Diagnosis and classification of blepharospasm: Recommendations based on empirical evidence

Definition and Classification of Dystonia

Dystonia is a movement disorder with varied clinical features and diverse etiologies. Here we present a revision of the 2013 consensus definition and classification of dystonia in light of subsequent publications and experience with its application during the last decade. A panel of movement disorder specialists with expertise in dystonia reviewed the original document and proposed some revision. There was broad consensus to retain the definition of dystonia with only minor clarifications to the wording. Dystonia is defined as a movement disorder characterized by sustained or intermittent abnormal movements, postures, or both. Dystonic movements and postures are typically patterned and repetitive and may be tremulous or jerky. They are often initiated or worsened by voluntary action and frequently associated with overflow movements. The two-axis structure for classification of the many different presentations of dystonia was also retained, with some revision. Axis I summarizes key clinical characteristics of dystonia, including age at onset, family history, body distribution, temporal dimensions, phenomenology, and whether dystonia is isolated or combined with other neurological or medical problems. Axis II organizes information regarding its etiological basis, including genetic, acquired, and anatomical, and common disease mechanisms. This consensus provides an update to the original definition and classification of dystonia with the aim of facilitating its clinical recognition and management. The revision retains the essence of the original proposal and aims particularly to provide a structure facilitating a uniform implementation. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Association between functional alterations and specific transcriptional expression patterns in craniocervical dystonia

PURPOSE

Craniocervical dystonia (CCD) is a large-scale network disorder that involves functional changes in multiple brain regions. However, the association between these functional changes and the underlying molecular mechanisms has not been explored.

OBJECTIVE

We aimed to characterize the molecular changes associated with the imaging-defined functional architecture of the brain in CCD.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) data were obtained from 146 patients with CCD and 137 healthy controls (HCs). Differences in the amplitude of low-frequency fluctuations (ALFF), fractional ALFF (fALFF), and regional homogeneity (ReHo) were compared between groups. Transcriptomic data were obtained from the Allen Human Brain Atlas to identify the gene expression patterns underlying the affected functional architecture in CCD using partial least squares regression.

RESULTS

Compared to HCs, patients with CCD showed common functional alterations, mainly in the left middle occipital gyrus, right middle occipital gyrus, right calcarine, right precentral gyrus, and left postcentral gyrus. These functional alteration patterns were positively associated with 1763 genes (including five risk genes for dystonia) enriched for synaptic signaling, regulation of trans-synaptic signaling, and neuronal systems, while they were negatively associated with 2318 genes (including eight risk genes for dystonia), which were enriched for monoatomic cation transport, DNA damage response and neurodevelopment.

CONCLUSIONS

Our study reveals a genetic pathological mechanism explaining CCD-related brain functional changes.

[Comparative analysis of the effectiveness of Botulinum toxin type A - hemagglutinin preparations of the Relatox and Botox complex in the treatment of patients with primary idiopathic blepharospasm]

OBJECTIVE

To analyze the effectiveness of Relatox (Botulinum toxin type A - hemagglutinin complex) in comparison with Botox in the treatment of primary idiopathic blepharospasm.

MATERIAL AND METHODS

The study included clinical data for 21 patients with blepharospasm who were treated by botulinum therapy with Botox and Relatox for 3 years. The research method is a one-step retrospective analysis of medical data. Injections were carried out with a 3-month interval. On the 6th cycle, the drug was switched to Relatox. The clinical efficacy of the drugs was assessed using an 8-point Jankovich evaluation scale: the average values before the injection and 14 days after it were compared for each procedure.

RESULTS

Mean Jankovich scale scores decreased 2.5-fold for all cycles by the second week after the procedure (4.95 pre-injection vs. 1.8 post-injection), and the mean paired Student's T-criterion for all injections was 7.14 (with a critical value of 2.021 and a significance level of p=0.05). The mean paired Student's T-criterion for Botox was -6.63 and for Relatox -7.5 (with a critical value of 2.021 and a significance level of p=0.05), indicating a high efficacy of both drugs, slightly higher for Relatox.

CONCLUSION

A consistent trend of increasing efficacy with regular botulinum toxin injections and greater efficacy of Relatox compared to Botox in the treatment of patients with primary idiopathic blepharospasm has been demonstrated.

