Experimental spasmodic torticollis

Physiology of Dystonia: Animal Studies

Dystonia is currently ranked as the third most prevalent motor disorder. It is typically characterized by involuntary muscle over- or co-contractions that can cause painful abnormal postures and jerky movements. Dystonia is a heterogenous disorder-across patients, dystonic symptoms vary in their severity, body distribution, temporal pattern, onset, and progression. There are also a growing number of genes that are associated with hereditary dystonia. In addition, multiple brain regions are associated with dystonic symptoms in both genetic and sporadic forms of the disease. The heterogeneity of dystonia has made it difficult to fully understand its underlying pathophysiology. However, the use of animal models has been used to uncover the complex circuit mechanisms that lead to dystonic behaviors. Here, we summarize findings from animal models harboring mutations in dystonia-associated genes and phenotypic animal models with overt dystonic motor signs resulting from spontaneous mutations, neural circuit perturbations, or pharmacological manipulations. Taken together, an emerging picture depicts dystonia as a result of brain-wide network dysfunction driven by basal ganglia and cerebellar dysfunction. In the basal ganglia, changes in dopaminergic, serotonergic, noradrenergic, and cholinergic signaling are found across different animal models. In the cerebellum, abnormal burst firing activity is observed in multiple dystonia models. We are now beginning to unveil the extent to which these structures mechanistically interact with each other. Such mechanisms inspire the use of pre-clinical animal models that will be used to design new therapies including drug treatments and brain stimulation.

Botulinum toxin type A versus anticholinergics for cervical dystonia

BACKGROUND

This is an update of a Cochrane Review first published in 2005. Cervical dystonia is the most common form of focal dystonia and is a highly disabling movement disorder, characterised by involuntary, usually painful, head posturing. Currently, botulinum toxin type A (BtA) is considered the first line therapy for this condition. Before BtA, anticholinergics were the most widely accepted treatment.

OBJECTIVES

To compare the efficacy, safety, and tolerability of BtA versus anticholinergic drugs in adults with cervical dystonia.

SEARCH METHODS

We searched the Cochrane Movement Disorders' Trials Register to June 2003, screened reference lists of articles and conference proceedings to September 2018, and searched CENTRAL, MEDLINE, and Embase, with no language restrictions, to July 2020.

SELECTION CRITERIA

Double-blind, parallel, randomised trials (RCTs) of BtA versus anticholinergic drugs in adults with cervical dystonia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed records, selected included studies, extracted data using a paper pro forma, and evaluated the risk of bias and quality of the evidence. We resolved disagreements by consensus or by consulting a third review author. If enough data had been available, we were to perform meta-analyses using a random-effects model for the comparison of BtA versus anticholinergic drugs to estimate pooled effects and corresponding 95% confidence intervals (95% CI). The primary efficacy outcome was improvement in cervical dystonia-specific impairment. The primary safety outcome was the proportion of participants with any adverse event.

MAIN RESULTS

We included one RCT of moderate overall risk of bias (as multiple domains were at unclear risk of bias), which included 66 BtA-naive participants with cervical dystonia. Two doses of BtA (Dysport; week 0 and 8; mean dose 262 to 292 U) were compared with daily trihexyphenidyl (up to 24 mg daily). The trial was sponsored by the BtA producer. BtA reduced cervical dystonia severity by an average of 2.5 points (95% CI 0.68 to 4.32) on the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) severity subscale 12 weeks after injection, compared to trihexyphenidyl. More participants reported adverse events in the trihexyphenidyl treatment group (76 events), compared with the BtA group (31 events); however, the difference in dropouts due to adverse events was inconclusive between groups. There was a decreased risk of dry mouth, and memory problems with BtA, but the differences were inconclusive between groups for the other reported side effects (blurred vision, dizziness, depression, fatigue, pain at injection site, dysphagia, and neck weakness).

AUTHORS' CONCLUSIONS

We found very low-certainty evidence that BtA is more effective, better tolerated, and safer than trihexyphenidyl. We found no information on a dose-response relationship with BtA, differences between BtA formulations or different anticholinergics, the utility of electromyography-guided injections, or the duration of treatment effect.

Botulinum toxin type A therapy for cervical dystonia

BACKGROUND

This is an update of a Cochrane Review first published in 2005. Cervical dystonia is the most common form of focal dystonia, and is a highly disabling movement disorder, characterised by involuntary, usually painful, head posturing. Currently, botulinum toxin type A (BtA) is considered the first line therapy for this condition.

OBJECTIVES

To compare the efficacy, safety, and tolerability of BtA versus placebo, in people with cervical dystonia.

SEARCH METHODS

We searched Cochrane Movement Disorders' Trials Register, CENTRAL, MEDLINE, Embase, reference lists of articles, and conference proceedings in July 2020. All elements of the search, with no language restrictions, were last run in July 2020.

SELECTION CRITERIA

Double-blind, parallel, randomised, placebo-controlled trials (RCTs) of BtA versus placebo in adults with cervical dystonia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed records, selected included studies, extracted data using a paper pro forma, and evaluated the risk of bias. We resolved disagreements by consensus or by consulting a third review author. We performed meta-analyses using a random-effects model, for the comparison of BtA versus placebo, to estimate pooled effects and corresponding 95% confidence intervals (95% CI). We performed preplanned subgroup analyses according to BtA dose used, the BtA formulation used, and the use (or not) of guidance for BtA injections. The primary efficacy outcome was improvement in cervical dystonia-specific impairment. The primary safety outcome was the proportion of participants with any adverse event.

MAIN RESULTS

We included nine RCTs, with moderate, overall risk of bias, that included 1144 participants with cervical dystonia. Seven studies excluded participants with poorer responses to BtA treatment, therefore, including an enriched population with a higher probability of benefiting from this therapy. Only one trial was independently funded. All RCTs evaluated the effect of a single BtA treatment session, using doses from 150 U to 500 U of onabotulinumtoxinA (Botox), 120 U to 240 U of incobotulinumtoxinA (Xeomin), and 250 U to 1000 U of abobotulinumtoxinA (Dysport). BtA resulted in a moderate to large improvement from the participant's baseline clinical status, assessed by the investigators, with a mean reduction of 8.09 points in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS total score) at week four after injection (95% CI 6.22 to 9.96; I² = 0%) compared to placebo. This corresponded, on average, to a 18.4% improvement from baseline. The mean difference (MD) in TWSTRS pain subscore at week four was 2.11 (95% CI 1.38 to 2.83; I² = 0%) compared to placebo. Overall, both participants and clinicians reported an improvement of subjective clinical status. It was unclear if dropouts due to adverse events differed (risk ratio (RR) 2.51; 95% CI 0.42 to 14.94; I² = 0%) However, BtA treatment increased the risk of experiencing an adverse event (R) 1.23; 95% CI 1.05 to 1.43; I² = 28%). Neck weakness (14%; RR 3.40; 95% CI 1.19 to 9.71; I² = 15%), dysphagia (11%; RR 3.19; 95% CI 1.79 to 5.70; I² = 0%), and diffuse weakness or tiredness (8%; RR 1.80; 95% CI 1.10 to 2.95; I² = 0%) were the most common treatment-related adverse events. Treatment with BtA resulted in a decreased risk of dropouts. We have moderate certainty in the evidence across all of the aforementioned outcomes, with the exception of subjective assessment and tolerability, in which we have high confidence in the evidence. We found no evidence supporting the existence of a clear dose-response relationship between BtA and improvement in cervical dystonia-specific impairment, a destinction between BtA formulations, or a variation with use of EMG-guided injection for efficacy outcomes. Due to clinical heterogeneity, we did not pool health-related quality of life data, duration of clinical effect, or the development of secondary non-responsiveness.

