Pharmacological study in Meige's syndrome with predominant blepharospasm

Electrophysiological signatures predict clinical outcomes after deep brain stimulation of the globus pallidus internus in Meige syndrome

OBJECTIVE

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been shown to be a safe and effective alternative therapy for ameliorating medically refractory primary Meige syndrome. However, the associations between DBS target position and surrounding electrophysiological properties as well as patients' clinical outcomes remains largely unknown. In a large number of patients, we investigated electrophysiological features around stimulation targets and explored their roles in predicting clinical outcomes following bilateral GPi-DBS.

METHODS

The locations of DBS active contacts along the long axis of the GPi in a standard space were calculated and compared among three groups with different clinical outcomes. The firing rates of individual neurons within the GPi were calculated for each patient and compared across the three groups.

RESULTS

Compared with the bad group (poor clinical outcome), active contacts in the good group (good clinical outcome) and the best group (best clinical outcome) were located in the more posterior GPi. The average firing rates in the good and best groups were significantly higher than in the bad group, and this difference was pronounced within the ventral GPi. For the bad group, the average firing rates were significantly lower in the ventral than in the dorsal GPi.

CONCLUSIONS

This study suggests that DBS of the posterior GPi may produce better clinical outcomes during primary Meige syndrome treatment and that higher GPi neuronal activity, particularly within the ventral part, can be used as a biomarker to guide DBS electrode implantation during surgery.

Dopamine Receptor Agonist Treatment of Idiopathic Dystonia: A Reappraisal in Humans and Mice

Although dystonia is often associated with abnormal dopamine neurotransmission, dopaminergic drugs are not currently used to treat dystonia because there is a general view that dopaminergic drugs are ineffective. However, there is little conclusive evidence to support or refute this assumption. Therefore, to assess the therapeutic potential of these compounds, we analyzed results from multiple trials of dopamine receptor agonists in patients with idiopathic dystonias and also tested the efficacy of dopamine receptor agonists in a mouse model of generalized dystonia. Our results suggest that dopamine receptor agonists were effective in some, but not all, patients tested. Further, the mixed D1/D2 dopamine receptor agonist apomorphine was apparently more effective than subtype selective D2 dopamine receptor agonists. However, rigorously controlled trials are still needed. In a mouse model of dystonia, a selective D1 dopamine receptor agonist was not effective while a selective D2 dopamine receptor had modest efficacy. However, when combined, these receptor-selective agonists acted synergistically to ameliorate the dystonia. Coactivation of D1 and D2 dopamine receptors using apomorphine or by increasing extracellular concentrations of dopamine was also effective. Thus, results from both clinical trials and tests in mice suggest that coactivation of D1 and D2 dopamine receptors may be an effective therapeutic strategy in some patients. These results support a reconsideration of dopamine receptors as targets for the treatment of dystonia, particularly because recent genetic and diagnostic advances may facilitate the identification of the subtypes of dystonia patients who respond and those who do not.

Understanding dystonia: diagnostic issues and how to overcome them

ABSTRACT The diagnosis and treatment of dystonia are challenging. This is likely due to gaps in the complete understanding of its pathophysiology, lack of animal models for translational studies, absence of a consistent pathological substrate and highly variable phenotypes and genotypes. The aim of this review article is to provide an overview of the clinical, neurophysiological and genetic features of dystonia that can help in the identification of this movement disorder, as well as in the differential diagnosis of the main forms of genetic dystonia. The variation of penetrance, age of onset, and topographic distribution of the disease in carriers of the same genetic mutation indicates that other factors – either genetic or environmental – might be involved in the development of symptoms. The growing knowledge of cell dysfunction in mutants may give insights into more effective therapeutic targets.

The Dystonias

Dystonia is a difficult problem for both the clinician and the scientist. It is sufficiently common to be seen by almost all physicians, yet uncommon enough to prevent any physician from gaining broad experience in its diagnosis and treatment. Each case represents a difficult challenge even to the specialist. The basic scientist is faced with investigating a disorder that is without relevant animal models and which is so rare that obtaining suitable tissue for study is a major obstacle. Dystonia may be idiopathic, or associated with lesions from many sources, including a variety of rare diseases. If idiopathic, it may be genetically transmitted or sporadic. If genetically transmitted, it may be generalized or focal, with symptoms varying in different members of the same family. It may be refractory to treatment, or it may respond to any one of a number of individual drugs that have very different mechanisms of action. For idiopathic dystonias, no clear method of genetic transmission has been established and no consistent pathology identified.

