Cervical dystonia pathophysiology and treatment options

Botulinum Toxin Utilization, Treatment Patterns, and Healthcare Costs Among Patients with Spasticity or Cervical Dystonia in the US

INTRODUCTION

Spasticity and cervical dystonia (CD) are movement disorders with considerable direct and indirect healthcare cost implications. Although several studies have discussed their clinical impact, few have calculated the economic burden of these disorders. This study aimed to understand treatment/injection patterns of botulinum toxins type A (BoNT-As) and the characteristics, healthcare resource utilization (HCRU), and costs among patients with spasticity or CD.

METHODS

Retrospective analyses were conducted using administrative healthcare claims from the IQVIA PharMetrics® Plus database, from October 1, 2015 to December 31, 2019. Eligible patients were selected based on Healthcare Common Procedure Coding System codes for BoNT-A (index date) and ICD-10 diagnosis codes for spasticity or CD with 6 months of continuous enrollment pre-index and 12 months post-index. Patients were stratified into adult spasticity, pediatric spasticity, and CD cohorts, and were evaluated for injection patterns, HCRU, and costs in the post-index period.

RESULTS

Overall, 2452 adults with spasticity, 1364 pediatric patients with spasticity, and 1529 adults with CD were included. Total mean all-cause healthcare costs were US$42,562 (adult spasticity), $54,167 (pediatric spasticity), and $25,318 (CD). Differences were observed in the cost of BoNT-A injection visits between toxins, with abobotulinumtoxinA (aboBoNT-A) having the lowest injection cost across all indications.

CONCLUSIONS

AboBoNT-A had the lowest injection visit costs across indications. These results are suggestive of real-world resource utilization patterns and costs, and, while helpful in informing insurers' BoNT-A management strategies, further research into cost differences is warranted.

Selective denervation for cervical dystonia

Cervical dystonia (spasmodic torticollis) is a condition that involves sustained, involuntary contraction of neck and shoulder muscles, leading to abnormal movements and head posture. The authors present the case of a 41-year-old man with severe right rotational torticollis for 1.5 years due to predominant right cervical paraspinal and left sternocleidomastoid muscle hyperactivity. Following failed medical management, the patient elected to undergo surgical treatment for his torticollis. In their video, the authors discuss the steps of selective denervation using a modified Bertrand procedure, highlighting the associated anatomy and surgical planes. At the 1.5-year follow-up, the patient had no pain and his head position remained straight. The video can be found here: https://stream.cadmore.media/r10.3171/2022.9.FOCVID2291.

Evaluation of outcome of different neurosurgical modalities in management of cervical dystonia

Background

Cervical dystonia is the most common form of focal dystonia and is managed by multiple modalities including repeated botulinum toxin injections, in addition to medical treatment with anticholinergics, muscle relaxants, and physiotherapy. However, surgical interventions could be beneficial in otherwise refractory patients. This study aims to report our experience in the neurosurgical management of cervical dystonia and evaluate patient outcomes using reliable outcome scores for the assessment of patients with cervical dystonia and possible complications. This case series study was conducted on 19 patients with cervical dystonia of different etiologies who underwent surgical management [ten patients underwent selective peripheral denervation, five patients underwent pallidotomy, and four patients underwent bilateral globus pallidus internus (GPi) deep brain stimulation (DBS)] in the period between July 2018 and June 2021 at Ain Shams University Hospitals, Cairo, Egypt. With the assessment of surgical outcomes using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and the Tsui scale 6 months postoperatively.

Results

Surgical management of patients with cervical dystonia of either primary or secondary etiology was associated with significant improvement in head and neck postures after 6 months without major complications associated with the different surgical procedures. The mean improvement in total TWSTRS and Tsui scores were 51.2% and 64.8%, respectively, compared with preoperative scores, while the mean improvement in the TWSTRS subscales (severity, disability, and pain) were 40.2%, 66.9%, and 58.3%, respectively.

Conclusion

Cervical dystonia patients in whom non-surgical options have failed to alleviate their symptoms can be managed surgically leading to significant improvements with minimal adverse effects. However, surgical treatment should be tailored according to several factors including but not limited to the etiology, pattern of dystonic activity, and comorbidities. Therefore, management should be tailored to achieve long-term improvement with minimal risk of complications.

Phase-Dependent Deep Brain Stimulation: A Review

Neural oscillations are repetitive patterns of neural activity in the central nervous systems. Oscillations of the neurons in different frequency bands are evident in electroencephalograms and local field potential measurements. These oscillations are understood to be one of the key mechanisms for carrying out normal functioning of the brain. Abnormality in any of these frequency bands of oscillations can lead to impairments in different cognitive and memory functions leading to different pathological conditions of the nervous system. However, the exact role of these neural oscillations in establishing various brain functions is still under investigation. Closed loop deep brain stimulation paradigms with neural oscillations as biomarkers could be used as a mechanism to understand the function of these oscillations. For making use of the neural oscillations as biomarkers to manipulate the frequency band of the oscillation, phase of the oscillation, and stimulation signal are of importance. This paper reviews recent trends in deep brain stimulation systems and their non-invasive counterparts, in the use of phase specific stimulation to manipulate individual neural oscillations. In particular, the paper reviews the methods adopted in different brain stimulation systems and devices for stimulating at a definite phase to further optimize closed loop brain stimulation strategies.