AUTHORS' CONCLUSIONS

We are moderately certain in the evidence that a single BtA treatment session resulted in a clinically relevant reduction of cervical dystonia-specific impairment, and pain, and highly certain that it is well tolerated, compared with placebo. There is moderate-certainty evidence that people treated with BtA are at an increased risk of developing adverse events, most notably, dysphagia, neckweakness and diffuse weakness or tiredness. There are no data from RCTs evaluating the effectiveness and safety of repeated BtA injection cycles. There is no evidence from RCTs to allow us to draw definitive conclusions on the optimal treatment intervals and doses, the usefulness of guidance techniques for injection, the impact on quality of life, or the duration of treatment effect.

Botulinum toxin type A therapy for cervical dystonia

BACKGROUND

This is an update of a Cochrane Review first published in 2005. Cervical dystonia is the most common form of focal dystonia and is a highly disabling movement disorder characterised by involuntary, usually painful, head posturing. Currently, botulinum toxin type A (BtA) is considered the first line therapy for this condition.

OBJECTIVES

To compare the efficacy, safety, and tolerability of botulinum toxin type A (BtA) versus placebo in people with cervical dystonia.

SEARCH METHODS

To identify studies for this review we searched Cochrane Movement Disorders' Trials Register, CENTRAL, MEDLINE, Embase, reference lists of articles and conference proceedings. All elements of the search, with no language restrictions, were run in October 2016.

SELECTION CRITERIA

Double-blind, parallel, randomised, placebo-controlled trials (RCTs) of BtA versus placebo in adults with cervical dystonia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed records, selected included studies, extracted data using a paper pro forma, and evaluated the risk of bias. We resolved disagreements by consensus or by consulting a third review author. We performed meta-analyses using a random-effects model for the comparison of BtA versus placebo to estimate pooled effects and corresponding 95% confidence intervals (95% CI). In addition, we performed preplanned subgroup analyses according to BtA dose used, the BtA formulation used, and the use or not of guidance for BtA injection. The primary efficacy outcome was improvement in cervical dystonia-specific impairment. The primary safety outcome was the proportion of participants with any adverse event.

MAIN RESULTS

We included eight RCTs of moderate overall risk of bias, including 1010 participants with cervical dystonia. Six studies excluded participants with poorer responses to BtA treatment, therefore including an enriched population with a higher probability of benefiting from this therapy. Only one trial was independently funded. All RCTs evaluated the effect of a single BtA treatment session, using doses from 150 U to 236 U of onabotulinumtoxinA (Botox), 120 U to 240 U of incobotulinumtoxinA (Xeomin), and 250 U to 1000 U of abobotulinumtoxinA (Dysport).BtA was associated with a moderate-to-large improvement in the participant's baseline clinical status as assessed by investigators, with reduction of 8.06 points in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS total score) at week 4 after injection (95% CI 6.08 to 10.05; I² = 0%) compared to placebo, corresponding on average to a 18.7% improvement from baseline. The mean difference (MD) in TWSTRS pain subscore at week 4 was 2.11 (95% CI 1.38 to 2.83; I² = 0%). Overall, both participants and clinicians reported an improvement of subjective clinical status. There were no differences between groups regarding withdrawals due to adverse events. However, BtA treatment was associated with an increased risk of experiencing an adverse event (risk ratio (RR) 1.19; 95% CI 1.03 to 1.36; I² = 16%). Dysphagia (9%) and diffuse weakness/tiredness (10%) were the most common treatment-related adverse events (dysphagia: RR 3.04; 95% CI 1.68 to 5.50; I² = 0%; diffuse weakness/tiredness: RR 1.78; 95% CI 1.08 to 2.94; I² = 0%). Treatment with BtA was associated with a decreased risk of participants withdrawing from trials. We have moderate certainty in the evidence across all of the aforementioned outcomes.We found no evidence supporting the existence of a clear dose-response relationship with BtA, nor a difference between BtA formulations, nor a difference with use of EMG-guided injection.Due to clinical heterogeneity, we did not pool data regarding health-related quality of life, duration of clinical effect, or the development of secondary non-responsiveness.

AUTHORS' CONCLUSIONS

We have moderate certainty in the evidence that a single BtA treatment session is associated with a significant and clinically relevant reduction of cervical dystonia-specific impairment, including severity, disability, and pain, and that it is well tolerated, when compared with placebo. There is also moderate certainty in the evidence that people treated with BtA are at an increased risk of developing adverse events, most notably dysphagia and diffuse weakness. There are no data from RCTs evaluating the effectiveness and safety of repeated BtA injection cycles. There is no evidence from RCTs to allow us to draw definitive conclusions on the optimal treatment intervals and doses, usefulness of guidance techniques for injection, the impact on quality of life, or the duration of treatment effect.

Botulinum toxin type A versus botulinum toxin type B for cervical dystonia

BACKGROUND

This is an update of a Cochrane review first published in 2003. Cervical dystonia is the most common form of focal dystonia and is a disabling disorder characterised by painful involuntary head posturing. There are two available formulations of botulinum toxin, with botulinum toxin type A (BtA) usually considered the first line therapy for this condition. Botulinum toxin type B (BtB) is an alternative option, with no compelling theoretical reason why it might not be as- or even more effective - than BtA.

OBJECTIVES

To compare the efficacy, safety and tolerability of botulinum toxin type A (BtA) versus botulinum toxin type B (BtB) in people with cervical dystonia.

SEARCH METHODS

To identify studies for this review we searched the Cochrane Movement Disorders Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, reference lists of articles and conference proceedings. All elements of the search, with no language restrictions, were last run in October 2016.

SELECTION CRITERIA

Double-blind, parallel, randomised, placebo-controlled trials (RCTs) comparing BtA versus BtB in adults with cervical dystonia.

