A double-blind study on a patient with tardive dyskinesia treated with pallidal deep brain stimulation

Deep Brain Stimulation in the Treatment of Tardive Dyskinesia

Tardive dyskinesia (TD) is a phenomenon observed following the predominantly long-term use of dopamine receptor blockers (antipsychotics) widely used in psychiatry. TD is a group of involuntary, irregular hyperkinetic movements, mainly in the muscles of the face, eyelid, lips, tongue, and cheeks, and less frequently in the limbs, neck, pelvis, and trunk. In some patients, TD takes on an extremely severe form, massively disrupting functioning and, moreover, causing stigmatization and suffering. Deep brain stimulation (DBS), a method used, among others, in Parkinson's disease, is also an effective treatment for TD and often becomes a method of last resort, especially in severe, drug-resistant forms. The group of TD patients who have undergone DBS is still very limited. The procedure is relatively new in TD, so the available reliable clinical studies are few and consist mainly of case reports. Unilateral and bilateral stimulation of two sites has proven efficacy in TD treatment. Most authors describe stimulation of the globus pallidus internus (GPi); less frequent descriptions involve the subthalamic nucleus (STN). In the present paper, we provide up-to-date information on the stimulation of both mentioned brain areas. We also compare the efficacy of the two methods by comparing the two available studies that included the largest groups of patients. Although GPi stimulation is more frequently described in literature, our analysis indicates comparable results (reduction of involuntary movements) with STN DBS.

Pathophysiology, prognosis and treatment of tardive dyskinesia

Tardive dyskinesia (TD), a movement disorder associated with antipsychotics, most frequently affects the lower face and jaw muscles, but can also affect walking, breathing and use of the hands and limbs. Knowledge of TD among physicians may be limited, and the pathophysiology of TD is poorly understood. We conducted this review to summarise the current knowledge surrounding the pathophysiology of TD and present recommendations for prevention and treatment based on a literature search and roundtable discussion attended by psychiatrists in Japan. It has been suggested that dopamine hypersensitivity, damaged gamma-aminobutyric acidergic neurons and/or increased production of reactive oxygen species may contribute to development of TD. Symptoms can profoundly affect everyday life; patients who develop TD have poorer prognoses, worse health-related quality of life, greater social withdrawal and higher mortality than patients without TD. Traditional treatment options include dietary supplements, although evidence for their effectiveness is low. Among pharmaceutical interventions, there is moderate evidence that switching to the second-generation antipsychotic clozapine, which has a lower affinity for dopamine D₂ receptors than other antipsychotics, may improve symptoms. Vesicular monoamine transporter 2 (VMAT-2) inhibitors, which oppose the increased dopaminergic activity associated with prolonged antipsychotic use by interfering with dopamine uptake and storage, have the strongest evidence for efficacy. VMAT-2 inhibitors are approved in the United States for the treatment of TD, and the first VMAT-2 inhibitor was approved in Japan for this indication in March 2022. Most guidelines recommend treating TD by first reducing the dose of antipsychotics or switching to clozapine or other second-generation antipsychotics, which have a lower association with TD than first-generation antipsychotics. We recommend focusing on prevention and monitoring for TD when prescribing antipsychotics, given that TD is often irreversible. Physicians should treat with antipsychotics only when necessary and at the lowest effective dose, and frequently monitor for TD symptoms.

PLAIN LANGUAGE SUMMARY

Plain Language Summary (In Japanese).

VISUAL SUMMARY

Visual Summary (In Japanese).

Deep Brain Stimulation of the Globus Pallidus Internus for Secondary Dystonia: Clinical Cases and Systematic Review of the Literature Regarding the Effectiveness of Globus Pallidus Internus versus Subthalamic Nucleus

OBJECTIVE

Deep brain stimulation (DBS) is a frequently applied therapy in primary dystonia. For secondary dystonia, the effects can be less favorable. We share our long-term findings in 9 patients with severe secondary dystonia and discuss these findings in the light of the literature.