Brain connectivity abnormalities and treatment-induced restorations in patients with cervical dystonia

BACKGROUND

The relationship between brain abnormalities and phenotypic characteristics in cervical dystonia (CD) patients has not been fully established, and little is known about the neuroplastic changes induced by botulinum toxin type A (BoNT-A) treatment.

METHODS

Ninety-two CD patients presenting with rotational torticollis and 45 healthy controls from our database were retrospectively screened. After clinical assessment, the 92 patients underwent baseline magnetic resonance imaging (MRI) followed by a single-dose injection of BoNT-A. Four weeks later, 76 out of the 92 patients were re-evaluated with the Tsui scale for dystonia severity, and 33 out of 76 patients completed post-treatment MRI scanning. Data-driven global brain connectivity and regional homogeneity in tandem with seed-based connectivity analyses were used to examine the functional abnormalities in CD and longitudinal circuit alterations that scaled with clinical response to BoNT-A. Multiple regression models were employed for the prediction analysis of treatment efficacy.

RESULTS

Cervical dystonia patients exhibited elevated baseline connectivity of the right postcentral gyrus with the left dorsomedial prefrontal cortex and right caudate nucleus, which was associated with their symptom severity. BoNT-A reduced excessive functional connectivity between the sensorimotor cortex and right superior frontal gyrus, which was significantly correlated with changes in Tsui score. Moreover, pre-treatment regional homogeneity of the left middle frontal gyrus was linearly related to varied response to treatment.

CONCLUSIONS

Our findings unravel dissociable connectivity of the sensorimotor cortex underlying the pathology of CD and central effects of BoNT-A therapy. Furthermore, baseline regional homogeneity with the left middle frontal gyrus may represent a potential evidence-based marker of patient stratification for BoNT-A therapy in CD.

Cervical Myeloradiculopathy and Atlantoaxial Instability in Cervical Dystonia

OBJECTIVE

Atlantoaxial instability, although rarely reported in the literature, can be associated with cervical dystonia (CD) and may lead to compression of the cord at the craniovertebral junction. We present a case series of 4 patients of longstanding CD with neurologic complications. Treatment strategies and challenges are discussed.

METHODS

Retrospective analysis of 4 cases of longstanding CD with complications of myelopathy or radiculopathy.

RESULTS

The average age at onset of complications was 28 years (range, 17-37). The average duration of CD was 23.75 years. Narrowing of the craniovertebral junction was seen in 3 patients, of which 2 had os odontoideum, and 1 had rotational malalignment at the atlantoaxial joint. One patient had disc desiccation with bulge and intramedullary signal changes in the cord at C3-4 level. Medical treatment was not satisfactory, but botulinum toxin was partly useful in all. One patient had sequelae of myelopathy and did recover partially after deep brain stimulation. Of the 2 patients who underwent surgical fixation with a fusion of the spine, one improved, and the other had no improvement due to irreversible cord damage. The overall outcome was satisfactory only in 2 patients.

CONCLUSIONS

Early-onset CD can lead to cord complications at a young age and at higher levels of the cervical spine and at the cervicovertebral junction. Comprehensive management by a multidisciplinary team is crucial to prevent complications early.

Cervical Dystonia Refractory to Botulinum Toxin Responding to Radiofrequency Ablation: A Case Report

A 62-year-old male diagnosed with cervical dystonia (CD) and chronic right-sided neck pain presented to the Pain Clinic after his pain and CD symptoms failed to resolve with botulinum toxin therapy. During clinical examination, right C3-C4 and C4-C5 facet arthropathy was suspected. After two sets of diagnostic right cervical, C3, C4, and C5 medial branch blocks provided >80% pain relief; cervical radiofrequency ablation (CRFA) was performed. Post CRFA, the patient was followed for 12 months. Till the last follow-up, he was not only experiencing 90% pain relief, but also had significant improvement in his CD symptoms to the point that he no longer needed botulinum toxin and other CD-related therapy. This report suggests that large-scale research is required to postulate whether CD patients, whose symptoms are refractory to botulinum toxin, should be routinely screened for cervical facet arthropathy. This is the first reported case of improvement in CD symptoms with CRFA. This effect could be explained by the fact that certain deep cervical muscles, which are affected in CD, are innervated by medial branch nerves.

Accuracy of Ultrasound-Guided and Non-guided Botulinum Toxin Injection Into Neck Muscles Involved in Cervical Dystonia: A Cadaveric Study

Objective

To compare the accuracy of ultrasound-guided and non-guided botulinum toxin injections into the neck muscles involved in cervical dystonia.

Methods

Two physicians examined six muscles (sternocleidomastoid, upper trapezius, levator scapulae, splenius capitis, scalenus anterior, and scalenus medius) from six fresh cadavers. Each physician injected ultrasound-guided and non-guided injections to each side of the cadaver’s neck muscles, respectively. Each physician then dissected the other physician’s injected muscle to identify the injection results. For each injection technique, different colored dyes were used. Dissection was performed to identify the results of the injections. The muscles were divided into two groups based on the difficulty of access: sternocleidomastoid and upper trapezius muscles (group A) and the levator scapulae, splenius capitis, scalenus anterior, and scalenus medius muscles (group B).

