Are Second-Generation Antipsychotics Useful in Tardive Dystonia?

Genetic association study detected misalignment in previous whole exome sequence: association study of ZNF806 and SART3 in tardive dystonia

Tardive dystonia is one of the most serious types of extrapyramidal symptoms that antipsychotics can cause. There is no established treatment to relieve this symptom, and its etiology is unclear. Recently, we identified very rare single-nucleotide polymorphisms (SNPs) on ZNF806 and SART3 by exome sequencing in three patients with profoundly severe tardive dystonia. Here, we conducted an association study (case, N = 16 vs. control, N = 96) on the rarest SNP selected from each gene. The results showed that rs2287546 on SART3 was not related to tardive dystonia and that rs4953961 on ZNF806 was a heterozygote in all the subjects, implying the absence of a rare SNP in this locus. We found three other genomic regions with high similarity to the relevant region on ZNF806 by BLAT searches. This strongly suggested a misalignment error in this region in our previous exome sequence. In conclusion, ZNF806 and SART3 are unlikely to be related to tardive dystonia.

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

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

Long-Term Response to Clozapine and Its Clinical Correlates in the Treatment of Tardive Movement Syndromes: A Naturalistic Observational Study in Patients With Psychotic Disorders

PURPOSE

Given that switching to clozapine is an important treatment option for tardive movement syndrome (TMS), its effect and clinical correlates have not been fully explored yet. This study investigated the improvement of TMS after switching to clozapine and factors associated with the response in a naturalistic outpatient setting.

METHODS

Subjects were 35 patients with schizophrenia or bipolar disorder receiving only clozapine as an antipsychotic drug for more than 12 months. Their prior antipsychotics were switched to clozapine after the onset of tardive dyskinesia and/or tardive dystonia. Tardive movement syndrome and clinical characteristics were assessed through direct examination and review of hospital records.

FINDINGS

Offending antipsychotics administered at the time of TMS onset were second-generation antipsychotics in 88.6% of patients. Tardive movement syndrome symptoms were remitted in 65.7% of patients after switching to clozapine. Younger age, younger age at onset of TMS, and lower baseline Abnormal Involuntary Movement Scale score were significantly associated with remission of TMS. Female sex and good antipsychotic effects of clozapine showed a trend of association with better response.

IMPLICATIONS

Clozapine seems to be an excellent treatment option for TMS in the era of second-generation antipsychotics, especially for younger patients with mild tardive dyskinesia. Clinical trials comparing the effect of switching antipsychotics to clozapine with add-on therapy of new drugs targeting TMS are difficult to design in ordinary clinical settings. Therefore, more naturalistic observational studies are warranted to identify predictors of TMS response to clozapine.

The psychopharmacology of catatonia, neuroleptic malignant syndrome, akathisia, tardive dyskinesia, and dystonia

Although highly prevalent, motor syndromes in psychiatry and motor side effects of psychopharmacologic agents remain understudied. Catatonia is a syndrome with specific motor abnormalities that can be seen in the context of a variety of psychiatric and somatic conditions. The neuroleptic malignant syndrome is a lethal variant, induced by antipsychotic drugs. Therefore, antipsychotics should be used with caution in the presence of catatonic signs. Antipsychotics and other dopamine-antagonist drugs can also cause motor side effects such as akathisia, (tardive) dyskinesia, and dystonia. These syndromes share a debilitating impact on the functioning and well-being of patients. To reduce the risk of inducing these side effects, a balanced and well-advised prescription of antipsychotics is of utmost importance. Clinicians should be able to recognize motor side effects and be knowledgeable of the different treatment modalities.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Medical treatment of dystonia

Therapeutic strategies in dystonia have evolved considerably in the past few decades. Three major treatment modalities include oral medications, botulinum toxin injections and surgical therapies, particularly deep brain stimulation. Although there has been a tremendous interest in the later two modalities, there are relatively few recent reviews of oral treatment. We review the medical treatment of dystonia, focusing on three major neurotransmitter systems: cholinergic, GABAergic and dopaminergic. We also provide a practical guide to medication selection, therapeutic strategy and unmet needs.

The Symptomatic Treatment of Acquired Dystonia: A Systematic Review

Background

Acquired dystonia is caused by an acquired or exogenous event. Although the therapeutic armamentarium used in clinical practice is more or less similar to that used for inherited or idiopathic dystonia, formal proof of the efficacy of these interventions in acquired dystonia is lacking.

Methods

The authors attempt to provide a comprehensive and systematic review of the current evidence for medical and allied health care treatment strategies in acquired dystonias. The PubMed, Cochrane Library, MEDLINE, Web of Science, PiCarta, and PsycINFO databases were searched up to December 2015, including randomized controlled trials, patient-control studies, and case series or single case reports containing a report on clinical outcome.

Results

There are level 3 practice recommendations for botulinum toxin injections and globus pallidus pars interna deep brain stimulation for tardive dystonia and dystonic cerebral palsy as well as intrathecal baclofen for dystonic cerebral palsy. There are insufficient and conflicting data on the effect (vs. the hazard) of other pharmacological interventions, and limited work has been done on other forms of neurostimulation and allied health care. Because no class A1 or A2 studies were identified, level 1 or 2 practice recommendations could not be deducted for a specific treatment intervention.

Conclusions

To improve the current medical and allied health care treatment options for patients with acquired dystonia, high-quality trials that examine the efficacy of therapies need to be performed.