimulation). These included nine patients with primary dystonia (generalized and cervical dystonias) and six with secondary dystonia (generalized, segmental, and hemidystonias). There were nine male patients and six female patients. The mean age at onset was 21 years for primary dystonia and 18 years for secondary dystonia. The primary outcome measure was a Global Outcome Scale score for dystonia at 6 months after surgery. Other outcome measures were the Burke-Fahn-Marsden Dystonia Rating Scale and Toronto Western Spasmodic Torticollis Rating Scale scores.

RESULTS

The mean Global Outcome Scale score at 6 months for patients with primary dystonia was 3 (improvement in both movement disorder and function). In contrast, patients with secondary dystonia had a mean score of 0.83 (mild or no improvement in movement disorder with no functional improvement). All patients with primary dystonia had normal brains by magnetic resonance imaging, whereas five of six patients with secondary dystonia had basal ganglia abnormalities on their magnetic resonance imaging scans.

CONCLUSION

This study indicates that primary dystonia responds much better than secondary dystonia to pallidal procedures. We could not distinguish a difference in efficacy between pallidotomy and pallidal deep brain stimulation. The presence of basal ganglia abnormalities on the preoperative magnetic resonance imaging scan is an indicator of a lesser response to pallidal interventions for dystonia.

Rehabilitation of movement disorders11A commercial party with a direct financial interest in the results of the research supporting this article has conferred or will confer a financial benefit upon the author or one or more of the authors. Elovic is on the advisory board and speaker’s bureau of Allergan

This self-directed learning module highlights several movement disorders. These include dystonia, chorea, tremors, and myoclonus. A description of the clinical presentation and associated disease processes is presented. Although the discussion on treatment focuses on pharmacologic intervention, surgical options are presented when appropriate. Other movement disorders (ie, parkinsonism) are discussed elsewhere in the Study Guide.

OVERALL ARTICLE OBJECTIVES

(a) To define the various symptoms and etiologies of dystonia; (b) to define chorea and its treatment; (c) to define tremors, including associated neurologic disorders, plus pharmacologic and potential surgical interventions; and (d) to describe the symptoms, classification, and treatment of primary and secondary myoclonus.

Chronic stimulation of the globus pallidus internus for control of primary generalized dystonia

Our experience of deep brain stimulation of the globus pallidus internus (GPi-DBS) for dystonia is summarized. A total of 5 patients with primary generalized dystonia underwent GPi-DBS. There were 3 males and 2 females. The age at onset of dystonia ranged from 8 to 45 years and the age at surgery for GPi-DBS ranged from 17 to 59 years. Two of the patients had been treated previously by bilateral thalamotomy or unilateral pallidotomy at other clinics and then developed new symptoms or recurrence. All were stimulated bilaterally. No surgical complications were encountered. The symptoms of dystonia were scored by the Burke-Fahn-Marsden dystonia rating scale (BFMDRS). The scores ranged from 18 to 62 before surgery. An improvement in the symptoms of dystonia was observed soon after the initiation of GPi-DBS, and additional progressive improvement was noted during a period of months or even years after surgery. The score at 6 months after surgery reached a level ranging from 4 to 23. The improvement in score ranged from -51% to -92%. GPi-DBS produced a marked effect even in patients who had previously undergone thalamotomy or pallidotomy. At 6 months after surgery, all patients were receiving bipolar stimulation with a wide interpolar distance, using contact 0 or 1 as the cathode and contact 2 or 3 as the anode. Stimulation was being performed at an intensity of around 2.0 V with a pulse width of 0.21 ms at a high frequency ranging from 120 to 140 Hz. GPi-DBS represents an important therapeutic option in many patients with primary generalized dystonia.