Results

The ultrasound-guided and non-guided injection accuracies of the group B muscles were 95.8% and 54.2%, respectively (p<0.001), while the ultrasound-guided and non-guided injection accuracies of the group A muscles were 100% and 79.2%, respectively (p<0.05).

Conclusion

Ultrasound-guided botulinum toxin injections into inaccessible neck muscles provide a higher degree of accuracy than non-guided injections. It may also be desirable to consider performing ultrasound-guided injections into accessible neck muscles.

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.

Alterations of Interhemispheric Functional Connectivity and Degree Centrality in Cervical Dystonia: A Resting-State fMRI Study

Background

Cervical dystonia (CD) is a neurological movement disorder characterized by involuntary head and neck movements and postures. Reports on microstructural and functional abnormalities in multiple brain regions not limited to the basal ganglia have been increasing in patients with CD. However, the neural bases of CD are unclear. This study is aimed at identifying cerebral functional abnormalities in CD by using resting-state functional magnetic resonance imaging (rs-fMRI).

Methods

Using rs-fMRI data, voxel-mirrored homotopic connectivity (VMHC) and degree centrality were used to compare the alterations of the rs-functional connectivity (FC) between 19 patients with CD and 21 healthy controls. Regions showing abnormal FCs from two measurements were the regions of interest for correlation analyses.

Results

Compared with healthy controls, patients with CD exhibited significantly decreased VMHC in the supplementary motor area (SMA), precuneus (PCu)/postcentral gyrus, and superior medial prefrontal cortex (MPFC). Significantly increased degree centrality in the right PCu and decreased degree centrality in the right lentiform nucleus and left ventral MPFC were observed in the patient group compared with the control group. Further correlation analyses showed that the VMHC values in the SMA were negatively correlated with dystonia severity.

Conclusion

Local abnormalities and interhemispheric interaction deficits in the sensorimotor network (SMA, postcentral gyrus, and PCu), default mode network (MPFC and PCu), and basal ganglia may be the key characteristics in the pathogenesis mechanism of CD.

The therapeutic usage of botulinum toxin (Botox) in non-cosmetic head and neck conditions - An evidence based review

Botulinum toxin (Botox) is an exotoxin produced from Clostridium botulinum. It blocks the release of acetylcholine from the cholinergic nerve end plates resulting in inactivity of the muscles or glands innervated. The efficacy of Botox in facial aesthetics is well established; however, recent literature has highlighted its utilization in multiple non-cosmetic medical and surgical conditions. The present article reviews the current evidence pertaining to Botox use in the non-cosmetic head and neck conditions. A literature search was conducted using MEDLINE, EMBASE, ISI Web of Science and the Cochrane databases limited to English Language articles published from January 1980 to December 2014. The findings showed that there is level 1 evidence supporting the efficacy of Botox in the treatment of laryngeal dystonia, headache, cervical dystonia, masticatory myalgia, sialorrhoea, temporomandibular joint disorders, bruxism, blepharospasm, hemifacial spasm and rhinitis. For chronic neck pain there is level 1 evidence to show that Botox is ineffective. Level 2 evidence exists for vocal tics and trigeminal. For stuttering, facial nerve paresis, Frey's syndrome and oromandibular dystonia the evidence is level 4. Thus, there is compelling evidence in the published literature to demonstrate the beneficial role of Botox in a wide range of non-cosmetic conditions pertaining to the head and neck (mainly level 1 evidence). With more and more research, the range of clinical applications and number of individuals getting Botox will doubtlessly increase. Botox appears to justify its title as 'the poison that heals'.

Bruxism in craniocervical dystonia: a prospective study

AIMS

Bruxism pathophysiology remains unclear, and its occurrence has been poorly investigated in movement disorders. The aim of this study was to compare the frequency of bruxism in patients with craniocervical dystonia vs. normal controls and to determine its associated clinical features.

METHOD

This is a prospective-control study. A total of 114 dystonic subjects (45 facial dystonia, 69 cervical dystonia) and 182 controls were included. Bruxism was diagnosed using a hetero-questionnaire and a clinical examination performed by trained dentists. Occurrence of bruxism was compared between the different study populations. A binomial logistic regression analysis was used to determine which clinical features influenced bruxism occurrence in each population.

RESULTS

The frequency of bruxism was significantly higher in the dystonic group than in normal controls but there was no difference between facial and cervical dystonia. It was also higher in women than in men. Bruxism features were similar between normal controls and dystonic patients except for a higher score of temporomandibular jaw pain in the dystonic group.

DISCUSSION

The higher frequency of bruxism in dystonic patients suggests that bruxism is increased in patients with basal ganglia dysfunction but that its nature does not differ from that seen in bruxers from the normal population.

AbobotulinumtoxinA in the management of cervical dystonia in the United Kingdom: a budget impact analysis

BACKGROUND

Cervical dystonia (CD) can be effectively managed by a combination of botulinum neurotoxin A (BoNT-A) and conventional therapy (skeletal muscle relaxants and rehabilitative therapy), but the costs of different interventions in the UK vary.

METHODS

A budget impact model was developed from the UK payer perspective with a 5-year time horizon to evaluate the effects of changing market shares of abobotulinumtoxinA, onabotulinumtoxinA, and incobotulinumtoxinA, and best supportive care from the UK payer perspective. Epidemiological and resource use data were retrieved from the published literature and clinical expert opinion. Deterministic sensitivity analyses were performed to determine the parameters most influential on the budgetary findings under base case assumptions.

