The phenomenology of the geste antagoniste in primary blepharospasm and cervical dystonia

Phenotypic comparison between combined dystonia-parkinsonism and idiopathic adult-onset dystonia

The clinical characteristics of dystonia occurring in association with sporadic neurodegenerative parkinsonism have not been systematically explored or compared with those of idiopathic adult-onset dystonia. This study aims to compare demographic and clinical features, including the distribution of dystonia at onset, dystonia-associated features, and the propensity for spread between patients with combined dystonia-parkinsonism and those with idiopathic adult-onset dystonia. Patients were selected from the Italian Dystonia Registry. The study cohort included 130 patients with combined dystonia-parkinsonism and 355 age- and sex-matched patients with isolated adult-onset idiopathic dystonia. The comparison between combined dystonia-parkinsonism and idiopathic dystonia revealed differences in the distribution of dystonia across body regions, with non-task-specific upper limb dystonia, lower limb dystonia, and trunk dystonia occurring more frequently in patients with combined dystonia-parkinsonism. Additionally, this group exhibited a lower frequency of head tremor, eye symptoms associated with blepharospasm, and sensory tricks, alongside a comparable frequency of neck pain related to cervical dystonia and a family history of dystonia or tremor. The clinical presentation of dystonia differs between combined dystonia-parkinsonism and idiopathic dystonia, especially in terms of the body regions affected. These differences underscore the necessity for additional research and suggest underlying pathophysiological disparities between etiological categories that could significantly influence future diagnostics and therapeutic approaches.

Dystonia: pathophysiology and the role of acupuncture in treatment

Dystonia is a complex neurological disorder characterized by involuntary muscle contractions, abnormal postures, and repetitive movements, which can lead to significant functional impairment and reduced quality of life. The disorder's pathophysiology involves a range of factors including genetic mutations, neurochemical imbalances, and structural abnormalities in the brain. Acupuncture has emerged as a promising complementary treatment for various types of dystonia, including post-stroke, cerebral palsy (CP)-related, limb, and cervical dystonia, as well as other hyperkinetic movement disorders. Clinical studies indicate that acupuncture may help to alleviate symptoms, decrease muscle spasticity, and improve overall patient outcomes. However, the effectiveness of acupuncture can vary depending on the specific type and severity of dystonia, with some studies reporting significant improvements, while others show more modest results. The variability in treatment response highlights the need for more robust research to better understand the mechanisms underlying acupuncture's effects and to develop standardized treatment protocols. The aim of this review is to provide a comprehensive overview of dystonia's pathophysiology and to assess the current evidence on the role of acupuncture in its treatment, identifying areas in which further research is needed to optimize therapeutic approaches.

Risk of Spreading in Adult-onset Dystonia

Background

Adult-onset dystonia can also spread to other parts of the body, although it is not as common as childhood-onset dystonia.

Objective

Our study aimed to examine the clinical factors determining spreading patterns in all adult-onset dystonia types.

Methods

We retrospectively analyzed the medical records of patients with a diagnosis of isolated dystonia followed longitudinally at our center. We included patients reporting symptom onset after 18 years. We then compared the clinical factors between groups with and without spreading.

Results

Among 434 patients (396 focal, 29 segmental, and nine generalized onset dystonia. mean follow-up of 8.6 ± 7.8 years), 48 (11.1%) experienced spread of dystonia, with 37 progressing from focal to segmental, two from focal to generalized, two from segmental to generalized, and seven from focal to segmental to generalized dystonia. Blepharospasm was the most common focal dystonia noted to spread, followed by oromandibular dystonia, cervical dystonia, laryngeal dystonia, and upper extremity dystonia, in decreasing order. A spreading pattern was observed in approximately one in 10 dystonia patients, and the spreading was more frequent in the segmental dystonia group. While there was no difference between the spreading groups regarding sensory tricks, tremor, and gender, family history was more common in the non-spreading group (p = 0.023). Older age at onset was independently associated with increased odds of spreading (hazards ratio: 1.054, p < 0.001, B = 0.053).

Conclusion

Although risk factors for spread are variable, the underlying mechanisms are not fully known. Genetic factors may be possibly related to the spread, and future studies are needed on this subject.

Longitudinal assessment of blepharospasm severity in patients with long disease duration

INTRODUCTION

Blepharospasm (BSP) represents one of the most common idiopathic adult-onset dystonia. A few longitudinal observations indicated progression and worsening of BSP severity within 16 years of onset. Information is lacking about the trend of BSP severity in the later stages of the disease.

METHODS

The study comprised 15 women and 3 men that underwent a standardized video protocol at two time points: 14 ± 9 years after BSP onset and 11 ± 2 years later. BSP severity was rated by the Blepharospasm Severity Rating Scale (BSRS). Two independent observers reviewed 36 videos in a pseudo-randomized order, yielding satisfactory agreement.

RESULTS

Mean total severity score was 7.6 ± 3.9 years at baseline, 6.4 ± 2.5 at the last examination (p = 0.14). The last video examination showed a stable BSRS score in 14/18 patients, while the score of 4 patients decreased by two points or more, due to disappearance (n.3) or reduction (n.1) of prolonged spasms with complete rim closure. Over the long term, the BoNT dosage increased in those who improved, but remained stable in the other patients. On follow-up examination, dystonia spread to the lower face or neck in two new patients. No significant correlations emerged between disease duration and BSP severity. The presence of sensory trick significantly correlated with disease duration but not with BSP severity.

DISCUSSION

This study provides novel information on the long-term prognosis in patients with idiopathic BSP, showing that severity of BSP may not worsen in the later stages of the disease.

How to face the hemifacial spasm: challenges and misconceptions

Hemifacial spasm (HFS) is characterised by intermittent, brief or sustained, repetitive contractions of the muscles innervated by one facial nerve. It is one of the most frequent movement disorders affecting the face. However common and allegedly straightforward to diagnose, it might reveal as a challenge for clinicians in various situations. Indeed, it often needs prior exclusion of many other movement disorders affecting the face, with frequent phenomenological overlaps with blepharospasm, post-facial palsy, facial motor tics, etc. The clinical diagnosis shall be supported by modern brain imaging techniques, and sometimes electromyography, as some particular aetiologies may require specific treatment. Primary forms are associated with vascular compression of the ipsilateral seventh cranial nerve, whereas secondary forms can be caused by any injury occurring on the facial nerve course. This article proposes a global and organised approach to the diagnosis, and the ensuing therapeutic options, as many practitioners still use some inefficient medications when they encounter a case of facial spasm.