METHODS

Patients who had undergone globus pallidus internus (GPi)-DBS for secondary dystonia were included. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores, clinical improvement rates, follow-up periods, stimulation parameters and the need for internal pulse generator replacements were analyzed. The PubMed and Google Scholar databases were searched for articles describing GPi-DBS and subthalamic nucleus (STN)-DBS only for secondary dystonia cases. Keywords were "dystonia," "deep brain stimulation," "GPi," "dystonia," "deep brain stimulation," and "STN."

RESULTS

A total of 9 secondary dystonia patients (5 male, 4 female) had undergone GPi-DBS with microelectrode recording in our units. The mean follow-up period was 29 months. The average BFMDRS score was 58.2 before the surgery, whereas the mean value was 36.5 at the last follow-up of the patients (mean improvement, 39%; minimum, 9%; maximum, 63%). In the literature review, we identified 264 GPi-DBS cases (mean follow-up, 19 months) in 72 different articles about secondary dystonia. The mean BFMDRS improvement rate was 52%. In 146 secondary dystonia cases, reported in 19 articles, STN-DBS was performed. The average follow-up period was 20 months and the improvement in BFMDRS score was 66%.

CONCLUSIONS

Although GPi-DBS has favorable long-term efficacy and safety in the treatment of patients with secondary dystonia, STN seems a promising target for stimulation in patients with secondary dystonia. Further studies including a large number of patients, longer follow-up periods, and more homogenous patients are necessary to establish the optimal target for DBS in the management of secondary dystonias.

Valbenazine for the Treatment of Adults with Tardive Dyskinesia

PURPOSE OF REVIEW

This a comprehensive review of the literature regarding the use of Valbenazine in treating tardive dyskinesia. A primarily oral movement disorder induced by chronic exposure to certain classes of medications, tardive dyskinesia is often resistant to many therapeutic approaches. This review presents the background, evidence, and indications for the use of Valbenazine as a treatment option for this condition.

RECENT FINDINGS

Tardive dyskinesia is a disorder arising from long-term exposure to medications that blocked dopamine receptors, primarily antipsychotics. It is characterized by abnormal movements of the oral-buccal-lingual structures as well as associated pain and hypertrophy. Simply stopping the use of the dopamine blocking agents effectively alleviates the symptoms but is not always reliable hence the need for another therapeutic approach.Valbenazine is thought to function as a highly selective inhibitor of the VMAT2 vesicular monoamine transporter resulting in decreased availability of dopamine in the presynaptic cleft. This leads to decreased dopaminergic activation of the striatal motor pathway. The FDA approved Valbenazine in 2017 to treat tardive dyskinesia in adults and needs to be evaluated with existing therapeutic approaches.

SUMMARY

The chronic use of dopamine receptor blocking agents, most commonly antipsychotics, can lead to a movement disorder called tardive dyskinesia. Once symptom onset has occurred, these movement abnormalities can persist for years to permanently, depending on the speed and effectiveness of treatment. Valbenazine is a relatively newer option for the treatment of tardive dyskinesia in adults. Compared to other pharmaceutical agents, it is more selective and has limited toxicities making it an effective treatment regimen. However, further research, including additional direct comparison studies, should be conducted to fully evaluate this drug's usefulness.

Long-Term Follow-Up of 12 Patients Treated with Bilateral Pallidal Stimulation for Tardive Dystonia

Tardive dystonia (TD) is a side effect of prolonged dopamine receptor antagonist intake. TD can be a chronic disabling movement disorder despite medical treatment. We previously demonstrated successful outcomes in six patients with TD using deep brain stimulation (DBS); however, more patients are needed to better understand the efficacy of DBS for treating TD. We assessed the outcomes of 12 patients with TD who underwent globus pallidus internus (GPi) DBS by extending the follow-up period of previously reported patients and enrolling six additional patients. All patients were refractory to pharmacotherapy and were referred for surgical intervention by movement disorder neurologists. In all patients, DBS electrodes were implanted bilaterally within the GPi under general anesthesia. The mean ages at TD onset and surgery were 39.2 ± 12.3 years and 44.6 ± 12.3 years, respectively. The Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS) performed the preoperative and postoperative evaluations. The average BFMDRS improvement rate at 1 month postoperatively was 75.6 ± 27.6% (p < 0.001). Ten patients were assessed in the long term (78.0 ± 50.4 months after surgery), and the long-term BFMDRS improvement was 78.0 ± 20.4%. Two patients responded poorly to DBS. Both had a longer duration from TD onset to surgery and older age at surgery. A cognitive and psychiatric decline was observed in the oldest patients, while no such decline ware observed in the younger patients. In most patients with TD, GPi-DBS could be a beneficial therapeutic option for long-term relief of TD.