RESULTS

Under base case assumptions, an increased uptake of abobotulinumtoxinA showed an accumulated savings of £2,250,992 by year 5. Treatment per patient per year with onabotulinumtoxinA and incobotulinumtoxinA costs more when compared to treatment with abobotulinumtoxinA. One-way sensitivity analyses showed that the prevalence of CD, dose per injection of each of the BoNT-As, and time to reinjection of incobotulinumtoxinA and abobotulinumtoxinA influenced the base case findings most.

CONCLUSION

There is potential for cost savings associated with the greater use of abobotulinumtoxinA rather than other BoNT-A treatments, permitting more patients to benefit more from effective BoNT-A treatment with a fixed budget.

The effectiveness of physiotherapy for cervical dystonia: a systematic literature review

Cervical dystonia is a form of adult-onset, focal dystonia characterized by involuntary contractions of the neck muscles, leading to a disabling, abnormal head posture. CD has a great impact on the activities of daily living (ADL) and quality of life. Currently, the most widely used and recommended first line treatment is botulinum toxin type A (BoNT/A) injections. Physiotherapy is a potentially useful adjuvant, but little is known about its effectiveness. Consequently, our objective was to investigate the effectiveness of physiotherapy alone or as an adjuvant treatment to BoNT/A injections in cervical dystonia (CD) by means of a systematic literature review. Two online databases, PubMed and Web of Science, were searched for articles describing the effectiveness of physiotherapy treatment for CD. After screening, based on predefined in- and exclusion criteria, 16 studies were retained. Their methodological quality was assessed according to Cochrane guidelines. The methodological quality of most studies was low. Examples of shortcomings are small sample sizes, lack of randomization or blinding, and diversity in therapeutic techniques and outcome measures. Only seven studies were clinical trials; the remaining were either case reports or case series. The reported physiotherapy treatments included EMG biofeedback training, muscular elongation, postural exercises and electrotherapy. Improvements in head position, pain, cervical range of motion, quality of life and ADL have been reported, which is promising. Cautious interpretation on the effectiveness of physiotherapy as an adjuvant therapy is required. Before firm conclusions can be drawn, additional high quality trials are needed.

Torticollis

Torticollis refers to a twisting of the head and neck caused by a shortened sternocleidomastoid muscle, tipping the head toward the shortened muscle, while rotating the chin in the opposite direction. Torticollis is seen at all ages, from newborns to adults. It can be congenital or postnatally acquired. In this review, we offer a new classification of torticollis, based on its dynamic qualities and pathogenesis. All torticollis can be classified as either nonparoxysmal (nondynamic) or paroxysmal (dynamic). Causes of nonparoxysmal torticollis include congenital muscular; osseous; central nervous system/peripheral nervous system; ocular; and nonmuscular, soft tissue. Causes of paroxysmal torticollis are benign paroxysmal; spasmodic (cervical dystonia); Sandifer syndrome; drugs; increased intracranial pressure; and conversion disorder. The description, epidemiology, clinical presentation, evaluation, treatment, and prognosis of the most clinically significant types of torticollis follow.

Dystonia and the cerebellum: a new field of interest in movement disorders?

Although dystonia has traditionally been regarded as a basal ganglia dysfunction, recent provocative evidence has emerged of cerebellar involvement in the pathophysiology of this enigmatic disease. This review synthesizes the data suggesting that the cerebellum plays an important role in dystonia etiology, from neuroanatomical research of complex networks showing that the cerebellum is connected to a wide range of other central nervous system structures involved in movement control to animal models indicating that signs of dystonia are due to cerebellum dysfunction and completely disappear after cerebellectomy, and finally to clinical observations in secondary dystonia patients with various types of cerebellar lesions. We propose that dystonia is a large-scale dysfunction, involving not only cortico-basal ganglia-thalamo-cortical pathways, but the cortico-ponto-cerebello-thalamo-cortical loop as well. Even in the absence of traditional "cerebellar signs" in most dystonia patients, there are more subtle indications of cerebellar dysfunction. It is clear that as long as the cerebellum's role in dystonia genesis remains unexamined, it will be difficult to significantly improve the current standards of dystonia treatment or to provide curative treatment.

An evidence-based review of botulinum toxin (Botox) applications in non-cosmetic head and neck conditions

Botulinum toxin (Botox) is an exotoxin produced from Clostridium botulinum. It works by blocking the release of acetylcholine from the cholinergic nerve end plates leading to inactivity of the muscles or glands innervated. Botox is best known for its beneficial role in facial aesthetics but recent literature has highlighted its usage in multiple non-cosmetic medical and surgical conditions. This article reviews the current evidence pertaining to Botox use in the head and neck. A literature review was conducted using The Cochrane Controlled Trials Register, Medline and EMBASE databases limited to English Language articles published from 1980 to 2012. The findings suggest that there is level 1 evidence supporting the efficacy of Botox in the treatment of spasmodic dysphonia, essential voice tremor, headache, cervical dystonia, masticatory myalgia, sialorrhoea, temporomandibular joint disorders, bruxism, blepharospasm, hemifacial spasm and rhinitis. For chronic neck pain there is level 1 evidence to show that Botox is ineffective. Level 2 evidence exists for vocal tics, trigeminal neuralgia, dysphagia and post-laryngectomy oesophageal speech. For stuttering, 'first bite syndrome', facial nerve paresis, Frey's syndrome, oromandibular dystonia and palatal/stapedial myoclonus the evidence is level 4. Thus, the literature highlights a therapeutic role for Botox in a wide range of non-cosmetic conditions pertaining to the head and neck (mainly level 1 evidence). With ongoing research, the spectrum of clinical applications and number of people receiving Botox will no doubt increase. Botox appears to justify its title as 'the poison that heals'.