DATA COLLECTION AND ANALYSIS

Two independent authors assessed records, selected included studies, extracted data using a paper pro forma, and evaluated the risk of bias. We resolved disagreements by consensus or by consulting a third author. We performed meta-analyses using the random-effects model, for the comparison BtA versus BtB to estimate pooled effects and corresponding 95% confidence intervals (95% CI). No prespecified subgroup analyses were carried out. The primary efficacy outcome was improvement on any validated symptomatic rating scale, and the primary safety outcome was the proportion of participants with adverse events.

MAIN RESULTS

We included three RCTs, all new to this update, of very low to low methodological quality, with a total of 270 participants.Two studies exclusively enrolled participants with a known positive response to BtA treatment. This raises concerns of population enrichment, with a higher probability of benefit from BtA treatment. None of the trials were free of for-profit bias, nor did they provide information regarding registered study protocols. All trials evaluated the effect of a single Bt treatment session, and not repeated treatment sessions, using doses from 100 U to 250 U of BtA (all onabotulinumtoxinA, or Botox, formulations) and 5000 U to 10,000 U of BtB (rimabotulinumtoxinB, or Myobloc/Neurobloc).We found no difference between the two types of botulinum toxin in terms of overall efficacy, with a mean difference of -1.44 (95% CI -3.58 to 0.70) points lower on the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) for BtB-treated participants, measured at two to four weeks after injection. The proportion of participants with adverse events was also not different between BtA and BtB (BtB versus BtA risk ratio (RR) 1.40; 95% CI 1.00 to 1.96). However, when compared to BtA, treatment with BtB was associated with an increased risk of one adverse events of special interest, namely treatment-related sore throat/dry mouth (BtB versus BtA RR of 4.39; 95% CI 2.43 to 7.91). Treatment-related dysphagia (swallowing difficulties) was not different between BtA and BtB (RR 2.89; 95% CI 0.80 to 10.41). The two types of botulinum toxin were otherwise clinically non-distinguishable in all the remaining outcomes.

AUTHORS' CONCLUSIONS

The previous version of this review did not include any trials, since these were still ongoing at the time. Therefore, with this update we are able to change the conclusions of this review. There is low quality evidence that a single treatment session of BtA (specifically onabotulinumtoxinA) and a single treatment session of BtB (rimabotulinumtoxinB) are equally effective and safe in the treatment of adults with certain types of cervical dystonia. Treatment with BtB appears to present an increased risk of sore throat/dry mouth, compared to BtA. Overall, there is no clinical evidence from these single-treatment trials to support or contest the preferential use of one form of botulinum toxin over the other.

Botulinum toxin type B for cervical dystonia

BACKGROUND

This is an update of a Cochrane review first published in 2004, and previously updated in 2009 (no change in conclusions). Cervical dystonia is a frequent and disabling disorder characterised by painful involuntary head posturing. Botulinum toxin type A (BtA) is usually considered the first line therapy for this condition, although botulinum toxin type B (BtB) is an alternative option.

OBJECTIVES

To compare the efficacy, safety and tolerability of botulinum toxin type B (BtB) versus placebo in people with cervical dystonia.

SEARCH METHODS

We identified studies for inclusion in the review using the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, reference lists of articles and conference proceedings, last run in October 2015. We ran the search from 1977 to 2015. The search was unrestricted by language.

SELECTION CRITERIA

Double-blind, parallel, randomised, placebo-controlled trials (RCTs) of BtB versus placebo in adults with cervical dystonia.

DATA COLLECTION AND ANALYSIS

Two independent authors assessed records, selected included studies, extracted data using a paper pro forma and evaluated the risk of bias. We resolved disagreements by consensus or by consulting a third author. We performed one meta-analysis for the comparison BtB versus placebo. We used random-effects models when there was heterogeneity and fixed-effect models when there was no heterogeneity. In addition, we performed pre-specified subgroup analyses according to BtB doses and BtA previous clinical responsiveness. The primary efficacy outcome was overall improvement on any validated symptomatic rating scale. The primary safety outcome was the number of participants with any adverse event.

MAIN RESULTS

We included four RCTs of moderate overall methodological quality, including 441 participants with cervical dystonia. Three studies excluded participants known to have poorer response to Bt treatment, therefore including an enriched population with a higher probability of benefiting from Bt treatment. None of the trials were independently funded. All RCTs evaluated the effect of a single Bt treatment session using doses between 2500 U and 10,000 U. BtB was associated with an improvement of 14.7% (95% CI 9.8% to 19.5) in the patients' baseline clinical status as assessed by investigators, with reduction of 6.8 points in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS-total score) at week 4 after injection (95% CI 4.54 to 9.01). Mean difference (MD) in TWSTRS-pain score at week 4 was 2.20 (95% CI 1.25 to 3.15). Overall, both participants and clinicians reported an improvement of subjective clinical status. There were no differences between groups in the withdrawals rate due to adverse events or in the proportion of participants with adverse events. However, BtB-treated patients had a 7.65 (95% CI 2.75 to 21.32) and a 6.78 (95% CI 2.42 to 19.05) increased risk of treatment-related dry mouth and dysphagia, respectively. Statistical heterogeneity between studies was low to moderate for most outcomes. All tested dosages were efficacious against placebo without clear-cut evidence of a dose-response gradient. However, duration of effect (time until return to baseline TWSTRS-total score) and risk of dry mouth and dysphagia were greater in the subgroup of participants treated with higher BtB doses. Subgroup analysis showed a higher improvement with BtB among BtA-non-responsive participants, although there were no differences in the effect size between the BtA-responsive and non-responsive subgroups.

AUTHORS' CONCLUSIONS

A single BtB-treatment session is associated with a significant and clinically relevant reduction of cervical dystonia impairment including severity, disability and pain, and is well tolerated, when compared with placebo. However, BtB-treated patients are at an increased risk of dry mouth and dysphagia. There are no data from RCTs evaluating the effectiveness and safety of repeated BtB injection cycles. There are no RCT data to allow us to draw definitive conclusions on the optimal treatment intervals and doses, usefulness of guidance techniques for injection, and impact on quality of life.

Animal models for dystonia

Symptomatic animal models have clinical features consistent with human disorders and are often used to identify the anatomical and physiological processes involved in the expression of symptoms and to experimentally demonstrate causality where it would be infeasible in the patient population. Rodent and primate models of dystonia have identified basal ganglia abnormalities, including alterations in striatal GABAergic (ie, transmitting or secreting γ-aminobutyric acid) and dopaminergic transmission. Symptomatic animal models have also established the critical role of the cerebellum in dystonia, particularly abnormal glutamate signaling and aberrant Purkinje cell activity. Further, experiments suggest that the basal ganglia and cerebellum are nodes in an integrated network that is dysfunctional in dystonia. The knowledge gained from experiments in symptomatic animal models may serve as the foundation for the development of novel therapeutic interventions to treat dystonia. © 2013 Movement Disorder Society.

Dystonia as a network disorder: what is the role of the cerebellum?