Tardive Dyskinesia: Spotlight on Current Approaches to Treatment

Tardive dyskinesia (TD) is a debilitating, iatrogenic, and potentially severe movement disorder characterized by involuntary, repetitive, purposeless movements that are present throughout the body. The authors present a review of studies of past, current, and possible future treatment approaches to the management of TD; consider the phenomenology, assessment, and putative pathophysiological mechanisms of TD, early pharmacological trials, a focus on the newer vesicular monoamine transporter 2 inhibitors, and other evidence-based approaches, such as clozapine; and present preliminary evidence for newer approaches, such as deep brain stimulation and repetitive transcranial magnetic stimulation. On the basis of the evidence presented here, the authors highlight the importance of early recognition and assessment of TD, as well as how to best approach management of these often incapacitating symptoms.

Resolution of tardive tremor after bilateral subthalamic nucleus deep brain stimulation placement

Background:

Tardive tremor (TT) is an underrecognized manifestation of tardive syndrome (TS). In our experience, TT is a rather common manifestation of TS, especially in a setting of treatment with aripiprazole, and is a frequent cause of referrals for the evaluation of idiopathic Parkinson disease. There are reports of successful treatment of tardive orofacial dyskinesia and dystonia with deep brain stimulation (DBS) using globus pallidus interna (GPi) as the primary target, but the literature on subthalamic nucleus (STN) DBS for tardive dyskinesia (TD) is lacking. To the best of our knowledge, there are no reports on DBS treatment of TT.

Case Description:

A 75-year-old right-handed female with the medical history of generalized anxiety disorder and major depressive disorder had been treated with thioridazine and citalopram from 1980 till 2010. Around 2008, she developed orolingual dyskinesia. She was started on tetrabenazine in June 2011. She continued to have tremors and developed Parkinsonian gait, both of which worsened overtime. She underwent DBS placement in the left STN in January 2017 with near-complete resolution of her tremors. She underwent right STN implantation in September 2017 with similar improvement in symptoms.

Conclusion:

While DBS-GPi is the preferred treatment in treating oral TD and dystonia, DBS-STN could be considered a safe and effective target in patients with predominating TT and/or tardive Parkinsonism. This patient saw a marked improvement in her symptoms after implantation of DBS electrodes, without significant relapse or recurrence in the years following implantation.

Management of Tardive Syndrome: Medications and Surgical Treatments

Tardive syndrome (TS) is an iatrogenic, often persistent movement disorder caused by drugs that block dopamine receptors. It has a broad phenotype including movement (orobuccolingual stereotypy, dystonia, tics, and others) and nonmotor features (akathisia and pain). TS has garnered increased attention of late because of the Food and Drug Administration approval of the first therapeutic agents developed specifically for this purpose. This paper will begin with a discussion on pathogenesis, clinical features, and epidemiology. However, the main focus will be treatment options currently available for TS including a suggested algorithm based on current evidence. Recently, there have been significant advances in TS therapy, particularly with the development of 2 new vesicular monoamine transporter type 2 inhibitors for TS and with new data on the efficacy of deep brain stimulation. The discussion will start with switching antipsychotics and the use of clozapine monotherapy which, despite the lack of higher-level evidence, should be considered for the treatment of psychosis and TS. Anti-dyskinetic drugs are separated into 3 tiers: 1) vesicular monoamine transporter type 2 inhibitors, which have level A evidence, are approved for use in TS and are recommended first-choice agents; 2) drugs with lower level of evidence for efficacy including clonazepam, Ginkgo biloba, and amantadine; and 3) drugs that have the potential to be beneficial, but currently have insufficient evidence including levetiracetam, piracetam, vitamin B6, melatonin, baclofen, propranolol, zolpidem, and zonisamide. Finally, the roles of botulinum toxin and surgical therapy will be examined. Current therapies, though improved, are symptomatic. Next steps should focus on the prevention and reversal of the pathogenic process.