Treatment of strabismus and blepharospasm with Botox (onabotulinumtoxinA): Development, insights, and impact

Strabismus, deviation of the ocular alignment, can adversely affect quality of life and activities of daily living. Surgery was the prior standard of care for strabismus, but up to 40% of patients required additional surgeries. This need for more effective and less invasive treatment, along with the convergence of other events such as the development of electromyography, purification of botulinum toxin A, and the finding that injection of botulinum toxin type A could paralyze the hind limbs of chicks, led Dr. Alan Scott to investigate injection of his formulation for strabismus. The positive results of initial trials in monkeys segued to human trials with observations of alignment improvements and few adverse events. The success of botulinum toxin type A in the treatment of strabismus led to interest in its use to treat other skeletal muscles, particularly in blepharospasm, a type of focal dystonia involving eyelid spasms and involuntary eye closure that lacked an effective pharmacological treatment. Patient groups helped to increase awareness of this novel treatment, and results from clinical trials confirmed its effectiveness. Dr. Scott's formulation, then known as Oculinum, received its first Food and Drug Administration approvals in 1989 for strabismus and blepharospasm. Allergan acquired Oculinum in 1991, renaming it Botox. These initial uses led to its application in a myriad of other indications as outlined in other articles of this supplement.

Treatment of cervical dystonia with Botox (onabotulinumtoxinA): Development, insights, and impact

Cervical dystonia (CD), the most common focal dystonia encountered in neurologic practice, is a chronic disorder in which the muscles of the neck involuntarily contract and cause abnormal postures and movements of the head, neck, and shoulders. Treatment of CD prior to botulinum toxin was unsatisfactory, as existing therapies often did not improve symptoms. The use of botulinum toxin for CD grew out of its success in treating blepharospasm, another type of focal dystonia. On the basis of results from a double-blind, placebo-controlled trial, onabotulinumtoxinA was approved in 2000 in the US for the treatment of CD in adults in order to alleviate abnormal head position and neck pain. A subsequent large observational trial further demonstrated the effectiveness of onabotulinumtoxinA for CD, showing improvements in various rating scales, physician-reported measures, and profound positive effects on patient quality of life, including in amelioration of pain and improvements in work productivity. In addition, onabotulinumtoxinA treatment also reduced the complications of CD, as patients no longer develop contractures (permanent muscle and tendon shortening from prolonged untreated dystonia), which markedly limited the range of neck motion. The onset of onabotulinumtoxinA treatment also accompanied advances in understanding the functional anatomy of neck muscles, basal ganglia physiology, and video and other recording technology. Following the success of onabotulinumtoxinA in the treatment of CD, its use has been expanded into numerous other therapeutic indications, and these advances stimulated educational and training programs by various neurologic and other medical societies.

Video analysis of patients with blepharospasm and lower face dystonias

Background

Blepharospasm (BSP) is a focal dystonia. There is a lack of standardization in the length of time necessary to get a measure of BSP severity for rating scales.

Objectives

1) Determine the difference between evaluating the number of eye closures in patients with blepharospasm in 1 vs. 2 min. 2) Characterize the prevalence, phenomenology and concordance of sensory trick in subjects with only blepharospasm compared to those with blepharospasm associated with other dystonias of the head.

Methods

Thirty-eight, 2-min-long standardized videos of subjects with BSP without any other dystonias were reviewed (group1). Eye closure rate was measured in 0-60 s vs. 60-120 s. Wilcoxon signed-rank test and Spearman correlation coefficient were used to compare the eye closure rate between these two intervals. An additional 68 standardized videos of subjects with blepharospasm associated with dystonia of the head were reviewed (group2). Presence, phenomenology and concordance between what subjects verbally reported as their sensory trick and what they demonstrated was classified for both groups then qualitatively compared.

Results/conclusion

Eye closure rates between 0-60 s and 0-120 s were not statistically different. There is no added benefit of counting the number of eye closures in 2 min, compared to 1 min, in patients with BSP. Sensory trick was reported by 57% of subjects with BSP and 80% of subjects who have blepharospasm and other dystonias of the head. With 100% and 97% concordance, patients' self-reported sensory trick accurately describes the movements that alleviate their dystonic movements.

Elucidation of the mechanism underlying impaired sensorimotor gating in patients with primary blepharospasm using prepulse inhibition

Objective

We aimed to analyze prepulse inhibition (PPI) impairment of the blink reflex in patients with primary blepharospasm (BSP).

Methods

We recruited 30 BSP patients and 20 gender- and age-matched healthy controls (HCs). Weak electrical stimulation was applied to the right index finger at interstimulus intervals (ISIs) of 120, 200, and 300 ms before the supraorbital nerve stimulation to investigate PPI size [PPI size = (1 - R₂ area at prepulse trials/R₂ area at baseline trials) × 100%].

Results

The prepulse stimulus significantly inhibited the R ₂ component at the three ISIs in both groups, but less inhibition was shown in the BSP group (p < 0.05). In HCs, the prepulse stimulus induced prolonged R ₂ and R _2c latencies at the three ISIs and increased the R ₁ amplitude at ISIs of 120 ms; these changes were absent in BSP patients. In the BSP group, patients with sensory tricks showed better PPI than patients without sensory tricks. Disease duration and motor symptom severity showed no significant correlation with PPI size.

Conclusion

In BSP patients, PPI was impaired while R ₁ facilitation was absent. PPI size did not correlate with the motor symptom severity and disease duration. Patients with sensory tricks showed better PPI than those without sensory tricks.

Adult-Onset Idiopathic Cervical Dystonia

Adult-onset idiopathic focal dystonia is the most common type of primary dystonia, and adult-onset idiopathic cervical dystonia (AOICD) is its most prevalent phenotype. AOICD is an autosomal-dominant disorder with markedly reduced penetrance; clinical expression is dependent on age, sex, and environmental exposure. Motor symptoms at presentation are poorly recognised by non-specialists, leading to long delays in diagnosis. Certain features of history and examination can help diagnose cervical dystonia. There is a relatively high prevalence of anxiety and/or depression, which adversely affects health-related quality of life. Recent studies indicate that patients with AOICD also have disordered social cognition, particularly affecting emotional sensory processing. AOICD can be treated reasonably effectively with botulinum toxin injections, given at 3-month intervals. Oral antidystonic medications are often trialled initially, but are largely ineffective. Comprehensive modern management of patients with AOICD requires recognition of presence of mood disorders, and actively treating the endogenous mood disorder with antidepressant therapy. Botulinum toxin injections alone, no matter how expertly given, will not provide optimal therapy and improved health-related quality of life without an holistic approach to patient management. Increasing evidence indicates that AOICD is a neurophysiological network disorder of GABAergic inhibition, causing a syndrome of dystonia, mood disturbance, and social cognitive dysfunction, with the superior colliculus playing a central role.