Progressive thalamic nuclear atrophy in blepharospasm and blepharospasm-oromandibular dystonia

The thalamus is considered a key region in the neuromechanisms of blepharospasm. However, previous studies considered it as a single, homogeneous structure, disregarding potentially useful information about distinct thalamic nuclei. Herein, we aimed to examine (i) whether grey matter volume differs across thalamic subregions/nuclei in patients with blepharospasm and blepharospasm-oromandibular dystonia; (ii) causal relationships among abnormal thalamic nuclei; and (iii) whether these abnormal features can be used as neuroimaging biomarkers to distinguish patients with blepharospasm from blepharospasm-oromandibular dystonia and those with dystonia from healthy controls. Structural MRI data were collected from 56 patients with blepharospasm, 20 with blepharospasm-oromandibular dystonia and 58 healthy controls. Differences in thalamic nuclei volumes between groups and their relationships to clinical information were analysed in patients with dystonia. Granger causality analysis was employed to explore the causal effects among abnormal thalamic nuclei. Support vector machines were used to test whether these abnormal features could distinguish patients with different forms of dystonia and those with dystonia from healthy controls. Compared with healthy controls, patients with blepharospasm exhibited reduced grey matter volume in the lateral geniculate and pulvinar inferior nuclei, whereas those with blepharospasm-oromandibular dystonia showed decreased grey matter volume in the ventral anterior and ventral lateral anterior nuclei. Atrophy in the pulvinar inferior nucleus in blepharospasm patients and in the ventral lateral anterior nucleus in blepharospasm-oromandibular dystonia patients was negatively correlated with clinical severity and disease duration, respectively. The proposed machine learning scheme yielded a high accuracy in distinguishing blepharospasm patients from healthy controls (accuracy: 0.89), blepharospasm-oromandibular dystonia patients from healthy controls (accuracy: 0.82) and blepharospasm from blepharospasm-oromandibular dystonia patients (accuracy: 0.94). Most importantly, Granger causality analysis revealed that a progressive driving pathway from pulvinar inferior nuclear atrophy extends to lateral geniculate nuclear atrophy and then to ventral lateral anterior nuclear atrophy with increasing clinical severity in patients with blepharospasm. These findings suggest that the pulvinar inferior nucleus in the thalamus is the focal origin of blepharospasm, extending to pulvinar inferior nuclear atrophy and subsequently extending to the ventral lateral anterior nucleus causing involuntary lower facial and masticatory movements known as blepharospasm-oromandibular dystonia. Moreover, our results also provide potential targets for neuromodulation especially deep brain stimulation in patients with blepharospasm and blepharospasm-oromandibular dystonia.

An Exploratory, Randomized, Double-Blind Clinical Trial of Dipraglurant for Blepharospasm

BACKGROUND

Blepharospasm is treated with botulinum toxin, but obtaining satisfactory results is sometimes challenging.

OBJECTIVE

The aim is to conduct an exploratory trial of oral dipraglurant for blepharospasm.

METHODS

This study was an exploratory, phase 2a, randomized, double-blind, placebo-controlled trial of 15 participants who were assigned to receive a placebo or dipraglurant (50 or 100 mg) and assessed over 2 days, 1 and 2 hours following dosing. Outcome measures included multiple scales rated by clinicians or participants, digital video, and a wearable sensor.

RESULTS

Dipraglurant was well tolerated, with no obvious impact on any of the measurement outcomes. Power analyses suggested fewer subjects would be required for studies using a within-subject versus independent group design, especially for certain measures. Some outcome measures appeared more suitable than others.

CONCLUSION

Although dipraglurant appeared well tolerated, it did not produce a trend for clinical benefit. The results provide valuable information for planning further trials in blepharospasm. © 2024 International Parkinson and Movement Disorder Society.

An Empirical Comparison of Commonly Used Universal Rating Scales for Dystonia

Background

There are several widely used clinical rating scales for documenting the severity and distribution of various types of dystonia.

Objectives

The goal of this study was to evaluate the performance of the most commonly used scales in a large group of adults with the most common types of isolated dystonia.