Deep brain stimulation for dystonia

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Current treatment of tardive dyskinesia

Tardive dyskinesia (TD) is a common, iatrogenic movement disorder affecting many individuals treated with dopamine-receptor blocking agents (DRBAs). Studying treatment of TD can be complex, as the symptoms can be affected by changes in either dosage or type of DRBA, as well as by the variable natural course of the disease. Historically many pharmacological therapies have been studied in TD, finding varying degrees of treatment success. Most recently, the VMAT2 inhibitors valbenazine and deutetrabenazine were rigorously studied in TD in large, phase III clinical trials, and were shown to be beneficial in this population. In this article, we will review various treatments of TD, including manipulation of the offending agent, VMAT2 inhibitors, other non-VMAT2-inhibiting medications, and non-pharmacological approaches.

Tardive Dyskinesia Associated with Atypical Antipsychotics: Prevalence, Mechanisms and Management Strategies

All antipsychotics, including the atypical antipsychotics (AAPs), may cause tardive dyskinesia (TD), a potentially irreversible movement disorder, the pathophysiology of which is currently unknown. The prevention and treatment of TD remain major challenges for clinicians. We conducted a PubMed search to review the prevalence and etiology of and management strategies for TD associated with AAPs. TD prevalence rates varied substantially between studies, with an estimated prevalence of around 20% in patients using AAPs. The risk of TD is lower with AAPs than with typical antipsychotics (TAPs) but remains a problem because AAPs are increasingly being prescribed. Important risk factors associated with TD include the duration of antipsychotic use, age, and ethnicity other than Caucasian. Theories about the etiology of TD include supersensitivity of the dopamine receptors and oxidative stress, but other neurotransmitters and factors are probably involved. Studies concerning the management of TD have considerable methodological limitations. Thus, recommendations for the management of TD are based on a few trials and clinical experience, and no general guidelines for the management of TD can be established. The best management strategy remains prevention. Caution is required when prescribing antipsychotics, and regular screening is needed for early detection of TD. Other strategies may include reducing the AAP dosage, switching to clozapine, or administering vesicular monoamine transporter (VMAT)-2 inhibitors. In severe cases, local injections of botulinum toxin or deep brain stimulation may be considered. More clinical trials in larger samples are needed to gather valid information on the effect of interventions targeting TD.

Antipsychotic-induced Tardive dyskinesia: from biological basis to clinical management

INTRODUCTION

Tardive dyskinesia (TD) is a chronic and disabling movement disorder with a complex pathophysiological basis. A significant percentage of patients does not receive correct diagnosis, resulting in delayed or inaccurate treatment and poor outcome. Therefore, there is a critical need for prompt recognition, implementation of efficacious treatment regimens and long-term follow up of patients with TD. Areas covered: The current paper provides an overview of emerging data concerning proposed pathophysiology theories, epidemiology, risk factors, and therapeutic strategies for TD. Expert commentary: Despite considerable research efforts, TD remains a challenge in the treatment of psychosis as the available strategies remain sub-optimal. The best scenario will always be the prophylaxis or prevention of TD, which entails limiting the use of antipsychotics.