An open-label cohort study of the improvement of quality of life and pain in de novo cervical dystonia patients after injections with 500 U botulinum toxin A (Dysport)

OBJECTIVES

It remains to be determined whether the benefits of botulinum toxin type A (BoNT-A) on cervical dystonia (CD) motor symptoms extend to improvements in patient's quality of life (QoL). This analysis of a large, multicentre study was conducted with the aim of investigating changes in QoL and functioning among de novo patients receiving 500 U BoNT-A (abobotulinumtoxinA; Dysport) for the treatment of the two most frequent forms of CD, predominantly torticollis and laterocollis.

DESIGN

A prospective, open-label study of Dysport (500 U; Ipsen Biopharm Ltd) administered according to a defined intramuscular injection algorithm.

SETTING

German and Austrian outpatient clinics.

PARTICIPANTS

516 male and female patients (aged ≥18 years) with de novo CD. The majority of patients had torticollis (78.1%). 35 patients had concomitant depression (MedDRA-defined).

MAIN OUTCOME MEASURES

Change from baseline to weeks 4 and 12 in Craniocervical Dystonia Questionnaire (CDQ-24) total and subscale scores, patient diary items ('day-to-day capacities and activities', 'pain' and 'duration of pain') and global assessment of pain.

RESULTS

Significant improvements were observed in CDQ-24 total and subscale scores at week 4 and were sustained up to week 12 (p<0.001). Changes in CDQ-24 scores did not significantly differ between the torticollis and laterocollis groups or between patients with or without depression. There were also significant reductions in patient diary item scores for activities of daily living, pain and pain duration at weeks 4 and 12 (p<0.001). Pain relief (less or no pain) was reported by 66% and 74.1% of patients at weeks 4 and 12, respectively. Changes in pain parameters demonstrated a positive relationship with change in Tsui score.

CONCLUSIONS

After standardised open-label treatment with Dysport 500 U, improvements in QoL and pain intensity up to 12 weeks in patients with CD were observed.

Mutations in ANO3 cause dominant craniocervical dystonia: ion channel implicated in pathogenesis

In this study, we combined linkage analysis with whole-exome sequencing of two individuals to identify candidate causal variants in a moderately-sized UK kindred exhibiting autosomal-dominant inheritance of craniocervical dystonia. Subsequent screening of these candidate causal variants in a large number of familial and sporadic cases of cervical dystonia led to the identification of a total of six putatively pathogenic mutations in ANO3, a gene encoding a predicted Ca(2+)-gated chloride channel that we show to be highly expressed in the striatum. Functional studies using Ca(2+) imaging in case and control fibroblasts demonstrated clear abnormalities in endoplasmic-reticulum-dependent Ca(2+) signaling. We conclude that mutations in ANO3 are a cause of autosomal-dominant craniocervical dystonia. The locus DYT23 has been reserved as a synonym for this gene. The implication of an ion channel in the pathogenesis of dystonia provides insights into an alternative mechanism that opens fresh avenues for further research.

Topography of dyskinesias and torticollis evoked by inhibition of substantia nigra pars reticulata

GABAergic neurons of the substantia nigra pars reticulata (SNpr) and globus pallidus pars interna (GPi) constitute the output pathways of the basal ganglia. In monkeys, choreiform limb dyskinesias have been described after inhibition of the GPi, but not the SNpr. Given the anatomical and functional similarities between these structures, we hypothesized that choreiform dyskinesias could be evoked by inhibition of an appropriate region within the SNpr. The GABAA receptor agonist, muscimol, was infused into various sites within the SNpr and the adjacent STN of freely moving macaques. The effect of the GABAA antagonist, bicuculline (BIC), was also examined. Muscimol (MUS) in SNpr evoked the following: (1) choreiform dyskinesias of the contralateral arm and/or leg from central and lateral sites; (2) contralaterally directed torticollis from central and posterior sites; and (3) contraversive quadrupedal rotation from anterior and lateral sites. MUS infusions into the adjacent SN pars compacta or STN were without effect, ruling out a contribution of drug spread to adjacent structures. BIC in SNpr induced ipsiversive postures without choreiform dyskinesia or torticollis, whereas in the STN, it evoked ballistic movements. This is the first report of choreiform dyskinesia evoked by inhibition of the SNpr. This highly site-specific effect was obtained from a restricted region within the SNpr distinct from that responsible for inducing torticollis. These results suggest that overactivity of different SNpr outputs mediates choreiform dyskinesia and torticollis. These abnormalities are symptoms of dystonia, Huntington's disease, and iatrogenic dyskinesias, suggesting that these conditions may result, in part, from a loss of function in SNpr efferent projections.