The dystonias are a group of disorders defined by sustained or intermittent muscle contractions that result in involuntary posturing or repetitive movements. There are many different clinical manifestations and causes. Although they traditionally have been ascribed to dysfunction of the basal ganglia, recent evidence has suggested dysfunction may originate from other regions, particularly the cerebellum. This recent evidence has led to an emerging view that dystonia is a network disorder that involves multiple brain regions. The new network model for the pathogenesis of dystonia has raised many questions, particularly regarding the role of the cerebellum. For example, if dystonia may arise from cerebellar dysfunction, then why are there no cerebellar signs in dystonia? Why are focal cerebellar lesions or degenerative cerebellar disorders more commonly associated with ataxia rather than dystonia? Why is dystonia more commonly associated with basal ganglia lesions rather than cerebellar lesions? Can answers obtained from animals be extrapolated to humans? Is there any evidence that the cerebellum is not involved? Finally, what is the practical value of this new model of pathogenesis for the neuroscientist and clinician? This article explores potential answers to these questions.

Pathologic changes in the brain in cervical dystonia pre- and post-mortem - a commentary with a special focus on the cerebellum

In a recent issue of Experimental Neurology, Prudente et al. (2012) investigated the neuropathology of cervical dystonia in six patients. Their most important finding was a patchy loss of cerebellar Purkinje cells in the cerebellum. In this article we discuss their findings in the context of a review including primary and secondary cervical dystonia. An update is given of the current knowledge on structural and functional brain abnormalities in idiopathic cervical dystonia with a special focus on the cerebellum.

Animal models for drug discovery in dystonia

Dystonia is a neurological disorder characterized by involuntary twisting movements and unnatural postures. There are many different forms of dystonia, which affect over three million people worldwide. Effective treatments are available only for a minority of patients, so new treatments are sorely needed. Several animal species have been used to develop models for different forms of dystonia, each with differing strengths and weaknesses. This review outlines the strategies that have been used to exploit these models for drug discovery. Some have been used to dissect the pathogenesis of dystonia for the identification of molecular targets for intervention. Others have been used for the empirical identification of candidate drugs. Therefore, the animal models provide promising new tools for developing better treatments for dystonia.

Botulinum toxin assessment, intervention and aftercare for cervical dystonia and other causes of hypertonia of the neck: international consensus statement

Dystonia in the neck region can be safely and effectively reduced with injections of Botulinum neurotoxin-A and B. People with idiopathic cervical dystonia have been studied the most. Benefits following injection include increased range of movement at the neck for head turning, decreased pain, and increased functional capacity (Class I evidence, level A recommendation). The evidence for efficacy and safety in patients with secondary dystonia in the neck is unclear based on the lack of rigorous research conducted in this heterogeneous population (level U recommendation). Psychometrically sound assessments and outcome measures exist to guide decision-making (Class I evidence, level A recommendation). Much less is known about the effectiveness of therapy to augment the effects of the injection (Class IV, level U recommendation). More research is needed to answer questions about safety and efficacy in secondary spastic neck dystonia, effective adjunctive therapy, dosing and favourable injection techniques.

International consensus statement for the use of botulinum toxin treatment in adults and children with neurological impairments--introduction

Botulinum neurotoxin (BoNT) is most commonly used to reduce focal over-activity in skeletal muscle, although newer indications such as management of drooling, pain and tremor are emerging. Treatment of spasticity incorporating BoNT is usually part of an integrated multidisciplinary rehabilitation programme. Prior to initiating this therapy, specific functional limitations, goals and expected outcomes of treatment should be discussed with the patient/carers. Muscle selection and the order/priority of treatment should be agreed. Treatment goals may involve increasing active or passive function or the avoidance of secondary complications or impairment progression. This paper describes the basic science mechanisms of the action of BoNT and subsequent nerve recovery and introduces a supplement comprising the best available evidence and expert opinion from international panels on questions of assessment, indications, BoNT regimen, adjunctive therapy, expected outcomes and recommended monitoring. Speciality areas reviewed include Paediatric Lower Limb Hypertonicity, Paediatric Upper Limb Hypertonicity, Adult Lower Limb Hypertonicity, Adult Upper Limb Hypertonicity, Cervical Dystonia, Drooling and Pain and Niche Indications. There is good quality scientific evidence to support the efficacy of BoNT to reduce muscle over-activity in the limbs secondary to central nervous system disorders in adults and children, to address primary or secondary cervical dystonia, to reduce saliva flow and to treat some pain syndromes. There is emergent evidence for the efficacy of BoNT to reduce focal tremor, to treat other types of pain including neuropathic pain and also to improve function following treatment of focal muscle over-activity.

Animal models of dystonia: Lessons from a mutant rat

Dystonia is a motor sign characterized by involuntary muscle contractions which produce abnormal postures. Genetic factors contribute significantly to primary dystonia. In comparison, secondary dystonia can be caused by a wide variety of metabolic, structural, infectious, toxic and inflammatory insults to the nervous system. Although classically ascribed to dysfunction of the basal ganglia, studies of diverse animal models have pointed out that dystonia is a network disorder with important contributions from abnormal olivocerebellar signaling. In particular, work with the dystonic (dt) rat has engendered dramatic paradigm shifts in dystonia research. The dt rat manifests generalized dystonia caused by deficiency of the neuronally restricted protein caytaxin. Electrophysiological and biochemical studies have shown that defects at the climbing fiber-Purkinje cell synapse in the dt rat lead to abnormal bursting firing patterns in the cerebellar nuclei, which increases linearly with postnatal age. In a general sense, the dt rat has shown the scientific and clinical communities that dystonia can arise from dysfunctional cerebellar cortex. Furthermore, work with the dt rat has provided evidence that dystonia (1) is a neurodevelopmental network disorder and (2) can be driven by abnormal cerebellar output. In large part, work with other animal models has expanded upon studies in the dt rat and shown that primary dystonia is a multi-nodal network disorder associated with defective sensorimotor integration. In addition, experiments in genetically engineered models have been used to examine the underlying cellular pathologies that drive primary dystonia. This article is part of a Special Issue entitled "Advances in dystonia".

The effects of reversible inactivation of the subthalamo-pallidal pathway on the behaviour of naive and hemiparkinsonian monkeys

This study was designed to further investigate the role of the subthalamic nucleus (STN) and globus pallidus internus (GPi) in the pathophysiology of Parkinson's disease. The prevailing theory about the pathophysiology of Parkinson's disease (PD) predicts that there is overactivity of the subthalamo-pallidal pathway. In order to inactivate that pathway, naive and hemiparkinsonian monkeys were locally administered either muscimol (to reversibly inactivate the contralateral STN) or kynurenic acid (to reduce glutamatergic activity in the contralateral GPi). Three naive and 2 hemiparkinsonian monkeys were studied. Intra-carotid MPTP was administered to produce 2 hemiparkinsonian monkeys. Injection sites of muscimol and kynurenic acid in the brain were confirmed electrophysiologically and histologically. Injections of muscimol into the STN in naive and hemiparkinsonian monkeys caused reversible contralateral dystonia, but did not alleviate Parkinsonism. Only one kynurenic acid injection into GPi partially alleviated Parkinsonism. On the basis of the results in this study, aspects of the currently accepted hypothesis of the pathophysiology of PD cannot be confirmed. However, this study reports that the STN has an important role in the production of dystonia. This experimental model of dystonia will prove suitable for further study of both the mechanisms causing dystonia as well as for possible therapeutic approaches to its treatment.