Pharmacotherapy for the treatment of tardive dyskinesia in schizophrenia patients

INTRODUCTION

Tardive dyskinesia (TD) is an iatrogenic movement disorder most commonly observed in patients with psychotic disorders who are treated with dopamine blocking antipsychotic medications. Treatment options are limited, and recommendations for treatment are based on a relative scarcity of evidence. Areas covered: After briefly highlighting current mechanistic theories of TD, this review will discuss the evidence for a number of medications of several different classes that have been studied for the treatment of TD since the 1970s with an emphasis on placebo controlled trials when possible. We used a Pubmed search of primary studies, reviews, and metaanalyses on the topic of TD treatment in order to cover this topic. Expert opinion: Treatment of TD is difficult given limited data and incomplete understanding of the mechanism. Treatment of TD must be evaluated on an individual basis with careful weight given to severity of symptoms. We suggest the use of atypical versus conventional antipsychotics whenever possible and would recommend trials with one or more of a number of additional agents starting with valbenazine.

Drug-Induced Dyskinesia, Part 2: Treatment of Tardive Dyskinesia

Dyskinesias encompass a variety of different hyperkinetic phenomenologies, particularly chorea, dystonia, stereotypies, and akathisia. The main types of drug-induced dyskinesias include levodopa-induced dyskinesia (LID) in patients with Parkinson's disease and tardive syndrome (TS), typically present in patients with psychiatric or gastrointenstinal disorders treated with dopamine receptor blocking drugs, also referred to as neuroleptics. Besides preventive measures (i.e., avoiding the use of the offending drugs), general treatment strategies include slow taper of the offending agent and use of dopamine-depleting agents like tetrabenazine. Botulinum toxin may be helpful for wearing off focal dystonia and some forms of tardive dystonia. Deep brain stimulation is usually reserved for patients with disabling motor fluctuations, LID, and for severe TS that cannot be managed medically.

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

Background

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Therapeutic Perspective on Tardive Syndrome with Special Reference to Deep Brain Stimulation

Tardive syndrome (TDS) is a potentially permanent and irreversible hyperkinetic movement disorder caused by exposure to dopamine receptor blocking agents. Guidelines published by the American Academy of Neurology recommend pharmacological first-line treatment for TDS with clonazepam (level B), ginkgo biloba (level B), amantadine (level C), and tetrabenazine (level C). Recently, a class II study provided level C evidence for use of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in patients with TDS. Although the precise pathogenesis of TDS remains to be elucidated, the beneficial effects of GPi-DBS in patients with TDS suggest that the disease may be a basal ganglia disorder. In addition to recent advances in understanding the pathophysiology of TDS, this article introduces the current use of DBS in the treatment of medically intractable TDS.

Uncommon applications of deep brain stimulation in hyperkinetic movement disorders

Background

In addition to the established indications of tremor and dystonia, deep brain stimulation (DBS) has been utilized less commonly for several hyperkinetic movement disorders, including medication-refractory myoclonus, ballism, chorea, and Gilles de la Tourette (GTS) and tardive syndromes. Given the lack of adequate controlled trials, it is difficult to translate published reports into clinical use. We summarize the literature, draw conclusions regarding efficacy when possible, and highlight concerns and areas for future study.

Methods

A Pubmed search was performed for English-language articles between January 1980 and June 2014. Studies were selected if they focused primarily on DBS to treat the conditions of focus.

Results

We identified 49 cases of DBS for myoclonus-dystonia, 21 for Huntington's disease, 15 for choreacanthocytosis, 129 for GTS, and 73 for tardive syndromes. Bilateral globus pallidus interna (GPi) DBS was the most frequently utilized procedure for all conditions except GTS, in which medial thalamic DBS was more common. While the majority of cases demonstrate some improvement, there are also reports of no improvement or even worsening of symptoms in each condition. The few studies including functional or quality of life outcomes suggest benefit. A limited number of studies included blinded on/off testing. There have been two double-blind controlled trials performed in GTS and a single prospective double-blind, uncontrolled trial in tardive syndromes. Patient characteristics, surgical target, stimulation parameters, and duration of follow-up varied among studies.

Discussion

Despite these extensive limitations, the literature overall supports the efficacy of DBS in these conditions, in particular GTS and tardive syndromes. For other conditions, the preliminary evidence from small studies is promising and encourages further study.

