Therapeutic Benefit of Sensory Trick in Cervical Dystonia

Background

Sensory tricks (STs) are voluntary maneuvers that dampen the abnormal movement in cervical dystonia (CD).

Objectives

To investigate the effect of ST on CD severity and treatment.

Methods

Data on 1039 individuals with a modified Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) score were extracted from the CD Patient Registry for Observation of OnabotulinumtoxinA (onabotA) Efficacy study. Univariate and multivariate models evaluated the direct and indirect impact of ST on CD severity and treatment, while controlling for confounds.

Results

Complete ST was associated with a 10% lower mean onabotA dose. Absence of complete ST was associated with a higher onabotA dose after controlling for dystonia severity (OR = 1.37, P = 0.04). ST moderated the relationship between dystonia severity and toxin dose (β = -0.16, P = 0.02).

Conclusions

ST is related to lower CD severity and toxin dose. It may have a direct effect on lowering toxin dose, independent of CD severity.

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.

Electrically Induced Sensory Trick in a Patient with Musician's Dystonia: A Case Report

A sensory trick is a specific maneuver that temporarily improves focal dystonia. We describe a case of musician's dystonia in the right-hand fingers of a patient, who showed good and immediate improvement after using an electrical stimulation-mimicking sensory trick. A 49-year-old professional guitarist presented with chronic involuntary flexion of the right-hand third and fourth fingers that occurred during guitar performances. Electrical stimulation with a frequency of 40 Hz and an intensity of 1.5 times the sensory threshold was administered on the third and fourth fingernails of the right hand, which facilitated fluent guitar playing. While he played guitar with and without electrical stimulation, we measured the surface electromyograms (sEMG) of the right extensor digitorum and flexor digitorum superficialis muscles to evaluate the sensory-trick-like effects of electrical stimulation. This phenomenon can offer clues for developing electrical stimulation-based treatment devices for focal dystonia. Electrical stimulation has the advantage that it can be turned off to avoid habituation. Moreover, the device is easy to use and portable. These findings warrant further investigation into the use of sensory stimulation for treating focal dystonia.

Clinical and Demographic Characteristics of Upper Limb Dystonia

BACKGROUND

Knowledge of characteristics in upper limb dystonia remains limited, derived primarily from small, single-site studies.

OBJECTIVE

The objective of this study was to characterize demographic and clinical characteristics of upper limb dystonia from the Dystonia Coalition data set, a large, international, multicenter resource.

METHODS

We evaluated clinical and demographic characteristics of 367 participants with upper limb dystonia from onset, comparing across subcategories of focal (with and without dystonia spread) versus nonfocal onset.

RESULTS

Focal onset occurred in 80%; 67% remained focal without spread. Task specificity was most frequent in this subgroup, most often writer's cramp and affecting the dominant limb (83%). Focal onset with spread was more frequent in young onset (<21 years). Focal onset occurred equally in women and men; nonfocal onset affected women disproportionately.

CONCLUSIONS

Upper limb dystonia distribution, focality, and task specificity relate to onset age and likelihood of regional spread. Observations may inform clinical counseling and design, execution, and interpretation of future studies. © 2020 International Parkinson and Movement Disorder Society.

Motor and Sensory Features of Cervical Dystonia Subtypes: Data From the Italian Dystonia Registry

Introduction: Cervical dystonia (CD) is one of the most common forms of adult-onset isolated dystonia. Recently, CD has been classified according to the site of onset and spread, in different clinical subgroups, that may represent different clinical entities or pathophysiologic subtypes. In order to support this hypothesis, in this study we have evaluated whether different subgroups of CD, that clinically differ for site of onset and spread, also imply different sensorimotor features.

Methods: Clinical and demographic data from 842 patients with CD from the Italian Dystonia Registry were examined. Motor features (head tremor and tremor elsewhere) and sensory features (sensory trick and neck pain) were investigated. We analyzed possible associations between motor and sensory features in CD subgroups [focal neck onset, no spread (FNO-NS); focal neck onset, segmental spread (FNO-SS); focal onset elsewhere with segmental spread to neck (FOE-SS); segmental neck involvement without spread (SNI)].

Results: In FNO-NS, FOE-SS, and SNI subgroups, head tremor was associated with the presence of tremor elsewhere. Sensory trick was associated with pain in patients with FNO-NS and with head tremor in patients with FNO-SS.

Conclusion: The frequent association between head tremor and tremor elsewhere may suggest a common pathophysiological mechanism. Two mechanisms may be hypothesized for sensory trick: a gating mechanism attempting to reduce pain and a sensorimotor mechanism attempting to control tremor.

Refractory Open Jaw Oromandibular Tardive Dystonia with a Sensory Trick, Treated with Botulinum Toxin: A Case Report

Jaw-opening oromandibular dystonia (O-OMD) is a clinical subtype of OMD, commonly resistant to treatment. Here, we report a distinct case of tardive O-OMD with a characteristic sensory trick, successfully treated with high-dose botulinum toxin (BTX) injection. A 34-year-old male patient presented with involuntary jaw opening, tongue protrusion, dysarthria, and mild cervical dystonia. The patient reported improved abilities to talk and close his mouth after putting something, like a cigarette, between his teeth. After an unsuccessful treatment with anticholinergic medications, the patient received electromyography-guided BTX injection to the lateral pterygoids (through an extraoral approach), sternocleidomastoids, trapezius, tongue, and platysma muscles. Following the injection, the patient reported marked improvements in his ability to talk and close his mouth without using his sensory trick. One month later, we detected a 58.2% improvement in the Abnormal Involuntary Movement Scale score. Therefore, high-dose BTX injection may be an effective alternative in refractory O-OMD.