Role of supplementary motor area in cervical dystonia and sensory tricks

Sensory trick is a characteristic feature of cervical dystonia (CD), where a light touch on the area adjacent to the dystonia temporarily improves symptoms. Clinical benefit from sensory tricks can be observed before tactile contact is made or even by imagination. The supplementary motor area (SMA) may dynamically interact with the sensorimotor network and other brain regions during sensory tricks in patients with CD. In this study, we examined the functional connectivity of the SMA at rest and during sensory trick performance and imagination in CD patients compared to healthy controls using functional magnetic resonance imaging. The functional connectivity between the SMA and left intraparietal sulcus (IPS) region was lower in CD patients at rest and it increased with sensory trick imagination and performance. SMA-right cerebellum connectivity also increased with sensory trick imagination in CD patients, while it decreased in healthy controls. In CD patients, SMA connectivity increased in the brain regions involved in sensorimotor integration during sensory trick performance and imagination. Our study results showed a crucial role of SMA in sensorimotor processing during sensory trick performance and imagination and suggest the IPS as a novel potential therapeutic target for brain modulation.

Gray Matter Structural and Functional Alterations in Idiopathic Blepharospasm: A Multimodal Meta-Analysis of VBM and Functional Neuroimaging Studies

Background

Neuroimaging studies have shown gray matter structural and functional alterations in patients with idiopathic blepharospasm (iBSP) but with variations. Here we aimed to investigate the specific and common neurostructural/functional abnormalities in patients with iBSP.

Methods

A systematic literature search from PubMed, Web of Science and Embase was conducted to identify relevant publications. We conducted separate meta-analysis for whole-brain voxel-based morphometry (VBM) studies and for functional imaging studies, and a multimodal meta-analysis across VBM and functional studies in iBSP, using anisotropic effect size-based signed differential mapping.

Results

The structural database comprised 129 patients with iBSP and 144 healthy controls whilst the functional database included 183 patients with iBSP and 253 healthy controls. The meta-analysis of VBM studies showed increased gray matter in bilateral precentral and postcentral gyri, right supplementary motor area and bilateral paracentral lobules, while decreased gray matter in right superior and inferior parietal gyri, left inferior parietal gyrus, left inferior temporal gyrus, left fusiform gyrus and parahippocampal gyrus. The meta-analysis of functional studies revealed hyperactivity in right dorsolateral superior frontal gyrus, left thalamus and right fusiform gyrus, while hypoactivity in left temporal pole, left insula, left precentral gyrus, bilateral precuneus and paracentral lobules, right supplementary motor area and middle frontal gyrus. The multimodal meta-analysis identified conjoint anatomic and functional changes in left precentral gyrus, bilateral supplementary motor areas and paracentral lobules, right inferior occipital gyrus and fusiform gyrus.

Conclusions

The patterns of conjoint and dissociated gray matter alterations identified in the meta-analysis may enhance our understanding of the pathophysiological mechanisms underlying iBSP.

Oromandibular dystonia – A systematic review

Oromandibular dystonia (OMD) is a clinical problem which is commonly encountered in the practice of movement disorders. OMD results from a variety of genetic and acquired etiologies and can occur as an isolated manifestation, or as part of an isolated generalized or a combined dystonia syndrome. There are only very few systematic reviews on this condition which often causes significant disability. We review here the etiology, clinical features, diagnostic approach and management of OMD.

Oromandibular dystonia and temporomandibular disorders

BACKGROUND

The aim of this study was to characterize clinical features of patients with oromandibular dystonia (OMD) who had temporomandibular disorder (TMD) symptoms.

METHODS

A retrospective chart review of patients seeking treatment at a tertiary-level orofacial pain clinic from January 2015 through December 2020 was undertaken. The inclusionary criteria consisted of a diagnosis of OMD (International Classification of Diseases, Revision 10 code G24.4), which had been confirmed by a neurologist.

RESULTS

Eleven patients met the inclusion criteria. Focal dystonia and jaw deviation OMD were the most frequent diagnoses. A dental procedure was a triggering or aggravating factor in 36.4% of patients. All but 2 patients had a sensory trick, or tactile stimulus to a particular body part, and approximately one-half of the patients used an oral appliance as a sensory trick device. All but 1 patient had received a diagnosis of TMD, with myofascial pain of the masticatory muscles being the most prevalent diagnosis. Four patients had received a recommendation for orthodontic treatment. About one-half of the patients had undergone 1 or more invasive dental or maxillofacial surgical interventions to address their dystonia. Anxiety was the most common psychological comorbidity.

CONCLUSIONS

Because patients with OMD commonly experience TMD symptoms, they can receive a misdiagnosis of TMD while the OMD is overlooked.

PRACTICAL IMPLICATIONS

Owing to concomitant TMD symptoms, patients most often seek dental consultations and undergo treatments such as orthodontic interventions and temporomandibular joint surgeries. A dentist's competency in recognizing these patients can prevent unnecessary procedures and facilitate appropriate patient care.

Comparing Brain Functional Activities in Patients With Blepharospasm and Dry Eye Disease Measured With Resting-State fMRI

Background: Blepharospasm (BSP) and dry eye disease (DED) are clinically common diseases characterized by an increased blinking rate. A sustained eyelid muscle activity may alter the cortical sensorimotor concordance and lead to secondary functional changes. This study aimed to explore the central mechanism of BSP by assessing brain functional differences between the two groups and comparing them with healthy controls.

Methods: In this study, 25 patients with BSP, 22 patients with DED, and 23 healthy controls underwent resting-state functional magnetic resonance imaging (fMRI) scan. The amplitude of low-frequency fluctuations (ALFF) was applied to analyze the imaging data.

Results: Analysis of covariance (ANCOVA) revealed widespread differences in ALFF across the three groups. In comparison with healthy controls, patients with BSP showed abnormal ALFF in the sensorimotor integration related-brain regions, including the bilateral supplementary motor area (SMA), left cerebellar Crus I, left fusiform gyrus, bilateral superior medial prefrontal cortex (MPFC), and right superior frontal gyrus (SFG). In comparison with patients with DED, patients with BSP exhibited a significantly increased ALFF in the left cerebellar Crus I and left SMA. ALFF in the left fusiform gyrus/cerebellar Crus I was positively correlated with symptomatic severity of BSP.