Tardive dyskinesia in patients treated with atypical antipsychotics: case series and brief review of etiologic and treatment considerations

Tardive dyskinesia (TD) is a disfiguring side-effect of antipsychotic medications that is potentially irreversible in affected patients. Newer atypical antipsychotics are felt by many to have a lower risk of TD. As a result, many clinicians may have developed a false sense of security when prescribing these medications. We report five cases of patients taking atypical antipsychotics who developed TD, review the risk of TD, its potential etiologic mechanisms, and treatment options available. The goal of this paper is to alert the reader to continue to be diligent in obtaining informed consent and monitoring for the onset of TD in patients taking atypical antipsychotics.

Tardive dyskinesia: therapeutic options for an increasingly common disorder

Tardive dyskinesia (TD) is a serious, often disabling, movement disorder that is caused by medications that block dopamine receptors (i.e., neuroleptics, anti-emetics). There is currently no standard treatment approach for physicians confronted with such patients. This may be the result of notions that TD is disappearing because of the switch to second-generation antipsychotic agents and that it is largely reversible. In this article we demonstrate that second-generation antipsychotics do, indeed, cause TD and, in fact, the frequency is likely higher than expected because of growing off-label uses and a tripling of prescriptions written in the last 10 years. In addition, studies demonstrate that TD actually remits in only a minority of patients when these drugs are withdrawn. Furthermore, neuroleptic agents are often utilized to treat TD, despite prolonged exposure being a risk factor for irreversibility. The outcome of these trends is a growing population afflicted with TD. We review non-neuroleptic agents that have shown positive results in small, early-phase, blinded trials, including tetrabenazine, amantadine, levetiracetam, piracetam, clonazepam, propranolol, vitamin B6, and Ginkgo biloba. Other options, such as botulinum toxin and deep brain stimulation, will also be discussed, and a suggested treatment algorithm is provided. While these agents are reasonable treatment options at this time there is a need, with a concerted effort between neurology and psychiatry, for full-scale drug development, including multicenter, randomized, blinded trials to confirm the effectiveness of the agents that were positive in phase 2 trials and the development of newer ones.

Deep brain stimulation for dystonia

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

Deep brain stimulation for dystonia

The few reported controlled studies show that bilateral stimulation of the globus pallidus interna (GPi) is a safe and effective long-term treatment for hyperkinetic disorders. However, the recently published data on deep brain stimulation (DBS) applied to different targets or patients (especially those with secondary dystonia) are mainly uncontrolled case reports, precluding a clear determination of its efficacy, and providing little guidance as to the choice of a "good" target in a "good" patient. This chapter reviews the literature on DBS in primary dystonia, paying particular attention to the risk:benefit ratio in focal and segmental dystonias (cervical dystonia, cranial dystonia) and to the predictive factors for a good outcome. The chapter also highlights recent data on the marked benefits of the technique in myoclonus dystonia (in which pallidal, as opposed to thalamic, stimulation is more effective) and in tardive dystonia-dyskinesia. Although, the decision to treat appears relatively straightforward in patients with primary dystonia, myoclonus-dystonia, and tardive dystonia who have a normal findings on magnetic resonance imaging and normal cognitive function, there are still no reliable tools to help predict the timescale of postoperative benefit. This chapter provides a comprehensive analysis of the use of the treatment in various types of secondary dystonia, with little to moderate benefit in most cases, based on single cases or small series. Beyond the reduction in the severity of dystonia, the global motor and functional outcome is difficult to determine owing to the paucity of adequate evaluation tools. Because of the large interpatient variability, different targets may be effective depending on the symptoms in each individual.

Treatment of neurolept-induced tardive dyskinesia

Tardive dyskinesia (TDK) includes orobuccolingual movements and "piano-playing" movements of the limbs. It is a movement disorder of delayed onset that can occur in the setting of neuroleptic treatment as well as in other diseases and following treatment with other drugs. The specific pathophysiology resulting in TDK is still not completely understood but possible mechanisms include postsynaptic dopamine receptor hypersensitivity, abnormalities of striatal gamma-aminobutyric acid (GABA) neurons, and degeneration of striatal cholinergic interneurons. More recently, the theory of synaptic plasticity has been proposed. Considering these proposed mechanisms of disease, therapeutic interventions have attempted to manipulate dopamine, GABA, acetylcholine, norepinephrine and serotonin pathways and receptors. The data for the effectiveness of each class of drugs and the side effects were considered in turn.