Neurosurgical treatment of spasticity and other pediatric movement disorders

For children whose spasticity and movement disorders are inadequately treated by oral medications and botulinum toxins, neurosurgical procedures are now available to effectively treat spasticity, tremor, and many cases of dystonia. Spastic diplegia can be treated with selective lumbar rhizotomies, which significantly decrease spasticity, increase range of motion, and improve Gross Motor Function Measure scores. Children with spastic quadriparesis and those with secondary dystonia can be treated with intrathecal baclofen, which diminishes both spasticity and dystonia and is associated with improved function and quality of life. Children with primary dystonia and those with tremor can be treated with deep brain stimulation of the internal globus pallidus and thalamus, respectively. Some children with chorea respond to deep brain stimulation. There are no effective neurosurgical treatments for athetosis or ataxia. The effectiveness of neurosurgical treatments of pediatric movement disorders has increased significantly in the past 15 years.

Surgical therapy for dystonia

Surgical treatments for dystonia have been available since the early 20th century, but have improved in their efficacy to adversity ratio through a combination of technologic advances and better understanding of the role of the basal ganglia in dystonia. The word "dystonia" describes a phenotype of involuntary movement that may manifest from a variety of conditions. Dystonia may affect only certain regions of the body or may be generalized. It appears to be critical to determine whether the etiology underlying the dystonia is "primary" (ie, occurring from a genetic or idiopathic origin) or "secondary" (ie, occurring as a result of structural, metabolic, or neurodegenerative disorders). Secondary dystonias are far more common than primary dystonias. Primary dystonias respond well to pallidotomy or deep brain stimulation of the internal segment of the globus pallidum, whereas secondary dystonias appear to respond partially at best. Limited historic and current data suggest that the thalamus may be a promising target for the treatment of secondary dystonias, but more careful, prospective, randomized studies are needed. Combinations of bilateral targets are possible with the current technology of DBS, but not widely used due to surgical morbidity and expense. This article reviews the surgical treatment of dystonia from past to present, with a focus on separating the outcomes for primary versus secondary and generalized versus cervical dystonia.

Posteroventral pallidotomy in medically intractable postapoplectic monochorea: case report

BACKGROUND

Posteroventral pallidotomy is a widely accepted surgical procedure for treating medically intractable Parkinson's disease and Levo-dopa induced dyskinesia. In the surgical treatment of hyperkinetic movement disorders, generalized dystonia has recently become a favorable indication of posteroventral pallidotomy. However, a commonly recognized surgical procedure for treating choreiform movement disorders has not yet been established. Here we present an unusual experience of a posteroventral pallidotomy performed to treat a medically intractable monochorea caused by a vascular insult on the basal ganglia.

METHODS

A 63-year-old female presented with choreiform movement of the left upper limb that she had suffered for 5 months. She was found to have a hemorrhagic infarction in the right putaminal area. No other abnormal lesions were shown by magnetic resonance imaging except for a widening of the right cerebellopontine cistern because of an acoustic neurinoma removed 5 years previously. Despite medication with a dopamine antagonist, choreiform movement of the left limb had not improved, and the patient complained of rigidity and slowness of ambulation owing to the side effects of the medicine. A right posteroventral pallidotomy was performed with macrostimulation for a physiologic confirmation of the globus pallidus internus (GPi), which is the conventional target for Parkinson's disease. After coagulating the GPi target, the choreiform movement of the contralateral upper limb was completely abolished.

RESULTS

The postoperative course was uneventful and no recurrence of chorea was observed over a follow-up period of 6 months.

CONCLUSIONS

Stereotactic surgery for hyperkinetic movement disorders is not as common a procedure as that used for treating Parkinson's disease. Furthermore, there have been few reports of pallidal surgery for treating the chorea caused by an ischemic insult. However, on the basis of the current concept that varying types of hyperkinetic disorders may have a common pathophysiological mechanism, a posteroventral pallidotomy may be an alternative surgical procedure for treating medically intractable postapoplectic chorea like in an occasion of dystonia.

Stereotactic neurosurgery for movement disorders

Stereotactic neurosurgery for the treatment of movement disorders focuses primarily on the treatment of Parkinson's disease (PD), essential tremor (ET), and dystonia. The surgical targets in use are the subthalamic nucleus (STN) and the globus pallidus internus (GPi) for PD, GPi for dystonia, and ventralis intermedius (Vim) nucleus of the thalamus for ET. Following target selection, procedures include the generation of lesions or the placement of deep brain stimulating electrodes in the selected target. Additionally, transplantation has been used in the treatment of PD. The indications, outcomes, and risks of the various procedures are reviewed.