Conclusions: Our results reveal that the distinctive changes in the brain function in patients with BSP are different from those in patients with DED and healthy controls. The results further emphasize the primary role of sensorimotor integration in the pathophysiology of BSP.

Sensory tricks modulate corticocortical and corticomuscular connectivity in cervical dystonia

OBJECTIVE

To examine interactions between cortical areas and between cortical areas and muscles during sensory tricks in cervical dystonia (CD).

METHODS

Thirteen CD patients and thirteen age-matched healthy controls performed forewarned reaction time tasks, sensory tricks, and two tasks replicating aspects of the tricks (moving necks/arms). Control subjects mimicked sensory tricks. Corticocortical and corticomuscular coherence values were calculated from surface electrodes placed over motor, premotor, and sensory cortical areas and dystonic muscles.

RESULTS

During initial preparation (after the warning stimulus), the only between-task difference was found in the γ-band corticocortical coherence (higher during tricks than during voluntary neck movements). With movements (before/after the imperative stimulus), the γ-band coherence of CD patients significantly increased during tricks but decreased during voluntary movements, while opposite trends were observed in healthy subjects. Additionally, the α- and β-band coherence decreased in healthy subjects during movements. Between the two patient subgroups (typical vs. forcible tricks), only those with typical tricks showed significant decrease in corticomuscular coherence during tricks.

CONCLUSIONS

Observed changes in the corticocortical coherence suggest that sensory tricks improve cortical function, which reduces corticomuscular connectivity and the dystonia.

SIGNIFICANCE

We demonstrated that sensory tricks fundamentally affect sensorimotor integration in CD, both in movement preparation and execution.

Diagnostic criteria for blepharospasm: A multicenter international study

BACKGROUND

There are no widely accepted criteria to aid the physician in diagnosing BSP.

OBJECTIVE

To validate recently proposed diagnostic criteria for blepharospasm in a larger and geographically diverse population and to develop a screening system for blepharospasm.

METHODS

Video-recordings from 211 blepharospasm patients and 166 healthy/disease controls were examined by 8 raters. Agreement for presence of orbicularis oculi spasms, sensory trick, and increased blinking was measured by k statistics. Inability to voluntarily suppress the spasms was asked by the examiner but not captured in the video. Patients/controls were also requested to fill a self-administered questionnaire addressing relevant blepharospasm clinical aspects. The diagnosis at each site was the gold standard for sensitivity/specificity.

RESULTS

All the study items yielded satisfactory inter/intra-observer agreement. Combination of items rather than each item alone reached satisfactory sensitivity/specificity. The combined algorithm started with recognition of spasms followed by sensory trick. In the absence of a sensory trick, including "increased blinking" or "inability to voluntarily suppress the spasms" or both items yielded 88-92% sensitivity and 79-83% specificity. No single question of the questionnaire yielded high sensitivity/specificity. Serial application of the questionnaire to our blepharospasm and control subjects and subsequent clinical examination of subjects screening positive by the validated diagnostic algorithms yielded 78-81% sensitivity and 83-91% specificity.

CONCLUSION

These results support the use of proposed diagnostic criteria in multi-ethnic, multi-center cohorts. We also propose a case-finding procedure to screen blepharospasm in a given population with less effort than would be required by examination of all subjects.

Sensory trick effect in craniofacial dystonia as one of the possible impacts of wearing face masks during the COVID-19 pandemic

BACKGROUND

The report of a patient with blepharospasm during the COVID-19 pandemic suggested a potential ameliorating effect of wearing a face mask.

OBJECTIVE

We prospectively evaluated a possible symptom change through wearing a face mask in all consecutive patients with craniofacial hyperkinesias in our botulinum toxin outpatient treatment cohort.

METHODS

Patients with craniofacial hyperkinesia were asked to rate changes of symptoms between - 2 (markedly worsened), - 1 (slightly worsened), 0 (no change), + 1 (slightly improved) and + 2 (markedly improved).

RESULTS

Of 101 patients (19 with blepharospasm [BSP], 54 with cervical dystonia [CD], 6 with oromandibular dystonia [OMD], and 22 with hemifacial spasm [HFS]) 81 (80%) rated no symptom change, 11 (11%) symptom improvement, and 9 (9%) symptom worsening. Improvements in 9 of the 82 dystonia patients (BSP, CD, OMD) consisted of a perceived decrease in dystonic activity. 33% of dystonia patients had previously noticed or used a sensory trick. Its presence turned out to be a significant predictor of improvement during mask wearing. Deteriorations were attributed from all patients to disturbing effects of the mask interacting with facial muscle overactivity. Improvements in HSF patients were attributed to the symptom-hiding nature of the mask and not to an effect on the spasm activity itself.

CONCLUSIONS

Wearing a face mask did not affect self-perceived symptoms in 80% of patients with craniofacial hyperkinesis. 11% of patients reported an improvement, which occurred as sensory trick in dystonia patients and as a concealment of a stigmatizing facial expression in patients with HSF.

Defective Somatosensory Inhibition and Plasticity Are Not Required to Develop Dystonia

BACKGROUND

Dystonia may have different neuroanatomical substrates and pathophysiology. This is supported by studies on the motor system showing, for instance, that plasticity is abnormal in idiopathic dystonia, but not in dystonia secondary to basal ganglia lesions.

OBJECTIVE

The aim of this study was to test whether somatosensory inhibition and plasticity abnormalities reported in patients with idiopathic dystonia also occur in patients with dystonia caused by basal ganglia damage.

METHODS

Ten patients with acquired dystonia as a result of basal ganglia lesions and 12 healthy control subjects were recruited. They underwent electrophysiological testing at baseline and after a single 45-minute session of high-frequency repetitive somatosensory stimulation. Electrophysiological testing consisted of somatosensory temporal discrimination, somatosensory-evoked potentials (including measurement of early and late high-frequency oscillations and the spatial inhibition ratio of N20/25 and P14 components), the recovery cycle of paired-pulse somatosensory-evoked potentials, and primary motor cortex short-interval intracortical inhibition.

RESULTS

Unlike previous reports of patients with idiopathic dystonia, patients with acquired dystonia did not differ from healthy control subjects in any of the electrophysiological measures either before or after high-frequency repetitive somatosensory stimulation, except for short-interval intracortical inhibition, which was reduced at baseline in patients compared to control subjects.