Dystonia associated with pontomesencephalic lesions

Secondary dystonia is well known subsequent to lesions of the basal ganglia or the thalamus. There is evidence that brainstem lesions may also be associated with dystonia, but little is known about pathoanatomical correlations. Here, we report on a series of four patients with acquired dystonia following brainstem lesions. There were no basal ganglia or thalamic lesions. Three patients suffered tegmental pontomesencephalic hemorrhage and one patient diffuse axonal injury secondary to severe craniocerebral trauma. Dystonia developed with a delay of 1 to 14 months, at a mean delay of 6 months. The patients' mean age at onset was 33 years (range 4-56 years). All patients presented with hemidystonia combined with cervical dystonia, and two patients had craniofacial dystonia in addition. Three patients had postural or kinetic tremors. Dystonia was persistent in three patients, and improved gradually in one. There was little response to medical treatment. One patient with hemidystonia combined with cervical dystonia improved after thalamotomy. Overall, the phenomenology of secondary dystonia due to pontomesencephalic lesions is similar to that caused by basal ganglia or thalamic lesions. Structures involved include the pontomesencephalic tegmentum and the superior cerebellar peduncles. Such lesions are often associated with fatal outcome. While delayed occurrence of severe brainstem dystonia appears to be rare, it is possible that mild manifestations of dystonia might be ignored or not be emphasized in the presence of other disabling deficits.

Research priorities in spasmodic dysphonia

OBJECTIVE

To identify research priorities to increase understanding of the pathogenesis, diagnosis, and improved treatment of spasmodic dysphonia.

STUDY DESIGN AND SETTING

A multidisciplinary working group was formed that included both scientists and clinicians from multiple disciplines (otolaryngology, neurology, speech pathology, genetics, and neuroscience) to review currently available information on spasmodic dysphonia and to identify research priorities.

RESULTS

Operational definitions for spasmodic dysphonia at different levels of certainty were recommended for diagnosis and recommendations made for a multicenter multidisciplinary validation study.

CONCLUSIONS

The highest priority is to characterize the disorder and identify risk factors that may contribute to its onset. Future research should compare and contrast spasmodic dysphonia with other forms of focal dystonia. Development of animal models is recommended to explore hypotheses related to pathogenesis. Improved understanding of the pathophysiology of spasmodic dysphonia should provide the basis for developing new treatment options and exploratory clinical trials.

SIGNIFICANCE

This document should foster future research to improve the care of patients with this chronic debilitating voice and speech disorder by otolaryngology, neurology, and speech pathology.

Botulinum toxin treatment of axial and cervical dystonia

Axial truncal dystonia is characterized by an abnormal trunk posture often superimposed by myoclonic motor activities. Cervical dystonia is a motor syndrome characterized by abnormal head and neck posture due to tonic involuntary contractions in a certain set of muscles often superimposed by myoclonic or tremulous movements. Intramuscular injection of botulinum toxin is the first line treatment in cervical dystonia, in axial truncal dystonias botulinum toxin therapy is used only in mild forms. In this review the theoretical background, practical aspects and efficacy results especially in cervical dystonia are presented. Treatment of axial trunk dystonia is only briefly discussed at the beginning of this review.

Botulinum toxin type A versus anticholinergics for cervical dystonia

BACKGROUND

Cervical dystonia is the most common form of focal dystonia. It is characterized by involuntary posturing of the head and frequently is associated with neck pain. Disability and social withdrawal are common. Most cases are idiopathic and generally cervical dystonia is a life-long disorder. Botulinum toxin Type A (BtA) is now the first line therapy. Before BtA, anticholinergics were the most widely accepted treatment, so it is important to understand how these two treatments compare.

OBJECTIVES

To compare the clinical efficacy and safety of BtA versus anticholinergic drugs in the treatment of cervical dystonia.

SEARCH STRATEGY

We searched the Cochrane Movement Disorders Group trials register (June 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 2, 2003), MEDLINE 1977 to June 2003), EMBASE (1977 to June 2003) and reference lists of articles. We also contacted manufacturers and researchers in the field.

SELECTION CRITERIA

Randomised studies comparing BtA versus any anticholinergic drug for the treatment of cervical dystonia.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Adverse effects information was collected from the trials.

MAIN RESULTS

We found only one trial suitable for inclusion and accordingly no meta-analysis was performed. It compared BtA versus trihexyphenidyl in 66 patients with cervical dystonia. Although this was a relatively small trial with short duration, the results can probably be generalized for the population, since the trial appears to be unbiased and produced clear clinically significant results. The results favoured BtA, and the difference was similar in size to that obtained in a systematic review comparing BtA with placebo. BtA was better tolerated.

AUTHORS' CONCLUSIONS

The available evidence suggests that BtA injections provide more objective and subjective benefit than trihexyphenidyl to patients with cervical dystonia. We could not draw any conclusions about other anticholinergic drugs. Future trials should explore the role of anticholinergic drugs in patients that do not get benefit with BtA.

Botulinum toxin type A versus botulinum toxin type B for cervical dystonia

BACKGROUND

Cervical dystonia is the most common form of focal dystonia. It is characterized by involuntary posturing of the head and frequently is associated with neck pain. Disability and social withdrawal are common. Most cases are idiopathic, and generally it is a life-long disorder. In recent years, botulinum toxin type A (BtA) has become first line therapy for cervical dystonia. However, not all patients respond well to BtA, and 5 to 10% become resistant to it. Botulinum toxin B (BtB) is an alternative to BtA and offers the potential to help patients who do not respond to BtA. At present there is no compelling theoretical reason why it should not be as effective as, or even more effective than, BtA.

OBJECTIVES

To compare the clinical efficacy and safety of BtA versus BtB in cervical dystonia.

SEARCH STRATEGY

Studies for inclusion in the review were identified using the Cochrane Movement Disorders Group trials register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, by handsearching the Movement Disorders Journal and abstracts of international congresses on movement disorders and botulinum toxin, by communication with other researchers in the field, by searching reference lists of papers found using the above search strategies, and by contact with authors and drug manufacturer.

SELECTION CRITERIA

Studies were considered eligible for inclusion in the review if they evaluated the efficacy of BtA versus BtB for the treatment of cervical dystonia. Trials must have been randomised and placebo-controlled.