Sensory Trick in a Patient with Cervical Dystonia: Insights from Magnetoencephalography

BACKGROUND

The proposed mechanisms for the sensory trick include peripheral sensory feedback to aid in correcting abnormal posture or movement.

CASE REPORT

A 53-year-old woman with cervical dystonia underwent magnetoencephalography pre- and post-botulinum toxin injection and sensory trick, which was described as yawning. Study revealed connectivity between the left frontal and inferior frontal gyrus before yawning, which changed to the visual cortex and right middle frontal gyrus with yawning. Beta frequencies reduced and gamma frequencies increased after yawning.

DISCUSSION

The increase in gamma frequency bands may indicate increased GABAergic activity. Increase in connectivity in the right cerebellar region underscores the importance of cerebellum in pathogenesis of dystonia.

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.

Sensory trick phenomenon improves motor control in pianists with dystonia: prognostic value of glove-effect

Musician’s dystonia (MD) is a task-specific movement disorder that causes loss of voluntary motor control while playing the instrument. A subgroup of patients displays the so-called sensory trick: alteration of somatosensory input, e.g., by wearing a latex glove, may result in short-term improvement of motor control. In this study, the glove-effect in pianists with MD was quantified and its potential association with MD-severity and outcome after treatment was investigated. Thirty affected pianists were included in the study. Music instrument digital interface-based scale analysis was used for assessment of fine motor control. Therapeutic options included botulinum toxin, pedagogical retraining and anticholinergic medication (trihexyphenidyl). 19% of patients showed significant improvement of fine motor control through wearing a glove. After treatment, outcome was significantly better in patients with a significant pre-treatment sensory trick. We conclude that the sensory trick may have a prognostic value for the outcome after treatment in pianists with MD.

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.

Clinical, Etiological, and Therapeutic Features of Jaw-opening and Jaw-closing Oromandibular Dystonias: A Decade of Experience at a Single Treatment Center

BACKGROUND

Dystonia is a heterogeneous hyperkinetic disorder. The anatomical location of the dystonia helps clinicians guide their evaluation and treatment plan. When dystonia involves masticatory, lingual, and pharyngeal muscles, it is referred to as oromandibular dystonia (OMD).

METHODS

We identified patients diagnosed with OMD in a Movement Disorders Clinic and Laryngeal Movement Disorders Clinic from a single institution. Demographic, etiological, clinical, and therapeutic information was retrospectively reviewed for patients with jaw-opening (O-OMD) and jaw-closing (C-OMD) OMD.

RESULTS

Twenty-seven patients were included. Their average age of onset was in the sixth decade of life and there was a female predominance. Etiological factors linked in this study to OMD included a family history of dystonia or essential tremor, occupation, cerebellar disease, a dental disorder, and tardive syndrome. Clinically, patients with C-OMD presented with more prominent feeding difficulties, but seemed to respond better to therapy than those with O-OMD. In addition to the known benefits of botulinum toxin therapy, patients who described sensory tricks obtained benefit from the use of customized dental prosthesis.

DISCUSSION

This works provides useful information on potential etiological factors for OMD and its response to therapy, and highlights the potential benefit of dental prosthesis for the treatment of OMD.

Altered sensory feedbacks in pianist's dystonia: the altered auditory feedback paradigm and the glove effect

Background: This study investigates the effect of altered auditory feedback (AAF) in musician's dystonia (MD) and discusses whether AAF can be considered as a sensory trick in MD. Furthermore, the effect of AAF is compared with altered tactile feedback, which can serve as a sensory trick in several other forms of focal dystonia.

Methods: The method is based on scale analysis (Jabusch et al., 2004). Experiment 1 employs synchronization paradigm: 12 MD patients and 25 healthy pianists had to repeatedly play C-major scales in synchrony with a metronome on a MIDI-piano with three auditory feedback conditions: (1) normal feedback; (2) no feedback; (3) constant delayed feedback. Experiment 2 employs synchronization-continuation paradigm: 12 MD patients and 12 healthy pianists had to repeatedly play C-major scales in two phases: first in synchrony with a metronome, secondly continue the established tempo without the metronome. There are four experimental conditions, among them three are the same AAF as in Experiment 1 and 1 is related to altered tactile sensory input. The coefficient of variation of inter-onset intervals of the key depressions was calculated to evaluate fine motor control.

Results: In both experiments, the healthy controls and the patients behaved very similarly. There is no difference in the regularity of playing between the two groups under any condition, and neither did AAF nor did altered tactile feedback have a beneficial effect on patients' fine motor control.

Conclusions: The results of the two experiments suggest that in the context of our experimental designs, AAF and altered tactile feedback play a minor role in motor coordination in patients with musicians' dystonia. We propose that altered auditory and tactile feedback do not serve as effective sensory tricks and may not temporarily reduce the symptoms of patients suffering from MD in this experimental context.

A novel presentation of an ocular geste antagoniste in cervical dystonia: a case report

BACKGROUND

A geste antagoniste or sensory trick is a well described phenomenon associated with primary cervical dystonia. Craniocervical tactile stimulation or stereotyped limb movements allow patients to transiently ameliorate dystonic activation of cervical musculature.

CASE REPORT

We report a patient with primary cervical dystonia who presented with a novel "ocular" geste antagoniste. Through a sensory trick of tonic left eye deviation, the patient transiently reduces cervical dystonic activity (improved range of motion and reduced dystonic tremor). Multi-channel surface electromyography and video are used to illustrate these findings.

DISCUSSION

This case presents a unique clinical observation of specific voluntary eye movements attenuating cervical dystonia. The phenomenon is phenotypically consistent with previously described limb sensorimotor tricks.