CONCLUSIONS

The data show that reduced somatosensory inhibition and enhanced cortical plasticity are not required for the clinical expression of dystonia, and that the abnormalities reported in idiopathic dystonia are not necessarily linked to basal ganglia damage. © 2020 International Parkinson and Movement Disorder Society.

Effect of Neck Botulinum Neurotoxin Injection on Proprioception and Somatosensory-Motor Cortical Processing in Cervical Dystonia

Background. Cervical dystonia (CD) is a neurological movement disorder characterized by involuntary contractions of the cervical musculature and is known to be associated with proprioceptive dysfunction in dystonic/nondystonic limbs. Objectives. We examined how neck botulinum neurotoxin (BoNT) injection affects wrist proprioception and the corresponding sensorimotor cortical activity in CD. Method. Wrist position sense acuity of the dominant (right) hand was evaluated in 15 CD and 15 control participants. Acuity measures were a psychophysical position sense discrimination threshold (DT; based on passive joint displacement) and joint position matching error (based on active movement). Cortical activity during the motor preparation period of the active joint position matching was examined using electroencephalography. Results. In their symptomatic state, patients demonstrated a significantly higher wrist proprioceptive DT, indicating an abnormal passive wrist position sense. Yet BoNT injections had no significant effect on this threshold. During active joint position matching, errors were significantly larger in patients, but this difference vanished after the administration of BoNT. Motor preparation of active wrist position matching was associated with a significantly higher rise of β-band (13-30 Hz) power over contralateral somatosensory-motor cortical areas in patients. This excessive cortical activity significantly declined post-BoNT. Conclusion. Wrist proprioceptive perception during passive/active movements is abnormal in CD. An excessive rise of premotor/motor cortical β-oscillations during motor planning is associated with this proprioceptive dysfunction. Neck BoNT injections normalized the cortical processing of proprioceptive information from nonsymptomatic limbs, indicating that local injections may affect the central mechanisms of proprioceptive function in CD.

Cause or effect: Altered brain and network activity in cervical dystonia is partially normalized by botulinum toxin treatment

Background

Idiopathic cervical dystonia (CD) is a chronic movement disorder characterized by impressive clinical symptoms and the lack of clear pathological findings in clinical diagnostics and imaging. At present, the injection of botulinum toxin (BNT) in dystonic muscles is an effective therapy to control motor symptoms and pain in CD.

Objectives

We hypothesized that, although it is locally injected to dystonic muscles, BNT application leads to changes in brain and network activity towards normal brain function.

Methods

Using 3 T functional MR imaging along with advanced analysis techniques (functional connectivity, Granger causality, and regional homogeneity), we aimed to characterize brain activity in CD (17 CD patients vs. 17 controls) and to uncover the effects of BNT treatment (at 6 months).

Results

In CD, we observed an increased information flow within the basal ganglia, the thalamus, and the sensorimotor cortex. In parallel, some of these structures became less responsive to regulating inputs. Furthermore, our results suggested an altered somatosensory integration. Following BNT administration, we noted a shift towards normal brain function in the CD patients, especially within the motor cortex, the somatosensory cortex, and the basal ganglia.

Conclusion

The changes in brain function and network activity in CD can be interpreted as related to the underlying cause, the effort to compensate or a mixture of both. Although BNT is applied in the last stage of the cortico-neuromuscular pathway, brain patterns are shifted towards those of healthy controls.

•

we characterized brain activity in CD and the effects of BNT using 3T fMR imaging and network analysis techniques

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following treatment with botulinum toxin (BNT), abnormal brain activity patterns in primary dystonia are attenuated

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critical key regions for both the pathophysiology and BNT-induced improvement in cervical dystonia are the BG

Sensory Trick Frames: A New Device for Blepharospasm Patients

Objective

To determine whether the use of unique customized spectacles provided with modified side arms may be helpful in reducing benign essential blepharospasm (BEB) in patients describing periocular sensory tricks (ST).

Methods

A prospective descriptive study of patients with BEB with positive periocular or temporal region ST phenomenon response under the care of the Botox Clinic at Moorfields Eye Hospital, London, UK. Nine consecutive patients with BEB describing ST were recruited, and the disease frequency and severity were assessed with the Jankovic Rating Scale (JRS) and the Blepharospasm Disability Index (BSDI) before and after the use of the sensory trick frames (STF).

Results

A reduction in the score was noted in both severity (p = 0.0115) and frequency patterns (p = 0.0117) in the JRS in patients using the STF. A significant reduction of the BSDI score was also observed (p = 0.0314).

Conclusion

All the patients selected and fitted with the STF had a reduction in spasms and related symptoms. This new device may be helpful in some selected BEB patients who previously responded positively to periocular pressure alleviating maneuvers.

Sensory trick in upper limb dystonia

INTRODUCTION

Sensory trick is a specific maneuver that temporarily improves dystonia that is usually observed in 44%-89% of patients with cranial-cervical dystonia and in 20% of patients with upper limb dystonia. This study aimed to assess the prevalence of sensory trick in a cohort of 37 patients with idiopathic adult-onset upper limb dystonia and to determine whether sensory trick can be a useful tool to distinguish dystonic and non-dystonic tremor.

METHODS

Thirty-seven right-handed patients with idiopathic upper limb dystonia and disturbed handwriting and 19 patients with non-dystonic action tremor in the upper limb causing writing disturbances participated into the study. Patients were asked to write a standard sentence twice, before and after applying a standardized sensory trick (gently grabbing right wrist with his left hand). Readability of the two sentences was assessed by three observers blinded to diagnosis.

RESULTS

Five/37 patients (13%) self-discovered ST over disease history, while performing the standardized trick maneuver improved handwriting in 14/37 patients (38%). Interobserver agreement on the effectiveness of sensory trick among the three observers yielded a kappa value of 0.86 (p < 0.0001). The standardized trick was effective in 8/19 patients with dystonic tremor (42%) and in 0/19 patients with non-dystonic tremor (p = 0.003).

CONCLUSION

The results of applying a standardized non-spontaneous trick demonstrated that, in upper limb dystonia, ST may be more frequent than usually observed. Effective sensory trick, when present, may be a hallmark of idiopathic dystonia. The lack of effective sensory trick may help to identify non dystonic upper limb tremor.