DATA COLLECTION AND ANALYSIS

A paper pro-forma was used to collect data from the included studies using double extraction by two independent reviewers. Each trial was assessed for internal validity by each of the two reviewers. Differences were settled by discussion. The outcome measures used included improvement in symptomatic rating scales, subjective evaluation by patients and clinicians, changes in pain scores, changes in quality of life assessments, and frequency and severity of adverse events.

MAIN RESULTS

We cannot give any results since we have only identified two ongoing trials and there are no preliminary results or interim analyses available for them. The full results of these trials are expected in late 2004 or 2005.

AUTHORS' CONCLUSIONS

It is currently not possible to make definitive comparisons between BtA and BtB for the treatment of cervical dystonia; uncontrolled comparisons should be regarded with suspicion.

Botulinum toxin type A therapy for cervical dystonia

BACKGROUND

Cervical dystonia is characterized by involuntary posturing of the head and frequently is associated with neck pain. Disability and social withdrawal are common. In recent years, Botulinum toxin Type A (BtA) has become the first line therapy. However its true efficacy, in particular the potential effect size, is still unclear.

OBJECTIVES

To determine whether botulinum toxin (BtA) is an effective and safe treatment for cervical dystonia.

SEARCH STRATEGY

We searched the Cochrane Movement Disorders Group trials register (June 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2003, MEDLINE (1977 to June 2003), EMBASE (1977 to June 2003) and reference lists of articles. We also contacted drug manufacturers and researchers in the field.

SELECTION CRITERIA

Randomised studies comparing BtA with placebo in adults with cervical dystonia.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Adverse effects information was collected from the trials.

MAIN RESULTS

We found thirteen high quality eligible studies. They were short term (6 to 16 weeks). Eight trials, enrolling 361 patients, used the BtA formulation Botox(r) and five, enrolling 319 patients, used the BtA formulation Dysport. The dose and technique of administration varied significantly between studies.Meta-analysis showed statistically and clinically significant improvements on objective rating scales: (Peto OR 4.31; 95% confidence interval (CI) 2.68 to 6.94) and subjective rating scales (Peto OR 6.58; 95% CI 4.55 to 9.54); and for pain relief in subjective scales (Peto OR 11.92; 95% CI 6.32 to 22.5). However, for many of the outcomes, we could use data from only a few studies. Only adverse events clearly associated with the mechanism of action of BtA were more frequent in the treatment group. These included neck weakness, dysphagia, dry mouth/sore throat and voice changes/hoarseness. Sub-group and sensitivity analyses showed a clear dose-response relationship for subjective and objective benefit and for frequency and severity of adverse events. Indirect comparisons between trials that used Dysport against placebo and trials that used Botox against placebo showed no significant differences between Dysport and Botox in terms of benefits or adverse events.

AUTHORS' CONCLUSIONS

A single injection cycle of BtA is effective and safe for treating cervical dystonia. Enriched trials (using patients previously treated with BtA), suggest that further injection cycles continue to work for most patients.

Botulinum toxin type B for cervical dystonia

BACKGROUND

Cervical dystonia is the most common form of focal dystonia. It is characterized by involuntary posturing of the head and frequently is associated with neck pain. Disability and social withdrawal are common. Most cases of cervical dystonia are idiopathic and generally it is a life-long disorder. In recent years, Botulinum toxin type A (BtA) has become the first line therapy. However, some patients become resistant to it. This problem led to the study of another Botulinum toxin (Bt) serotype, Bt type B (BtB) to address the issues of clinical efficacy, effect size, and safety of BtB in the treatment of cervical dystonia.

OBJECTIVES

To determine whether botulinum toxin (BtB) is an effective and safe treatment for cervical dystonia.

SEARCH STRATEGY

We identified studies for inclusion in the review using the Cochrane Movement Disorders Group trials register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE; and by handsearching the Movement Disorders Journal and abstracts of international congresses on movement disorders and botulinum toxin, by communication with other researchers in the field, by searching reference lists of papers found using the above search strategies, and by contacting authors and drug manufacturers.

SELECTION CRITERIA

We considered studies eligible for inclusion in the review if they evaluated the efficacy of BtB for the treatment of cervical dystonia in randomized, placebo-controlled trials.

DATA COLLECTION AND ANALYSIS

We used a paper pro forma to collect data from the included studies with double extraction by two independent reviewers. Both reviewers assessed each trial for internal validity and settled differences by discussion. The outcome measures used included adverse events, improvement in symptomatic rating scales, subjective evaluation by patients and clinicians, changes in pain scores, changes in quality of life assessments.

MAIN RESULTS

Studies were short term (16 weeks) employing a single BtB injection session. All were multicentre and conducted in the US. All patients included had previously received BtA. The trials differed with respect to whether or not the patients were still responding to BtA but other entry criteria were similar. All studies used a dose of 10,000 Units of BtB in one group and the technique of administration was the same. Meta-analysis of three trials enrolling 308 participants showed statistically and clinically significant improvements in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score at week four with a Peto odds ratio (OR) for the number of patients who had at least a 20% improvement of 4.69 (95% CI 2.06 to 10.69) and a weighted mean difference of -5.92 (95% CI -9.61 to -2.23). Subjective rating scales (Patient Global Assessment of Change, Investigator Global Assessment of Change, and Patient Analog Pain Assessment) also improved. Adverse events clearly associated with the mechanism of action of BtB included dysphagia and dry mouth and the number of patients with any adverse event were more frequent in BtB treatment groups. Subgroup analyses showed a clear dose-response relationship for subjective and objective benefit, for frequency and severity of adverse events, and a greater benefit for BtA resistant patients than BtA responders in the primary outcome. The duration of effect was about 16 weeks. We found three eligible studies enrolling 308 participants. Studies were short term (16 weeks) employing a single BtB injection session. All were multicentre and conducted in the US. All patients included had previously received BtA. The trials differed with respect to whether or not the patients were still responding to BtA but other entry criteria were similar. Patient groups were appropriately selected and well matched. From the methodological point of view these trials were probably not subjected to important selection, performance or attrition bias and all studies used an intention-to-treat analysis.The dose varied significantly between studies although all used 10,000 Units of BtB in one group and the technique of administration was the same. The primary outcome in all trials was change in TWSTRS total score at week four and other efficacy outcomes were similar between studies. The number of dropouts was small and balanced in all trials. Reasons for withdrawals were given. One randomized double-blind placebo-controlled study was excluded because data couldn't be extracted for the outcomes. Meta-analysis showed statistically and clinically significant improvements with a Peto odds ratio (OR) of 20% in TWSTRS total score at week four (OR 4.69; 95% CI 2.06 to 10.69) and a weighted mean difference of -5.92 (95% CI -9.61 to -2.23). Subjective rating scales (Patient Global Assessment of Change, Investigator Global Assessment of Change, and Patient Analog Pain Assessment) also improved. The weighted mean difference for changes in these subjective scales varied between -13% to -21%. However, for many of the outcomes, we could not combine data from all studies. Only adverse events clearly associated with the mechanism of action of BtB were more frequent in the treatment group. These included dysphagia and dry mouth. The number of patients with any adverse event was more frequent with BtB. Subgroup analyses showed a clear dose-response relationship for subjective and objective benefit and for frequency and severity of adverse events. Subgroup analyses showed a greater benefit for the BtA resistant patients than BtA responders in the primary outcome. The duration of effect was about 16 weeks. These trials did not measure quality of life nor did they establish the long term duration of effect or immunogenicity

AUTHORS' CONCLUSIONS

A single injection of BtB was effective and safe for treating cervical dystonia. Long-term uncontrolled studies suggested that further injection cycles continue to work for most patients. Future research should explore technical factors such as the optimum treatment intervals and use of image or electromyographic guidance for administration. Other issues include service delivery, quality of life, long-term efficacy and safety, and the relative indications for BtA, BtB and other treatments such as deep brain stimulation.