Methods

Global Dystonia Rating Scale (GDRS) and the Burke-Fahn-Marsden Dystonia Rating Scale (BFM) scores were obtained for 3067 participants. Most had focal or segmental dystonia, with smaller numbers of multifocal or generalized dystonia. These scales were also compared for 209 adults with cervical dystonia that had Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores and 210 adults with blepharospasm that had Blepharospasm Severity Scale (BSRS) scores.

Results

There were strong correlations between the GDRS and BFM total scores (r = 0.79) and moderate correlations for their sub scores (r > 0.5). Scores for both scales showed positive skew, with an overabundance of low scores. BFM sub-scores were not normally distributed, due to artifacts caused by the provoking factor. Relevant sub-scores of the GDRS and BFM also showed moderate correlations with the TWSTRS (r > 0.5) for cervical dystonia and the BSRS (r > 0.5) for blepharospasm.

Conclusions

The BFM is more widely used than the GDRS, but these results suggest the GDRS may be preferable for focal and segmental dystonias. The overabundance of very low scores for both scales highlights challenges associated with discriminating very mild dystonia from other abnormal movements or variants of normal behavior.

Clinical features of dystonia and the science of classification

This chapter describes advances in understanding the clinical features of dystonia since initial clinical recognition and its organization into a coherent and systematic clinical set. The clinical features of dystonia were at first considered an odd neurological movement disorder. Etymology of the word misleadingly underlined muscle tone. The main clinical features of dystonia were recognized gradually. They encompass dystonic movements, dystonic postures, alleviating maneuvers, overflow and mirroring. These features are observed in patients who present a variety of syndromes where dystonia occurs in isolation or combined with other movement disorders, or with other neurologic or systemic features. A large number of syndromic combinations is observed in the clinic and some of the syndomes are highlighted here. Practitioners are required to exert dedicated skills to recognize dystonia and correctly diagnose and classify their patients.

Anatomical categorization of isolated non-focal dystonia: novel and existing patterns using a data-driven approach

According to expert consensus, dystonia can be classified as focal, segmental, multifocal, and generalized, based on the affected body distribution. To provide an empirical and data-driven approach to categorizing these distributions, we used a data-driven clustering approach to compare frequency and co-occurrence rates of non-focal dystonia in pre-defined body regions using the Dystonia Coalition (DC) dataset. We analyzed 1,618 participants with isolated non-focal dystonia from the DC database. The analytic approach included construction of frequency tables, variable-wise analysis using hierarchical clustering and independent component analysis (ICA), and case-wise consensus hierarchical clustering to describe associations and clusters for dystonia affecting any combination of eighteen pre-defined body regions. Variable-wise hierarchical clustering demonstrated closest relationships between bilateral upper legs (distance = 0.40), upper and lower face (distance = 0.45), bilateral hands (distance = 0.53), and bilateral feet (distance = 0.53). ICA demonstrated clear grouping for the a) bilateral hands, b) neck, and c) upper and lower face. Case-wise consensus hierarchical clustering at k = 9 identified 3 major clusters. Major clusters consisted primarily of a) cervical dystonia with nearby regions, b) bilateral hand dystonia, and c) cranial dystonia. Our data-driven approach in a large dataset of isolated non-focal dystonia reinforces common segmental patterns in cranial and cervical regions. We observed unexpectedly strong associations between bilateral upper or lower limbs, which suggests that symmetric multifocal patterns may represent a previously underrecognized dystonia subtype.

What Is Hemidystonia?

Background

Hemidystonia is defined as dystonia restricted to one side of the body. It is traditionally believed to result from a lesion in the contralateral hemisphere.

Objectives

To describe a series of hemidystonia patients without lesions on brain imaging.

Methods

We searched for individuals with potential hemidystonia who were included in the Dystonia Coalition or Movement Disorder Society Genetic mutation database (MDSgene), and conducted a systematic review.

Results

We found 10 individuals classified as hemidystonia or with homolateral limb dystonia among 3696 cases enrolled by the Dystonia Coalition, 9 cases in MDSgene, and one idiopathic case in the literature. None had evidence of a brain lesion. Body distributions used to define hemidystonia varied considerably and were not always restricted to one side of the body.

Conclusions

Hemidystonia may be idiopathic or genetic, without any obvious brain lesion. The varied use of the term suggests the need for more specific clinical criteria to define "half the body."