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.

Orofacial pain and sensory disorders in the elderly

Many orofacial pain conditions occur in the elderly. Specifically,this article reviews the prevalence of general and orofacial-related pain in the elderly. The authors also describe and discuss the likely disorders and diseases that produce facial pain and burning pain in the mouth. They do not cover jaw joint pain, oral sores, or ulceration-induced pain, as these conditions are better discussed in the context of arthritis and oral pathologies of the mouth. The authors discuss oral motor disorders, myogenous pain, vascular pain, headaches, trigeminal neuralgia, trigeminal neuropathic dis-ease, postherpetic neuralgia, burning mouth syndrome, and occlusal dysesthesia.

Treatment of inferior lateral pterygoid muscle dystonia with zolpidem tartrate, botulinum toxin injections, and physical self-regulation procedures: a case report

The following case report depicts the management of a patient suffering with a jaw opening oromandibular dystonia using a combination of botulinum toxin injections, zolpidem, and relaxation procedures. Eventually the botulinum toxin injections were eliminated, and the patient was maintained with only zolpidem and relaxation procedures.

Effect of clonazepam treatment on antipsychotic drug-induced Meige syndrome and changes in plasma levels of GABA, HVA, and MHPG during treatment

We demonstrated the effect of clonazepam (2 mg/day) on Meige syndrome in two schizophrenic patients under continuous treatment with antipsychotic drugs, and changes in the plasma levels of gamma-aminobutyric acid (GABA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) in these cases. The plasma levels of HVA and MHPG during treatment with clonazepam were decreased in the responder, while not changed in the non-responder to clonazepam. A difference between the responder and the non-responder was not found in the plasma GABA levels. These results suggest that hyperactivities of the central dopaminergic and noradrenergic neurones are involved in the pathophysiology of Meige syndrome.

Reduction of Parkinsonian signs in patients with Parkinson's disease by dopaminergic versus anticholinergic single-dose challenges

We investigated the effect of an anticholinergic (biperiden) and a dopamine agonist (apomorphine) on tremor, rigidity, and akinesia in patients with idiopathic Parkinson's disease. In a standardized, crossover study design 17 patients received single-dose challenges of 5 mg biperiden intravenously and a previously determined dose of apomorphine subcutaneously on 2 consecutive days. Resting (RT), postural (PT), and action tremor (AT) were assessed using spectral analysis of accelerometer data, and Unified Parkinson's Disease Rating Scale (UPDRS) scores for rigidity and akinesia were determined before and after administration of the study drug. Both single-dose challenges significantly reduced the amplitude of RT, PT, and AT, but only apomorphine significantly reduced UPDRS scores for rigidity and akinesia. In only one patient was tremor reduced by the dopamine agonist but not by the anticholinergic. We found that anticholinergic and dopaminergic agents are both effective in reducing tremor in IPD, and there was no evidence for a selective anticholinergic responsiveness of parkinsonian tremor. Akinesia and rigidity, on the other hand, were not improved by biperiden. We therefore conclude that dopaminergic substances are as effective as anticholinergics in patients with parkinsonian tremor and additionally improve other parkinsonian signs.

Life-threatening cranial dystonia following trihexyphenidyl withdrawal

A 64-year-old woman with blepharospasm, sustained clenching of the jaw, antecollis, and a strained, high-pitched phonation continued chronic trihexyphenidyl therapy despite the lack of any obvious benefit. Abrupt, accidental withdrawal of trihexyphenidyl triggered severe exacerbation of the cranial dystonia associated with inspiratory stridor and acute respiratory difficulties, prompting emergency admission. On indirect laryngoscopy, hyperadduction of the vocal folds was not the cause of the upper airway obstruction. A more likely cause of the inspiratory obstruction appeared to be forward bending of the neck combined with mouth-clenching spasms. Reinstitution of intravenous anticholinergic medication provided relatively prompt relief. We caution against abrupt interruption of anticholinergics in patients with severe segmental cranial dystonia, even in those cases in which no benefit is apparent to observers.