Secondary cervical dystonia associated with structural lesions of the central nervous system

We tested the hypothesis that structural lesions of the central nervous system (CNS) associated with cervical dystonia more commonly involve the cerebellum and its primary afferent pathways than basal ganglia structures. Cervical dystonia is the most common focal dystonia, the majority of cases are idiopathic, and only a small percentage of patients have a family history of dystonia or other movement disorders. Pathophysiological mechanisms operative in solely or predominantly appendicular dystonias such as writer's cramp and Oppenheim's dystonia, respectively, may not be directly applicable to axial dystonias. The localization of structural lesions of the CNS associated with secondary cervical dystonia may provide some insight into the neural structures potentially involved in primary cervical dystonia. The National Library of Medicine Gateway (from 1960) and a clinical database maintained by the senior author (from 1999) were searched for cases of secondary cervical dystonia associated with structural lesions of the CNS. Search terms included one or more of the following: dystonia, torticollis, cervical, secondary, and symptomatic. Lesion localization and type, patient age, patient gender, head position, occurrence of sensory tricks, and associated neurological findings were tabulated for each case. Structural lesions associated with cervical dystonia were most commonly localized to the brainstem and cerebellum. The remaining cases were equally divided between the cervical spinal cord and basal ganglia. Although inconsistent, head rotation tended to be contralateral to lesion localization. Additional neurological abnormalities were present in the majority of patients with secondary cervical dystonia. The relative paucity of basal ganglia pathology and concentration of lesions in the brainstem, cerebellum, and cervical spinal cord in patients with secondary cervical dystonia suggests that dysfunction of cerebellar afferent pathways may be important to the pathophysiology of primary cervical dystonia.

Dystonia after striatopallidal and thalamic stroke: clinicoradiological correlations and pathophysiological mechanisms

OBJECTIVE

To establish the pathophysiological mechanisms of striatopallidal and thalamic dystonia.

METHODS

Five patients from among 26 who presented (between March 1987 and July 1996) with focal dystonia, segmental dystonia, or hemidystonia caused by a single localised vascular lesion, were selected. Patients with lesions with indefinite boundaries, and diffuse, or multiple, or large brain lesions were excluded. Three dimensional T1 weighted MRI (1.5 tesla) was performed to determine the topography of the lesions. The atlas of Hassler allowed the stereotactic localisation of the lesions to be specified exactly.

RESULTS

Three patients had dystonic spasms associated with striatopallidal lesions and one with a thalamic and striatopallidal lesion. One other patient presented with a myoclonic dystonia related to a thalamic lesion. The striatopallidal lesions were located in the sensorimotor area with a somatotopical distribution. The pure thalamic lesion involved the centromedian nucleus, the sensory nuclei, and the pulvinar whereas the thalamic and striatopallidal lesion was located in the pallidonigral thalamic territory, which receives pallidonigral inputs.

CONCLUSION

The striatopallidal dystonia might be the consequence of the interruption of the cortico-striato-pallido-thalamo-cortical loop induced by lesions located within the sensorimotor part of the striatopallidal complex. By contrast, it is suggested that thalamic dystonia might be caused by lesions located in the centro-median or the ventral intermediate nuclei, outside the pallidonigral territory, but leading also to a dysfunction of the cortico-striato-pallido-thalamo-cortical loop.

Cervical dystonia associated with tumors of the posterior fossa

Cervical dystonia was associated with posterior fossa tumors in three patients. The onset of dystonia paralleled the appearance of other focal neurologic signs. All patients had extraaxial tumors located in the cerebellopontine angle that were removed via suboccipital approaches. The tumors were identified as schwannomas arising from the glossopharyngeal nerve and from the vagus/accessory nerves; and a meningioma. Postoperatively, the cervical dystonia improved markedly during a period of 8 years in one patient, and it remitted completely within 1 year in another patient. In the third patient, cervical dystonia persisted. The combination of the clinical findings and the temporal relationship of their appearance suggest a causal association between the posterior fossa tumors and cervical dystonia in three cases. Possible pathogenic mechanisms are reviewed.

Cervical dystonia due to spinal cord ependymoma: involvement of cervical cord segments in the pathogenesis of dystonia

We report a patient with a progressive motor disorder dominated by pyramidal signs in all four extremities and cervical dystonia in the form of torticollis, who had imaging features of cervical cord tumor on magnetic resonance imaging (MRI) scanning. Ependymoma was the final diagnosis by histology. Cervical dystonia presenting as a manifestation of an identified focal central nervous system (CNS) lesion is infrequent. We believe our patient to be the first adult example of cervical cord tumor giving rise to cervical dystonia. Adding this entity to the list of differential diagnosis of torticollis is considered, and its mechanisms are discussed.

Microvascular decompression for spasmodic torticollis

Twenty patients with spasmodic torticollis (ST) were treated by microvascular decompression (MVD) of the spinal accessory nerves, the upper cervical nerve roots and the brainstem. Thirteen were female and seven male. Median age was 47 years (range 39 to 70 years). Median duration of symptoms was 5 years (range 4 months to 17 years). Ten had right horizontal; nine, left horizontal; and one, retrocollis ST. Twenty-two operations were performed on twenty patients, suboccipital craniectomy and C1 laminectomy in 18 and retromastoid craniectomy in 4 operations. The most common compressing blood vessels were the vertebral artery and/or the posterior inferior cerebellar artery. No nerve section was performed. Three patients died of unrelated conditions, 3, 5 1/2, and 6 years postoperatively, respectively. Minimum follow-up period in the rest of the cases is 5 years (range 5 to 10 years). Thirteen (65%) were cured, four (20%) improved with minimal spasm, one (5%) improved with moderate spasm, and two (10%) improved minimally or unchanged. In most cases the cure or improvement was noticed gradually over 6 months to two years following the operation. There was no operative mortality. Postoperative morbidities included transient cerebrospinal fluid leakage through the surgical incision in one case and an apparent multiple small vessel stroke involving periventricular white matter in one reoperation case with full recovery. MVD for ST is a nondestructive benign procedure with high probability of cure or significant improvement.