Spasmodic torticollis: the dental connection

Spasmodic torticollis or cervical dystonia (CD) is the most common form of focal dystonia and is characterized by sustained abnormal muscle contractions in the head and neck area resulting in abnormal positioning or posturing of the head. The dystonic muscle spasms associated with spasmodic torticollis may affect any combination of neck muscles. Three cases are reported of spasmodic torticollis that were treated by a dental appliance with individual varying occlusal heights to open the maxillomandibular vertical dimension. Upon increasing the vertical dimension of occlusion, there was a slowing and/or discontinuance of the symptoms of cervical dystonia. The proposed hypothesis for this reversal is that there may be neuritis of the auriculotemporal branch of the trigeminal nerve, which has direct input into the reticular formation (RF), and it may activate the cells of the pontine region of the RF known for the control and deviation of head posture. There is growing clinical evidence that temporomandibular joint (TMJ) dysfunction may be a factor in this neurological and painful disorder when it coexists.

Posttraumatic focal dystonia of the shoulder

Focal posttraumatic shoulder dystonia is a rare and not easily identifiable entity. Its true pathophysiologic nature, predisposing factors, and disease course remain debatable.This article describes a rare case of a 40-year-old man with late symptoms of focal shoulder dystonia after peripheral trauma of his left shoulder girdle. The shoulder was indirectly injured from the impact of a fall off his motorbike 3 years earlier. He was referred to the authors' institution because remarkable reduction of arm abduction, muscle spasms, and circumscribed hypertrophy of the trapezius muscle were noted while his head and neck were in neutral position and had a full range of motion. The left shoulder had a fixed elevated posture compared with the contralateral shoulder. A continuous burning pain was localized over the area of the hypertrophied trapezius muscle, radiating to the ipsilateral side of the head and neck. Dystonic movements of the trapezius, rhomboid, and supraspinatus muscles were observed. The abduction of the shoulder was significantly decreased, and any repetitive effort for arm abduction induced an exaggeration of his movement disorder, leading to a more pronounced shoulder elevation.Plain radiographs and magnetic resonance imaging of the left shoulder revealed a suprascapular tendinitis with no other abnormalities. Repeated needle electromyography of the left trapezius muscle and neurography of the accessory nerve on both sides were normal. Injections of botulinum toxin A were effective in the resolution of muscle hypertrophy and abnormal posture.

Botulinum toxin A (Dysport®): in dystonias and focal spasticity

Dysport®, a formulation of botulinum toxin A, blocks acetylcholine release at neuromuscular junctions causing denervation and temporary muscle paralysis. It is used to treat several medical conditions, including dystonias and focal spasticity. Subcutaneous Dysport® was effective in improving functional disability in adults with blepharospasm in a placebo-controlled trial with 16 weeks' follow-up, and in adults with hemifacial spasm in case series. Similarly, intramuscular Dysport® was effective in improving symptoms of cervical dystonia in adults, focal spasticity in adults with post-stroke upper limb spasticity and dynamic equinus spasticity in paediatric patients with cerebral palsy in placebo-controlled trials with up to 20 weeks' follow-up. However, in two 12-week, placebo-controlled trials in adults with focal lower limb spasticity (spastic equinovarus deformity after stroke and hip adductor spasticity associated with multiple sclerosis) intramuscular Dysport® had limited efficacy. Available longer-term data indicated that Dysport® treatment was effective over several treatment cycles in patients with cervical dystonia or upper limb spasticity. Dysport® was generally well tolerated in patients with dystonias or focal spasticity. Most adverse events were mild to moderate and transient.

Factors influencing response to Botulinum toxin type A in patients with idiopathic cervical dystonia: results from an international observational study

OBJECTIVES

Real-life data on response to Botulinum toxin A (BoNT-A) in cervical dystonia (CD) are sparse. An expert group of neurologists was convened with the overall aim of developing a definition of treatment response, which could be applied in a non-interventional study of BoNT-A-treated subjects with CD.

DESIGN

International, multicentre, prospective, observational study of a single injection cycle of BoNT-A as part of normal clinical practice.

SETTING

38 centres across Australia, Belgium, Czech Republic, France, Germany, The Netherlands, Portugal, Russia and the UK.

PARTICIPANTS

404 adult subjects with idiopathic CD. Most subjects were women, aged 41-60 years and had previously received BoNT-A.

OUTCOME MEASURES

Patients were classified as responders if they met all the following four criteria: magnitude of effect (≥25% improvement Toronto Western Spasmodic Torticollis Rating Scale), duration of effect (≥12-week interval between the BoNT-A injection day and subject-reported waning of treatment effect), tolerability (absence of severe related adverse event) and subject's positive Clinical Global Improvement (CGI).

RESULTS

High rates of response were observed for magnitude of effect (73.6%), tolerability (97.5%) and subject's clinical global improvement (69.8%). The subjective duration of effect criterion was achieved by 49.3% of subjects; 28.6% of subjects achieved the responder definition. Factors most strongly associated with response were age (<40 years; OR 3.9, p<0.05) and absence of baseline head tremor (OR 1.5; not significant).

CONCLUSIONS

Three of four criteria were met by most patients. The proposed multidimensional definition of response appears to be practical for routine practice. Unrealistically high patient expectation and subjectivity may influence the perception of a quick waning of effect, but highlights that this aspect may be a hurdle to response in some patients. CLINICAL REGISTRATION NUMBER: (NCT00833196; ClinicalTrials.gov).

