Clozapine Treatment in Oromandibular Dystonia

Movement disorders of the mouth: a review of the common phenomenologies

Movement disorders of the mouth encompass a spectrum of hyperactive movements involving the muscles of the orofacial complex. They are rare conditions and are described in the literature primarily in case reports originating from neurologists, psychiatrists, and the dental community. The focus of this review is to provide a phenomenological description of different oral motor disorders including oromandibular dystonia, orofacial dyskinesia and orolingual tremor, and to offer management strategies for optimal treatment based on the current literature. A literature search of full text studies using PubMed/Medline and Cochrane library combined with a manual search of the reference lists was conducted until June 2021. Results from this search included meta-analyses, systematic reviews, reviews, clinical studies, case series, and case reports published by neurologists, psychiatrists, dentists and oral and maxillofacial surgeons. Data garnered from these sources were used to provide an overview of most commonly encountered movement disorders of the mouth, aiding physicians in recognizing these rare conditions and in initiating appropriate therapy.

Treatment of dystonia and tics

Treatment of dystonia and tics continues to evolve. In dystonia, while oral agents such as benzodiazepines, baclofen and anticholinergics remain in use, botulinum toxin (BoNT) continues to be regarded as the treatment of choice for focal and segmental dystonia, but new preparations are being studied. While deep brain stimulation (DBS) has typically focused on targeting the globus pallidus internus (GPi) when treating dystonia, more recent research has expanded the targets to include subthalamic nucleus (STN) and other targets. In addition to DBS, thalamotomies continue to show therapeutic benefit in focal hand dystonias. Treatment of tics includes a growing armamentarium of options besides the three FDA-approved drugs, all dopamine receptor blockers (haloperidol, pimozide and aripiprazole). Because of lower risk of adverse effects, dopamine depleters (e.g. tetrabebazine, deutetrabenazine, and valbenazine), along with novel D1 receptor antagonists, are currently studied as treatment alternatives in patients with tics. Practice guidelines for the treatment of tics and Tourette syndrome have been recently updated. Data regarding the use of DBS in treatment of tics remains relatively sparse, but international registries have expanded our understanding of the effect of stimulation at several targets.

Cortical Silent Period Reveals Differences Between Adductor Spasmodic Dysphonia and Muscle Tension Dysphonia

BACKGROUND

The pathophysiology of adductor spasmodic dysphonia (AdSD), like other focal dystonias, is largely unknown.

OBJECTIVE

The purposes of this study were to determine (a) cortical excitability differences between AdSD, muscle tension dysphonia (MTD), and healthy controls; (b) distribution of potential differences in cranial or skeletal muscle; and (c) if cortical excitability measures assist in the differential diagnosis of AdSD and MTD.

METHODS

Ten participants with adductor spasmodic dysphonia, 8 with muscle tension dysphonia, and 10 healthy controls received single and paired pulse transcranial magnetic stimulation (TMS) to the primary motor cortex contralateral to tested muscles, first dorsal interosseus (FDI), and masseter. We tested the hypothesis that cortical excitability measures in AdSD would be significantly different from those in MTD and healthy controls. In addition, we hypothesized that there would be a correlation between cortical excitability measures and clinical voice severity in AdSD.

RESULTS

Cortical silent period duration in masseter and FDI was significantly shorter in AdSD than MTD and healthy controls. Other measures failed to demonstrate differences.

CONCLUSION

There are differences in cortical excitability between AdSD, MTD, and healthy controls. These differences in the cortical measure of both the FDI and masseter muscles in AdSD suggest widespread dysfunction of the GABAB mechanism may be a pathophysiologic feature of AdSD, similar to other forms of focal dystonia. Further exploration of the use of TMS to assist in the differential diagnosis of AdSD and MTD is warranted.

Clozapine and tardive movement disorders: a review

BACKGROUND

Tardive syndromes (TS) arise from long term exposure to dopamine receptor blocking agents. Clozapine has been considered to have low risk of causing new onset TS and is considered as a treatment option in patients with TS.

AIM

This review evaluates the usefulness of clozapine in patients with TS and occasional reports of clozapine causing TS.

METHODOLOGY

Electronic searches were carried out using the search engines of PUBMED, Science direct and Google Scholar databases. All reports describing use of clozapine in management of TS, monitoring of TS while on clozapine and onset of TS after initiation of clozapine were identified.

RESULTS

Fifteen trials and 28 case series/case reports describe the use of clozapine in TS. Most of these reports show that clozapine is useful in patients with TS, in the dose range of 200-300 mg/day and the beneficial effect is seen within 4-12 weeks of initiation. One case series and two case reports described clozapine withdrawal emergent dyskinesias suggesting a masking role of clozapine. One trial, three case series and two case reports describe beneficial effects of clozapine on long standing neurological syndromes. There is relatively less literature (2 trials and 15 case series/reports) describing the emergence of TS with clozapine.

CONCLUSION

Evidence of beneficial effects of clozapine in TS is greater than its role in causation/worsening of TS. Hence, clozapine should be considered in symptomatic patients who develop TS while receiving other antipsychotics. Further research on mechanism of TS and clozapine effect on TS is required.

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.

Meige syndrome: what's in a name?

Frequently, blepharospasm is associated with involuntary movements of the platysma, lower face and masticatory muscles. Similarly, masticatory dystonia may occur in isolation or in combination with dystonia of other cranial and cervical muscles. The non-possessive and possessive forms of Meige and Brueghel syndromes have been variably and imprecisely ascribed to various anatomical variations of craniocervical dystonia. Herein, the origin of eponymic terms as applied to craniocervical dystonia is reviewed as support for proposed elimination of these eponyms from clinical usage. Although the term "segmental craniocervical dystonia" more accurately captures the combination of blepharospasm and dystonia of other head and neck muscles, delineation of craniocervical subphenotypes is essential for etiological/genetic and treatment studies. To conclude, the clinical features, epidemiology, pathophysiology and therapeutic management of segmental craniocervical dystonia are examined with a particular focus on "blepharospasm-plus" subphenotypes.

Oromandibular dystonia

Oromandibular dystonia (OMD) is a rare neuromuscular disorder characterized by involuntary repetitive muscular contraction affecting different parts of the oromandibular region. Its various physical manifestations can be extremely debilitating and socially disabling to affected patients. To date, there is no commonly accepted set of diagnostic criteria nor well-defined management pathways. This paper aims to discuss some aspects of clinical manifestations, diagnostic criteria, neurological mechanisms, and treatment options for OMD, with illustrations from 6 clinical cases.

A comparison of jaw-closing and jaw-opening idiopathic oromandibular dystonia

Oromandibular dystonia (OMD) is a form of focal dystonia that affects masticatory, lower facial, and lingual muscles. We compared the clinical variables and response to treatment between patients with idiopathic jaw-closure C-OMD (n = 11) and jaw-opening dystonia O-OMD (n = 12) seen in our Movement Disorders clinic over the last 10 years. The co-existence of dystonia in other regions and sensory tricks were significantly more prevalent in O-OMD (P = 0.049 and 0.03, respectively). Male gender, orobuccolingual dyskinesias (facial grimacing, lip biting, tongue dyskinesias, platysma contractions and bruxism) and better response to botulinum toxin injections were more frequent in C-OMD but remained a trend.