Globus pallidus interna deep brain stimulation for tardive dyskinesia: case report and review of the literature

Tardive dyskinesia (TD) can be a disabling condition and is frequently refractory to medical therapy. Over the past decade there have been many reports of TD patients experiencing significant benefit with deep brain stimulation (DBS) of the globus pallidus interna (GPi). The growing literature on this treatment option for TD consists predominantly of case reports and series. The reported benefit ranges widely, but the majority of cases experienced at least a 50% improvement in symptoms. The anatomical distribution of dyskinesias has not clearly influenced outcome, though fixed postures appear less likely to improve than phasic movements. Onset of benefit can be immediate or take months, and benefit is sustained in most cases, for at least 6 months and up to several years. A wide variety of voltages, frequencies, and pulse widths have demonstrated efficacy. A small number of reports which examined psychiatric symptoms before and after surgery did not find any decline, and in some cases revealed improvement in mood. However, these overall positive results should be interpreted with caution, as the majority of reports lacked blinded assessments, control groups, or standardized therapy parameters. Finally, we present an illustrative case of refractory tardive dyskinesia treated with GPi-DBS with 5 years of follow-up and 4 accompanying video segments.

Long-stay psychiatric patients: a prospective study revealing persistent antipsychotic-induced movement disorder

OBJECTIVE

The purpose of this study was to assess the frequency of persistent drug-induced movement disorders namely, tardive dyskinesia (TD), parkinsonism, akathisia and tardive dystonia in a representative sample of long-stay patients with chronic severe mental illness.

METHOD

Naturalistic study of 209, mainly white, antipsychotic-treated patients, mostly diagnosed with psychotic disorder. Of this group, the same rater examined 194 patients at least two times over a 4-year period, with a mean follow-up time of 1.1 years, with validated scales for TD, parkinsonism, akathisia, and tardive dystonia.

RESULTS

The frequencies of persistent movement disorders in the sample were 28.4% for TD, 56.2% for parkinsonism, 4.6% for akathisia and 5.7% for tardive dystonia. Two-thirds of the participants displayed at least one type of persistent movement disorder.

CONCLUSIONS

Persistent movement disorder continues to be the norm for long-stay patients with chronic mental illness and long-term antipsychotic treatment. Measures are required to remedy this situation.

Deep brain stimulation of the subthalamic or entopeduncular nucleus attenuates vacuous chewing movements in a rodent model of tardive dyskinesia

Deep brain stimulation (DBS) has recently emerged as a potential intervention for treatment-resistant tardive dyskinesia (TD). Despite promising case reports, no consensus exists as yet regarding optimal stimulation parameters or neuroanatomical target for DBS in TD. Here we report the use of DBS in an animal model of TD. We applied DBS (100 μA) acutely to the entopeduncular nucleus (EPN) or subthalamic nucleus (STN) in rats with well established vacuous chewing movements (VCMs) induced by 12 weeks of haloperidol (HAL) treatment. Stimulation of the STN or EPN resulted in significant reductions in VCM counts at frequencies of 30, 60 or 130 Hz. In the STN DBS groups, effects were significantly more pronounced at 130 Hz than at lower frequencies, whereas at the EPN the three frequencies were equipotent. Unilateral stimulation at 130 Hz was also effective when applied to either nucleus. These results suggest that stimulation of either the EPN or STN significantly alleviates oral dyskinesias induced by chronic HAL. The chronic HAL VCM model preparation may be useful to explore mechanisms underlying DBS effects in drug-induced dyskinesias.