Cervical dystonia

Cervical dystonia is a common disorder with significant associated morbidity. Although limited benefit can be derived from oral pharmacologic agents, the advent of botulinum neurotoxin (BoNT) injection has provided a valuable tool in the treatment of this disorder. In order to provide effective treatment, the physician must have an intimate knowledge of the anatomy and function of the neck musculature. Novel BoNT formulations, even of the same serotype, are not equivalent and thus require careful dose titration. Formulation improvements may result in reduced immunoresistance. In patients labeled as treatment resistant to BoNT, careful electromyographic reassessment of select muscles for injection will frequently result in improved clinical benefit.

Cervical dystonia: disease profile and clinical management

Cervical dystonia, the most common focal dystonia, frequently results in cervical pain and disability as well as impairments affecting postural control. The predominant treatment for cervical dystonia is provided by physicians, and treatment can vary from pharmacological to surgical. Little literature examining more conservative approaches, such as physical therapy, exists. This article reviews the etiology and pathophysiology of the disease as well as medical and physical therapist management for people with cervical dystonia.

Prevalence of cervical dystonia and spasmodic torticollis in the United States general population

PURPOSE

To examine the prevalence of cervical dystonia (CD) in the US population.

METHOD

A survey consisting of relevant demographic and CD-related questions was e-mailed to 2 million people selected from the Shopper's Voice database.

RESULTS

Across a census-weighted sample, 0.280% of 60,062 respondents (79% female, 92% Caucasian) reported a diagnosis of CD and 0.170% reported a diagnosis of ST, indicating possible prevalence of 0.390% of either/both diagnoses. Less than half (42.7%) of those who reported either diagnosis were receiving treatment.

CONCLUSIONS

CD is potentially under-diagnosed and under-treated; approaches to increase awareness of CD and its treatments are needed.

The management of cervical dystonia

Cervical dystonia (CD), also known as 'spasmodic torticollis', is the most common form of adult-onset focal dystonia. It is a chronic disorder for which there is no curative treatment. Proposed interventions only have a symptomatic effect that is directed at controlling the intensity of the dystonic contractions and their associated symptoms. Both serotypes of botulinum toxin (BtA and BtB) have shown efficacy for the treatment of CD, and they constitute the first-line therapy for CD. BtB constitutes the best medical treatment for secondary failures to BtA. The efficacy of all other proposed medications, including anticholinergics, should be considered unknown due to the lack of good-quality trials. This lack of evidence applies also to all physical rehabilitation treatments. Although the authors have concluded that all surgical procedures for CD should still be considered investigational, the best data supporting benefit of surgery comes from case series of selective peripheral denervation and pallidal deep brain stimulation.

Ballism after stroke responds to standard physical therapeutic interventions

OBJECTIVE

To report the effects of noninvasive standard physical therapy (PT) interventions on an involuntary movement disorder after stroke.

DESIGN

Single case with clinical follow-up over 2 years.

SETTING

Inpatient stroke and rehabilitation services and outpatient clinic.

PARTICIPANT

A man with acute bilateral ballism after unilateral subthalamic infarction.

INTERVENTIONS

Rhythmic coordinated bilateral limb movements and firm tactile stimulation to the hand.

MAIN OUTCOME MEASURES

We had not anticipated that dyskinesia itself would specifically improve during treatment. Consequently, we used qualitative clinical observations, including review of videotaped performance, and self-reported limb control. Hypotheses concerning treatment effects were developed after data collection.

RESULTS

Involuntary movements recurrently improved within treatment sessions.

CONCLUSIONS

PT may improve dyskinesia after stroke. The benefit may be adjunctive or alternative to current invasive treatments of movement disorders after brain injury and merits confirmation. The improvements are consistent with current research indicating that (1) intact cortical, subcortical, cerebellar, and spinal areas interact to generate bilateral rhythmic limb movements that can overcome dyskinesia and (2) tactile stimulation can improve motor deficits associated with basal ganglia disorders. Finally, because functional activities assessments improved our evaluation of ballism, these should be routinely used along with conventional neurologic examination to assess involuntary movement disorders.

Reduction of cervical dystonia after an extended course of chiropractic manipulation: a case report

OBJECTIVE

The diminution of the signs and symptoms of cervical dystonia following an extended course of specific chiropractic manipulation is described.

CLINICAL FEATURES

A 38-year-old man had gross anterior-lateral torticollis, focal dystonia of the head and neck, and radicularlike pains which failed to respond to physical therapy, medication, and injection.

INTERVENTIONS AND OUTCOMES

Two specific spinal manipulative technique systems unique to the chiropractic profession (Applied Biostructural Therapy [ABT] and Atlas Coccygeal Technique [ACT]) were applied to the patient. The patient's grading on a modified cervical dystonia scale dropped from a grade 16 to a grade 5 after an extended course of these specific chiropractic manipulative techniques.

CONCLUSIONS

The application of Advanced Biostructural Therapy and Atlas Coccygeal chiropractic techniques for management of cervical dystonia is presented. Substantial reduction in the cervical dystonia rating scale was observed with this approach, even after standard medical interventions had failed.

Botox: beyond wrinkles

First used and approved over a decade ago for the treatment of strabismus (or misaligned eyes), botulinum toxin (BTX) has demonstrated efficacy in blepharospasm, hemifacial spasm, spastic lower eyelid entropion, and a number of other disorders seen in the traditional medical environment that are characterized by abnormal muscle contraction. Moreover, other conditions-notably some pain and gastrointestinal disorders-have responded to BTX injections.

