Deep brain stimulation for intractable tardive dystonia: Literature overview

Pallidal deep brain stimulation for tardive dystonia: meta-analysis of clinical outcomes

INTRODUCTION

Tardive dystonia (TD) is a disabling complication of pharmacological therapy with dopaminergic receptor antagonists, usually resistant to oral medications. Several reports have shown that deep brain stimulation (DBS) of the globus pallidus pars interna (GPi) might be effective in TD, but the overall level of evidence remains limited to case reports or small case series.

OBJECTIVES

We sought to summarize the collective evidence in support of GPi-DBS for TD using a meta-analytic approach.

METHODS

We searched PubMed for human studies reporting tardive dystonia cases treated with GPi-DBS that reported the validated Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) as outcome measure. Data extracted were reviewed for risk of bias. Then, through linear mixed effects modeling of the percent improvement seen on an individual level, we estimated the average improvement effect varying by study.

RESULTS

The searching strategy resulted in a total of n = 78 studies, which were screened for eligibility criteria resulting in the inclusion of n = 14 studies, yielding 134 TD patients for the final analyses. The overall estimate improvement in the BFMDRS after GPi-DBS was 66.88 ± 11.96%. The review of individual case reports indicated rare worsening (n = 4) or lack of improvement (n = 3) following GPi-DBS.

CONCLUSIONS

Bilateral GPi-DBS can be an effective therapeutic option for severe cases of TD resistant to oral pharmacological therapies, even though rare cases of symptom worsening or lack of improvement have also been reported.

Staged bilateral pallidotomy for dystonic camptocormia: case report

Camptocormia is a rare, involuntary movement disorder, presenting as truncal flexion while standing or walking, and is mainly observed as a feature of Parkinson's disease (PD) and primary dystonia. Deep brain stimulation (DBS) of the globus pallidus internus is effective for refractory camptocormia observed with PD or dystonia. However, the effectiveness of pallidotomy for camptocormia has not been investigated. The authors report the case of a 38-year-old man with anterior truncal bending that developed when he was 36 years old. Prior to the onset of the symptom, he had been taking antipsychotic drugs for schizophrenia. There were no features of PD; the symptom severely interfered with his walking and daily life. He was given anticholinergics, clonazepam, and botulinum toxin injections, which did not result in much success. Because of the patient's unwillingness to undergo implantation of a hardware device, he underwent staged bilateral pallidotomy with complete resolution for a diagnosis of tardive dystonic camptocormia. The Burke-Fahn-Marsden dystonia rating scale subscore for the trunk before and after bilateral pallidotomy was 3 and 0, respectively. No perioperative adverse events were observed. Effects have persisted for 18 months. Bilateral pallidotomy can be a treatment option for medically refractory dystonic camptocormia without the need for device implantation.

Management of common adverse effects of antipsychotic medications

The benefits of antipsychotic medications are sometimes obscured by their adverse effects. These effects range from relatively minor tolerability issues (e.g., mild sedation or dry mouth) to very unpleasant (e.g., constipation, akathisia, sexual dysfunction) to painful (e.g., acute dystonias) to disfiguring (e.g., weight gain, tardive dyskinesia) to life-threatening (e.g., myocarditis, agranulocytosis). Importantly, adverse effect profiles are specific to each antipsychotic medication and do not neatly fit into first- and second-generation classifications. This paper reviews management strategies for the most frequent side effects and identifies common principles intended to optimize net antipsychotic benefits. Only use antipsychotics if the indication is clear; only continue antipsychotics if a benefit is discernible. If an antipsychotic is providing substantial benefit, and the adverse effect is not life-threatening, then the first management choice is to lower the dose or adjust the dosing schedule. The next option is to change the antipsychotic; this is often reasonable unless the risk of relapse is high. In some instances, behavioral interventions can be tried. Finally, concomitant medications, though generally not desirable, are necessary in many instances and can provide considerable relief. Among concomitant medication strategies, anticholinergic medications for dystonias and parkinsonism are often effective; beta-blockers and anticholinergic medications are useful for akathisia; and metformin may lead to slight to moderate weight loss. Anticholinergic drops applied sublingually reduce sialorrhea. Usual medications are effective for constipation or dyslipidemias. The clinical utility of recently approved treatments for tardive dyskinesia, valbenazine and deutetrabenazine, is unclear.

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.