Sensory trick efficacy in cervical dystonia is linked to processing of neck proprioception

BACKGROUND

Muscle vibration activates muscle spindles and when applied over posterior neck muscles during stance modulates global body orientation. This is characterised by a tonic forward sway response that is reportedly diminished or absent in patients with idiopathic cervical dystonia.

OBJECTIVE

To investigating the impact of the sensory trick on vibration-induced postural responses.

METHODS

20 patients with idiopathic cervical dystonia and a sensory trick, 15 patients without a trick, and 16 healthy controls were recruited. Neck muscle vibration was applied bilaterally over the upper trapezius under three different conditions: 1) Quiet standing; 2) standing while performing the trick (or trick-like movement in non-responders); 3) standing while elevating the flexed arm without touching any part of the body. Centre of pressure position and whole-body orientation in the sagittal plane were analysed.

RESULTS

Patients with a sensory trick responded similarly to healthy controls: neck muscle vibration led to an initial forward sway of the body that slowly increased during the prolonged vibration for all three conditions. This response was mainly mediated by ankle flexion. In patients without a trick, the initial sagittal sway was significantly reduced in all three conditions and the later slow increase was absent. Performance of the trick did not have an effect on any aspect of the response in either cervical dystonia group.

CONCLUSIONS

The whole-body response to neck vibration in cervical dystonia differs depending on the effectiveness of the sensory trick to alleviate the dystonic neck posture. Variable pathophysiology of proprioceptive processing may be the common factor.

Clinical Features of Benign Essential Blepharospasm in Korean Patients

Purpose

To analyze the clinical features of benign essential blepharospasm in Korean patients.

Methods

Patients diagnosed with benign essential blepharospasm in Kim's Eye Hospital from November 2014 to December 2016 were evaluated using a clinical examination and questionnaire. The questionnaire reviewed personal medical history, demographic factors, risk factors for blepharospasm development, and relieving and aggravating factors.

Results

Of the 101 patients enrolled, 78 (77.2%) were women. The mean age was 64.9 years old. Hypertension was the most common medical disorder (42.6%), followed by diabetes mellitus. The majority of the patients were non-smokers (83.2%) and drank less than a cup of a caffeinated beverage a day (30.7%). Fifty-seven percent of patients reported no stressful events immediately prior to symptom development. Fatigue and stress were aggravating factors in more than 55% of patients; rest was the most common relieving factor (35.6%).

Conclusions

Here, we report the clinical features of benign essential blepharospasm in Korean patients for the first time. The results were consistent with previous reports showing that the majority of benign essential blepharospasm patients are women and non-smokers. In contrast to previous reports though, fatigue and stress were aggravating factors, and the most common relieving factor was rest. No stressful events had immediately preceded the development of blepharospasm in 57.4% of patients. This report may aid in treating and counseling patients with benign essential blepharospasm.

Voxel-Mirrored Homotopic Connectivity of Resting-State Functional Magnetic Resonance Imaging in Blepharospasm

Objective: Several networks in human brain are involved in the development of blepharospasm. However, the underlying mechanisms for this disease are poorly understood. A voxel-mirrored homotopic connectivity (VMHC) method was used to quantify the changes in functional connectivity between two hemispheres of the brain in patients with blepharospasm.

Methods: Twenty-four patients with blepharospasm and 24 healthy controls matched by age, sex, and education were recruited. The VMHC method was employed to analyze the fMRI data. The support vector machine (SVM) method was utilized to examine whether these abnormalities could be applied to distinguish the patients from the controls.

Results: Compared with healthy controls, patients with blepharospasm showed significantly high VMHC in the inferior temporal gyrus, interior frontal gyrus, posterior cingulate cortex, and postcentral gyrus. No significant correlation was found between abnormal VMHC values and clinical variables. SVM analysis showed a combination of increased VMHC values in two brain areas with high sensitivities and specificities (83.33 and 91.67% in the combined inferior frontal gyrus and posterior cingulate cortex; and 83.33 and 87.50% in the combined inferior temporal gyrus and postcentral gyrus).

Conclusion: Enhanced homotopic coordination in the brain regions associated with sensory integration networks and default-mode network may be underlying the pathophysiology of blepharospasm. This phenomenon may serve as potential image markers to distinguish patients with blepharospasm from healthy controls.

Treatment of Blepharospasm/Hemifacial Spasm

OPINION STATEMENT

The treatment of both hemifacial spasm (HFS) and blepharospasm (BEB) requires making the appropriate clinical diagnosis. Advance imaging and electrophysiologic studies are useful; however, one's clinical suspicion is paramount. The purpose of this review is to summarize current and emerging therapies for both entities. Botulinum toxin (BTX) remains the first-line therapy to treat both conditions. If chemodenervation has failed, surgery may be considered. Due to the risks associated with surgery, the benefits of this option must be carefully weighed. Better surgical outcomes are possible when procedures are performed at tertiary centers with experienced surgeons and advanced imaging techniques. Microvascular decompression is an efficacious method to treat HFS, and myectomy is an option for medication-refractory BEB; the risks of the latter may outweigh any meaningful clinical benefits. Oral agents only provide short-term relief and can cause several unwanted effects; they are reserved for patients who cannot receive BTX and/or surgery. Transcranial magnetic stimulation has gained some traction in the treatment of BEB and may provide safer non-invasive options for refractory patients in the future.

Eyelid Dysfunction in Neurodegenerative, Neurogenetic, and Neurometabolic Disease

Eye movement abnormalities are among the earliest clinical manifestations of inherited and acquired neurodegenerative diseases and play an integral role in their diagnosis. Eyelid movement is neuroanatomically linked to eye movement, and thus eyelid dysfunction can also be a distinguishing feature of neurodegenerative disease and complements eye movement abnormalities in helping us to understand their pathophysiology. In this review, we summarize the various eyelid abnormalities that can occur in neurodegenerative, neurogenetic, and neurometabolic diseases. We discuss eyelid disorders, such as ptosis, eyelid retraction, abnormal spontaneous and reflexive blinking, blepharospasm, and eyelid apraxia in the context of the neuroanatomic pathways that are affected. We also review the literature regarding the prevalence of eyelid abnormalities in different neurologic diseases as well as treatment strategies (Table 1).