Botulinum toxin therapy for cervical dystonia

Botulinum toxin revolutionized the treatment of cervical dystonia. In contrast to systemically active medications, the effect of botulinum toxin results from selective administration to weaken muscles involved in the dystonic posturing of the head. This article reviews the pathophysiologic basis of symptoms in cervical dystonia and how botulinum toxin alleviates them. Other therapeutic options are reviewed for comparison. This article discusses strategies for maximizing the clinical benefit of botulinum toxin in this disorder and reviews muscle selection and identification with electromyography.

Injectable neuromuscular blockade in the treatment of spasticity and movement disorders

Neuromuscular blockade via injection of alcohol, phenol, or botulinum toxin reduces the tone of overactive muscles in order to restore the appropriate balance between agonists and antagonists. Such a restoration allows improved stretch and increased resting length and can reduce the likelihood of contracture. Alcohol or phenol, injected onto the motor nerve, denatures proteins and promotes axonal degeneration. The onset of action is within hours, whereas the duration of action is variable, ranging from 2 weeks to 6 months and beyond. The advantages of alcohol or phenol chemodenervation lie in their low cost and lack of antigenicity. The disadvantages include the technical difficulty of the injections and significant risk for pain as a result of treatment. Botulinum toxins, purified forms of Clostridium botulinum exotoxins, are injected directly into muscle, where they cleave one or more vesicle fusion proteins, thus blocking release of acetylcholine at the neuromuscular junction. Three commercial products--two of serotype A and one of B--are available. Each differs in its unit potency, side effects, and duration of action. On average, botulinum toxin has a clinical onset of action approximately 12 to 72 hours after injection, with a peak effect at 1 to 3 weeks. Effects then plateau for 1 to 2 months, with patients often requiring reinjection approximately every 3 months. Side effects may include local discomfort at the site of the injection and excessive weakness of the injected or nearby muscles, although more distant effects may occur. Antibody formation is a significant clinical concern and eventually obviates treatment benefit in approximately 5% of patients. Switching serotypes may be effective, at least temporarily. Consensus dosing guidelines have been developed and are presented within. Numerous studies have suggested that botulinum toxin has a role in the care of children with spasticity or dystonia related to cerebral palsy, and may improve equinus, gait, upper extremity use, comfort, and care. Evidence of functional improvement remains equivocal in the severely impaired child; however, there is evidence for improvement in less impaired children. The optimal candidate for injectable neuromuscular blockade is one who has a limited number of muscles that need treatment, who does not have fixed contracture, and who retains selective motor control. The ultimate goal of treatment for the hypertonic child is to maximize function, comfort, and independence. Hypertonia is only one aspect of the upper motoneuron syndrome, which includes both positive and negative symptoms. The treatment program, in which chemodenervation is only one tool, requires a multidisciplinary evaluation and individualized plan to address the whole patient.

Metallic taste: an unusual reaction to botulinum toxin A

BACKGROUND

Botulinum neurotoxin formulations are safe and effective agents for the treatment of facial rhytides.

OBJECTIVES

A patient is described who complained of metallic taste after each treatment with botulinum toxin A (BTX-A).

RESULTS

The sensation of metallic taste diminished after successive treatments with BTX-A, despite adequate dosing for cosmetic purposes.

CONCLUSION

Metallic taste is associated with the use of numerous medications; however, the pathogenesis remains unclear. Alteration in zinc metabolism, which may occur with BTX-A administration, has been suggested as a possible mechanism. Although this is the first known report of dysgeusia after BTX-A, physicians and patients may be reassured that the taste alteration was self-limited and was not significantly problematic for the patient in our case.

Treatment of dystonia

Therapeutic strategies in the treatment of dystonia consist primarily of pharmacologic, surgical, and supportive approaches. Many recent advances have been made in the treatment of dystonia with newer medications, availability of different botulinum toxins, and surgical procedures. However, these treatment modalities all have limiting factors and varying levels of efficacy. Studies range from case reports and open-label trials to double-blind placebo-controlled trials. More research and larger studies are needed to explore these newer medications and surgical techniques for both primary focal and generalized dystonia. Studies in functional outcome and quality of life further support the importance of discovering safe and effective means to treat dystonia. An algorithmic approach may be useful to guide the physician along the various treatment choices.

Review of the FDA-approved uses of botulinum toxins, including data suggesting efficacy in pain reduction

Botulinum toxin has dramatically improved the treatment of a variety of neurologic disorders. Two botulinum toxin preparations are commercially available in the United States: type A (Botox) and type B (Myobloc). Current indications approved by the United States Food and Drug Administration include cervical dystonia, strabismus, blepharospasm, hemifacial spasm, and glabellar wrinkles for Botox, and cervical dystonia for Myobloc. Botulinum toxin inhibits release of acetylcholine from the neuromuscular junction, resulting in a localized paralysis when minute doses are injected. This mechanism enables botulinum toxin to alleviate symptoms of focal dystonias (which are characterized by excessive muscle contraction), and it may also, along with other theoretical mechanisms, be responsible for pain relief. Studies conducted in patients with cervical dystonia have shown that botulinum toxin effectively reduces pain associated with this disorder, suggesting that this agent may be effective in alleviating other painful syndromes.