Nonprimary dystonias

Dystonias can be classified as primary or secondary, as dystonia-plus syndromes, and as heredodegenerative dystonias. Their prevalence is difficult to determine. In our experience 80-90% of all dystonias are primary. About 20-30% of those have a genetic background; 10-20% are secondary, with tardive dystonia and dystonia in cerebral palsy being the most common forms. If dystonia in spastic conditions is accepted as secondary dystonia, this is the most common form of all dystonia. In primary dystonias, the dystonic movements are the only symptoms. In secondary dystonias, dystonic movements result from exogenous processes directly or indirectly affecting brain parenchyma. They may be caused by focal and diffuse brain damage, drugs, chemical agents, physical interactions with the central nervous system, and indirect central nervous system effects. Dystonia-plus syndromes describe brain parenchyma processes producing predominantly dystonia together with other movement disorders. They include dopa-responsive dystonia and myoclonus-dystonia. Heredodegenerative dystonias are dystonic movements occurring in the context of other heredodegenerative disorders. They may be caused by impaired energy metabolism, impaired systemic metabolism, storage of noxious substances, oligonucleotid repeats and other processes. Pseudodystonias mimic dystonia and include psychogenic dystonia and various orthopedic, ophthalmologic, vestibular, and traumatic conditions. Unusual manifestations, unusual age of onset, suspect family history, suspect medical history, and additional signs may indicate nonprimary dystonia. If they are suspected, etiological clarification becomes necessary. Unfortunately, potential etiologies are legion. Diagnostic algorithms can be helpful. Treatment of nonprimary dystonias, with few exceptions, does not differ from treatment of primary dystonias. The most effective treatment for focal and segmental dystonias is local botulinum toxin injections. Deep brain stimulation of the globus pallidus internus is effective for generalized dystonia. Antidystonic drugs, including anticholinergics, tetrabenazine, clozapine, and gamma-aminobutyric acid receptor agonists, are less effective and often produce adverse effects. Dopamine is extremely effective in dopa-responsive dystonia. The Bertrand procedure can be effective in cervical dystonia. Other peripheral surgery, including myotomy, myectomy, neurotomy, rhizotomy, ramizectomy, and accessory nerve neurolysis, has largely been abandoned. Central surgery other than deep brain stimulation is obsolete. Adjuvant therapies, including orthoses, physiotherapy, ergotherapy, behavioral therapy, social support, and support groups, may be helpful. Analgesics should also be considered where appropriate.

Deep brain stimulation: technology at the cutting edge

Deep brain stimulation (DBS) surgery has been performed in over 75,000 people worldwide, and has been shown to be an effective treatment for Parkinson's disease, tremor, dystonia, epilepsy, depression, Tourette's syndrome, and obsessive compulsive disorder. We review current and emerging evidence for the role of DBS in the management of a range of neurological and psychiatric conditions, and discuss the technical and practical aspects of performing DBS surgery. In the future, evolution of DBS technology may depend on several key areas, including better scientific understanding of its underlying mechanism of action, advances in high-spatial resolution imaging and development of novel electrophysiological and neurotransmitter microsensor systems. Such developments could form the basis of an intelligent closed-loop DBS system with feedback-guided neuromodulation to optimize both electrode placement and therapeutic efficacy.

Tardive dyskinesia and withdrawal emergent syndrome in children

Tardive dyskinesia (TD) is a well-recognized and sometimes permanent adverse effect of treatment with dopamine receptor-blocking drugs (DRBDs), also referred to as neuroleptics. This iatrogenic disorder has been well characterized in adults, but not extensively studied in children. Withdrawal emergent syndrome (WES) is another pediatric movement disorder related to the use of DRBDs. TD and WES are among the most feared adverse effects of DRBD treatment, and have important medical and legal implications. We review published studies of children under the age of 18 years who were exposed to DRBD to determine the clinical spectrum and estimate the possible prevalence of TD and WES. We particularly wish to draw attention to the phenomenology, clinical course and treatment of these childhood-onset disorders. Although avoiding DRBDs is the best strategy for minimizing the risk of TD and WES, physicians who evaluate children exposed to DRBDs must be vigilant and recognize the early symptoms and signs of these syndromes to provide appropriate clinical management.