Blepharospasm 40 years later

Forty years ago, C.D. Marsden proposed that blepharospasm should be considered a form of adult-onset focal dystonia. In the present paper, we provide a comprehensive overview of the findings regarding blepharospasm reported in the past 40 years. Although prolonged spasms of the orbicularis oculi muscles remain the clinical hallmark of blepharospasm, patients with blepharospasm may be characterized by various types of involuntary activation of periocular muscles. In addition to motor features, blepharospasm patients may also have nonmotor manifestations, including psychiatric, mild cognitive, and sensory disturbances. The various motor and nonmotor symptoms are not present in all patients, suggesting that blepharospasm is phenomenologically a heterogeneous condition. This emphasizes the need for tools for severity assessment that take into account both motor and nonmotor manifestations. The cause of blepharospasm remains elusive, but several lines of evidence indicate that blepharospasm is a multifactorial condition in which one, or several, as yet unknown genes together with epigenetic and environmental factors combine to reach the threshold of the disease. Although blepharospasm was originally believed to be solely a basal ganglia disorder, neurophysiological and neuroimaging evidence point to anatomical and functional involvement of several brain regions. The contribution of multiple areas has led to the hypothesis that blepharospasm should be considered as a network disorder, and this might reflect the varying occurrence of motor and nonmotor manifestations in blepharospasm patients. Despite advances in the aetiology and pathophysiology, treatment remains symptomatic. © 2017 International Parkinson and Movement Disorder Society.

Dynamic head-neck stabilization in cervical dystonia

BACKGROUND

Effective sensorimotor integration is essential to modulate (adapt) neck stabilization strategies in response to varying tasks and disturbances. This study evaluates the hypothesis that relative to healthy controls cervical dystonia patients have an impaired ability to modulate afferent feedback for neck stabilization with changes in the frequency content of mechanical perturbations.

METHODS

We applied anterior-posterior displacement perturbations (110s) on the torso of seated subjects, while recording head-neck kinematics and muscular activity. We compared low bandwidth (0.2-1.2Hz) and high bandwidth (0.2-8Hz) perturbations where our previous research showed a profound modulation of stabilization strategies in healthy subjects. Cervical dystonia patients and age matched controls performed two tasks: (1) maintain head forward posture and (2) allow dystonia to dictate head posture.

FINDINGS

Patients and controls demonstrated similar kinematic and muscular responses. Patient modulation was similar to that of healthy controls (P>0.05); neck stiffness and afferent feedback decreased with high bandwidth perturbations. During the head forward task patients had an increased neck stiffness relative to controls (P<0.05), due to increased afferent feedback.

INTERPRETATION

The unaffected modulation of head-neck stabilization (both kinematic and muscular) in patients with cervical dystonia does not support the hypothesis of impaired afferent feedback modulation for neck stabilization.

What is new in tics, dystonia and chorea?

Movement disorders comprise hyperkinetic involuntary movements (eg tremor, myoclonus, tics, dystonia and chorea) and hypokinetic (parkinsonism) disorders. Tics are cardinal features of primary tic disorders encompassing Tourette syndrome (TS), but are also found in some neurodegenerative conditions and may be induced by psychoactive substances. The first line treatment for tics is pharmacological (mainly dopamine receptor blockers or alpha-2 adrenergic agonists) and behavioural. Dystonia and chorea syndromes are considerably heterogeneous in aetiology, and age at onset, body distribution of the movement disorder, accompanying neurological motor and non-motor features, and systemic manifestations are all important to reach a correct aetiological diagnosis. While symptomatic pharmacological treatment remains the mainstay of treatment for choreas, deep brain stimulation surgery has a well-defined place in the management of medically refractory dystonia.

Blepharospasm: Update on Epidemiology, Clinical Aspects, and Pathophysiology

Blepharospasm (BSP) is a rather distressing form of focal dystonia. Although many aspects of its pathophysiological mechanisms are already known, we lack fundamental evidence on etiology, prevention, and treatment. To advance in our knowledge, we need to review what is already known in various aspects of the disorder and use these bases to find future lines of interest. Some of the signs observed in BSP are cause, while others are consequence of the disorder. Non-motor symptoms and signs may be a cue for understanding better the disease. Various cerebral sites have been shown to be functionally abnormal in BSP, including the basal ganglia, the cortex, and the cerebellum. However, we still do not know if the dysfunction or structural change affecting these brain regions is cause or consequence of BSP. Further advances in neurophysiology and neuroimaging may eventually clarify the pathophysiological mechanisms implicated. In this manuscript, we aim to update what is known regarding epidemiology, clinical aspects, and pathophysiology of the disorder and speculate on the directions of research worth pursuing in the near future.

The clinical phenomenology and associations of trick maneuvers in cervical dystonia

Sensory trick is an unusual clinical feature in cervical dystonia that attenuates disease symptoms by slight touch to a specific area of the face or head. Using a semi-quantitative questionnaire-based study of 197 patients with idiopathic cervical dystonia, we sought to determine probable pathophysiologic correlates, with the wider aim of examining its eventual clinical significance. The typical sensory trick, i.e., light touch, not necessitating the use of force leading to simple overpowering of dystonic activity, was present in 83 (42.1 %) patients. The vast majority of the patients required a specific sequence of sensorimotor inputs, including touch sensation on the face or different areas of the head, and also sensory and motor input of the hand itself. Deviations often led to a significant decrease in effectiveness and lack of expected benefit. Moreover, patients able to perform the maneuver reported compellingly higher subjective effect of botulinum toxin treatment (median 7 vs. 5 on a scale of 0-10; p < 0.0001) and lower depression score (median 10 vs. 14 on the Montgomery Åsberg Depression Rating scale; p < 0.001). Overall, the results point to marked disruption of sensorimotor networks in cervical dystonia. The mechanism of the sensory trick action may be associated with balancing the abnormal activation patterns by specific sensorimotor inputs. Its presence may be considered a positive predictive factor for responsiveness to botulinum toxin treatment.

Early Illustrations of Geste Antagoniste in Cervical and Generalized Dystonia

Background

Geste antagoniste, or sensory trick, is a voluntary maneuver that temporarily reduces the severity of dystonic postures or movements. We present a historical review of early reports and illustrations of geste antagoniste.

Results

In 1894, Brissaud described this phenomenon in Paris in patients with torticollis. He noted that a violent muscular contraction could be reversed by a minor voluntary action. He considered the improvement obtained by what he called “simple mannerisms, childish behaviour or fake pathological movements” was proof of the psychogenic origin of what he named mental torticollis. This concept was supported by photographical illustrations of the patients. The term geste antagoniste was used by Brissaud’s pupils, Meige and Feindel, in their 1902 monograph on movement disorders. Other reports and illustrations of this sign were published in Europe between 1894 and 1906. Although not mentioned explicitly, geste antagoniste was also illustrated in a case report of generalized dystonia in Oppenheim’s 1911 seminal description of dystonia musculorum deformans in Berlin.