New perspectives on dystonia

Dystonia is a syndrome of sustained muscular contractions with numerous underlying etiologies. This review examines the varied phenomenology of dystonias, its evolving classification including recent genetic data as well as its clinical investigation and treatment. Although age of onset, anatomical distribution and family history are key elements of the investigation of dystonia, classification increasingly relies on etiologic and genetic criteria. Physiological abnormalities in striato-cortical circuits are common in dystonia but the pathophysiology is still unclear. In recent years, a great deal has been learned on the more common primary dystonias such as primary torsion dystonia and on dystonia-plus syndromes such as dopamine responsive dystonia. Treatment of dystonia has also evolved and there are now a number of therapeutic agents with clear beneficial effects including anticholinergics, benzodiazepines, and botulinum toxin and there is growing interest in neurofunctional surgery including deep brain stimulation.

Deep brain stimulation of the globus pallidus internus (GPI) for torsion dystonia--a report of two cases

Generalized dystonia is known as a type of movement disorder in which pharmacotherapeutic options are very limited. Deep Brain Stimulation (DBS) is well established for Parkinson's disease (PD) and tremor dominant movement disorders. We report on two cases of generalized dystonia which were successfully treated by chronic high frequency stimulation in the Globus pallidus internus (GPI). Two 26 and 27 years old males suffered from severe torsion dystonia and multisegmental dystonia of the lower limbs. Case 1 is a familiar type of dystonia (DYT1 positive). The onset of symptoms in both cases was at age 7. The complaints were initially treated with orally administered benzodiazepines, anticholinergic drugs, later by baclofen and L-DOPA. However there was no response. Case 2 was a patient with a history of left side dominated dystonia since the age of 8. It was first diagnosed as a psychogenic movement disorder. Prior to surgery he was treated with L-DOPA, anticholinergics, Baclofen without any effect. There was only a limited effect on high doses of diazepam. The patient is DYT1 negative. The target point was on both sides the GPI. Intraoperative computerized tomography (CT) and ventriculography (VG) were used for target setting. Furthermore microrecordings were helpful to ensure the exact electrode position. Surgery was performed under analgosedation. Two weeks after surgery we first observed a relief of symptoms in both cases. A significant reduction in the Burke-Fahn-Marsden-Dystonia Movement Rating Scale was observed at the 6 month follow-up (case 1: 95%, case 2: 80%). In case 1 a slight dystonic movement of the left ankle was the only remaining symptom under stimulation. The medication was continuously reduced. At the 24 month follow-up the effect of stimulation remained unchanged. However high stimulation parameters are required to maintain an optimal effect (mean 3.5 V, 400 microseconds, 145 Hz).

Results of deep brain stimulation for dystonia: a critical reappraisal

Deep brain stimulation for severe dystonia is still in the very first stage of development. Only single case reports or small case series have been reported to date. Best results have been obtained with pallidal stimulation in patients with primary generalised dystonia, especially in DYT1 mutation carriers. In secondary dystonia, conflicting results were reported. However, there is today enough promising evidence for a striking efficacy of pallidal stimulation in dystonia, supporting the need for further investigations in the field, with collaborative projects (regarding to the limited number of eligible patients); double-blind studies, including a consensus about surgical method; and a precise anatomic analysis of the position of the electrode. A careful assessment of the efficacy by using improved clinical scale is also warranted.

Deep brain stimulation for dystonia: patient selection and evaluation

Deep brain stimulation (DBS) for dystonia still needs to be considered investigational, because there are no controlled studies for this indication, the optimal target point is uncertain, and long-term effects are unknown. The striking improvement of levodopa-induced dyskinesias in Parkinson's disease by deep brain stimulation of the internal pallidum has encouraged the use of this therapy for generalized and severe segmental dystonia in children and adults. Single case and small cohort studies have reported impressive efficacy of pallidal DBS in patients with primary dystonia, especially DYT1 mutation carriers, but results in secondary dystonia are less conclusive. This article discusses the different factors influencing patient selection for surgical treatment and describes standardized methods and the caveats for clinical documentation of treatment results in dystonia.