Discussion

Brissaud-Meige’s misinterpretation of the geste antagoniste unfortunately anchored the psychogenic origin of dystonia for decades. In New York, Herz brought dystonia back into the realm of organic neurology in 1944. Thereafter, it was given prominence by other authors, notably Fahn and Marsden in the 1970–1980s. Nowadays, neurologists routinely investigate for geste antagoniste when a dystonic syndrome is suspected, because it provides a further argument in favor of dystonia. The term alleviating maneuver was proposed in 2014 to replace sensory trick or geste antagoniste. This major sign is now part of the motor phenomenology of the 2013 Movement Disorder Society’s classification of dystonia.

Clinical Analysis of Patients with Primary Blepharospasm: A Report of 100 Cases in China

PURPOSE

This study explored the clinical characteristics, diagnosis and treatments of primary blepharospasm.

METHODS

In this retrospective analysis, 100 patients with blepharospasm were enrolled. Data were collected from medical records and face-to-face interviews with patients and their families.

RESULTS

The age of onset was 56.4 ± 2.7 (range, 32-76 years). The duration between onset and accurate diagnosis was 38.7 ± 36.0 months (range, 2-120 months). Dry eyes occurred in 54% of the patients. The initial diagnostic accuracy was 10%. Dry eye syndrome, conjunctivitis/keratitis and myasthenia gravis caused the most confusion in the differential diagnosis. Regular botulinum toxin type A injections improved both eyelid spasms and subjective ocular symptoms in all patients.

CONCLUSIONS

Regular botulinum toxin type A injections improved both eyelid spasms and subjective ocular symptoms in blepharospasm patients. The differentiation of primary blepharospasm differentiation from dry eye syndrome, conjunctivitis/keratitis and myasthenia gravis must be improved.

Tricks in dystonia: ordering the complexity

Sensory tricks are various manoeuvres that can ameliorate dystonia. Common characteristics are well known, but their variety is wide, sensory stimulation is not necessarily the critical feature, and their physiology is unknown. To enumerate the various forms of sensory tricks and describe their nature, research findings and theories that may elucidate their neurophysiologic mechanism, we reviewed the literature pertaining to sensory tricks, including variants like motor tricks, imaginary tricks, forcible tricks and reverse sensory tricks. On the basis of this information, we propose a new classification of sensory tricks to include its variants. We highlight neurophysiologic evidence suggesting that sensory tricks work by decreasing abnormal facilitation. We tie this with established dystonia pathogenesis and postulate that sensory tricks decrease abnormally increased facilitation to inhibition ratios in the dystonic brain. It appears worthwhile for patients to search for possible sensory tricks.

Alleviating manoeuvres (sensory tricks) in cervical dystonia

BACKGROUND

There is limited information on the phenomenology, clinical characteristics and pathophysiology of alleviating manoeuvres (AM), also called 'sensory tricks' in cervical dystonia (CD).

METHODS

Individual data, collected from 10 sites participating in the Dystonia Coalition (http://clinicaltrials.gov/show/NCT01373424), included description of localisation and phenomenology of AM collected by systematic review of standardised video examinations. Analyses correlated demographic, neurologic, and psychiatric features of CD patients with or without effective AM.

RESULTS

Of 154 people studied, 138 (89.6%) used AM, of which 60 (43.4%) reported partial improvement, 55 (39.8%) marked improvement, and 4 (0.03%) no effect on dystonic posture. Light touch, usually to the lower face or neck, was used by >90%. The presence or location of AM did not correlate with the severity of the dystonia.

CONCLUSIONS

In this large and comprehensive study of CD, we found no clinical predictors of effective AM. Further studies of sensorimotor integration in dystonia are needed to better understand the pathophysiology of AM.

Long latency trigemino-cervical reflex in patients with cervical dystonia

Trigemino-cervical reflex (TCR) is elicited by stimulation of face using various modalities. TCR reflects the interaction between trigeminal system and cervical motoneurons. Such a specific interaction is assumed to play role in development of cervical dystonia (CD) through superior colliculus. In this study, we aimed to investigate alterations of the functional relationship between those structures in CD and in a subgroup with dystonic tremor. A total of consecutive 23 patients with primary CD (7 men, 16 women) and 16 age and sex matched control subjects (7 men, 9 women) were included in this study. TCR was obtained after percutaneous electrical stimulation (with duration of 0.5 ms) of infraorbital branch of trigeminal nerve while recording over splenius capitis and sternocleidomastoid muscles. Presence and onset latencies of TCR did not differ significantly between patients with CD and controls, and same pattern of muscle activation occurred in both groups. Responses of patient group seemed to have higher amplitudes and to be more persistent. There were no significant side-to-side differences of TCR probability, latency, amplitude or duration with respect to the side of head deviation in CD. Increased amplitudes and durations of responses probably reflect increased excitability of the reflex circuit. We suggest that similar latencies and response pattern in comparison to healthy individuals decrease the possibility of structural disturbance. TCR is probably under bilateral basal ganglia and dopaminergic control. Alterations of trigemino-cervical pathway are more extensive and are not solely due to local changes of brainstem interneurons.

Characteristic "Forcible" Geste Antagoniste in Oromandibular Dystonia Resulting From Pantothenate Kinase-Associated Neurodegeneration

Geste antagonistes are usually considered typical of primary dystonia, although rarely they have been described in secondary/heredodegenerative dystonias. We have recently come across a particular geste antagoniste in 5 of 10 patients with pantothenate kinase-associated neurodegeneration (PKAN) who had prominent oromandibular involvement with severe jaw-opening dystonia. It consists of touching the chin with both hands characteristically clenched into a fist with flexion at the elbows. Because of the resemblance of this geste antagoniste with the praying-like posture of Mantis religiosa, we coined the term "mantis sign." Reviewing videos of PKAN cases in literature, including what is considered the first cinematic depiction of a case of this disorder, 3 additional cases with akin maneuvers were identified. In contrast, examining 205 videos of non-PKAN dystonic patients from our database for the presence of a similar maneuver was unrevealing. Thus, we consider the mantis sign to be quite typical of PKAN and propose it to be added as a clinical hint toward diagnosis.

The definition of dystonia: current concepts and controversies

The definition of dystonia has been a subject of much debate and controversy for the last century. In this paper, a practical definition of dystonia for the movement disorders expert is presented, based on a new algorithm. © 2013 Movement Disorder Society.