Acquired torticollis as the only presenting symptom in children with posterior fossa tumors

Acquired torticollis is a symptom of an underlying disorder. It requires a thorough, meticulous search for the cause, because some of the problems associated with torticollis, such as posterior fossa tumor, can be life-threatening.

Swallowing, speech, and brainstem auditory-evoked potentials in spasmodic torticollis

To explore the controversial "brainstem theory" of spasmodic torticollis, eight consecutively referred patients were examined. Three independent examinations were conducted on the same day: a videofluoroscopic barium swallowing examination, an instrumental speech examination, and a brainstem auditory-evoked potential (BAEP) analysis. Swallowing was normal in two patients; speech physiology, in five; and BAEPs, in all. Normal BAEPs refute the brainstem theory, while abnormalities of speech and swallowing temper this conclusion. Several alternative explanations are proposed.

Dystonia following head trauma: a report of nine patients and review of the literature

We report nine patients who developed dystonia following head trauma. The most frequent form was hemidystonia only (six patients). One patient presented with hemidystonia plus torticollis, one with bilateral hemidystonia and one with torticollis only. Seven patients sustained a severe head injury, and two had a mild head injury. At the time of injury, six were younger than 10 years, two were adolescents, and the patient with torticollis only was an adult. Except in the patient with torticollis only, the onset of dystonia varied considerably from months to years. All patients with hemidystonia had posthemiplegic dystonia of delayed onset. Seven out of 8 patients with hemidystonia had lesions involving the contralateral caudate or putamen, as demonstrated by CT and MR. The patient with hemidystonia plus torticollis had no lesion to the basal ganglia, but a contralateral pontomesencephalic lesion. Response to medical treatment was generally poor. Functional stereotactic operations were performed in seven patients. A variety of factors may be responsible for the vascular or nonvascular posttraumatic basal ganglia lesions, which may lead to dystonia. The pathophysiology seems to be more complex than thought previously. We believe that dystonia following head injury is not as rare as is assumed. Awareness of its characteristics and optimized diagnostic procedures will lead to wider recognition of this entity.

Behavior therapy for spasmodic torticollis: a case study suggesting a causal role for anxiety

A 29-year old male with an 8-month history of spasmodic torticollis was treated after three baseline assessments with progressive relaxation, positive practice, and visual feedback. Subjective, behavioral, and physiological (EMG) data indicated that EMG declined across baseline assessments and treatment, while substantial changes in subjective and behavioral data occurred with treatment. Improvement on all dependent measures also was found at a 2-year follow-up. The data are discussed in terms of the non-specific effects of treatment, and the utility and economy of these primarily self-administered procedures.

Spasmodic torticollis--review of 220 patients

220 patients with isolated and idiopathic spasmodic torticollis were followed and treated over a 14 year period. Each patient was given a short questionnaire leading to the present retrospective data analysis. In most areas, including female preponderance and frequency of postural tremor, the findings confirmed previous studies and highlighted particular points: importance of psychopathological antecedents and association with stressful life-events. The discussion deals with some of the conflicting debates surrounding this unusual disorder. What is the role of psychopathological factors? What is the therapeutic prognosis? The best therapeutic results were obtained by combining anticholinergic drugs, local injections and rehabilitation.

[Spasmodic torticollis and frontal meningioma]

A 57 year-old man developed a spasmodic torticollis with involuntary deviation of the head to the right-side. He had a left paramedian frontal meningioma. The association of spasmodic torticollis and other movement disorders has been reported with contralateral lesions in the basal ganglia. Its occurrence in association to a frontal lesion appears to be much less frequent suggesting a possible disorder of frontostriatal connections.

Saccadic function in spasmodic torticollis

Twelve patients with idiopathic spasmodic torticollis were compared with 19 normal controls on tests of saccadic eye movements thought to depend upon normal basal ganglia function. The patients were able to make random, predictive, remembered, and self-paced saccades equally as well as control subjects. This suggests that those parts of the basal ganglia which may be damaged in spasmodic torticollis, are separate from pathways responsible for the normal initiation and execution of saccades.

Spasmodic torticollis due to a midbrain lesion in a case of multiple sclerosis

A case of multiple sclerosis is described in which spasmodic torticollis occurred abruptly and abated after 1 year. Magnetic resonance imaging (MRI) demonstrated a lesion in the mesencephalon. Other symptoms and physical signs that developed at the same time as the spasmodic torticollis were compatible with the lesion that had not been present on MRI 18 months previously. There are very few reports of spasmodic torticollis due to an identified focal lesion; there is evidence from experimental work on animals that midbrain lesions may cause spasmodic torticollis but there has been no previous human example.

Vestibulo-ocular abnormalities in spasmodic torticollis before and after botulinum toxin injections

In order to establish whether vestibular abnormalities often found in spasmodic torticollis are secondary to the abnormal head posture, the vestibulo-ocular reflex (VOR) was studied in eight patients before and after correction of head posture with botulinum toxin. Eye movements were recorded in the dark during sinusoidal and velocity step rotation. Four patients showed a significantly asymmetric response, with the slow phase of the VOR more active ipsilateral to the torticollis (chin). Despite significant improvement of the head posture in all patients for up to 10 weeks following treatment, no correction of the vestibular asymmetry occurred. This suggests that the VOR abnormalities are not caused by the head posture itself. We interpret the findings as evidence of primary involvement of the vestibular system in torticollis and we postulate a widespread derangement of the sensory-motor mechanisms controlling head posture in this disease.

Neurochemical findings in neuroacanthocytosis

We performed a neurochemical study of the brain of two unrelated patients, living in different continents, with neuroacanthocytosis. The levels of monoamines and their metabolites, gamma-aminobutyric acid and substance P, were measured in several brain areas and the monoamine metabolites in cerebrospinal fluid. The binding of 3H-spiperone to striatal membranes and to lymphocytes was also measured. Both patients had a progressive neurological disorder with onset in the third decade of life and characterized by a complex movement disorder, epilepsy, muscular wasting, and changes in behavior. The movement disorder initially manifested with oromandibular dystonia and limb chorea, but at the time of death was characterized by a severe dystonic syndrome. The chemical changes were similar in the two patients. The most important neurochemical findings were a depletion of dopamine and its metabolites in most brain areas, most notably in the striatum, and elevation of norepinephrine levels in the putamen and globus pallidus. Substance P was markedly reduced in the striatum and substantia nigra. Our findings may provide clues to the neurochemical mechanisms underlying dystonia.

Pathological report of four patients presenting with cranial dystonias

Secondary dystonias and experimental models of dystonia suggest that mechanisms responsible for primary dystonias may lie in the basal ganglia or brainstem. A histological study has been done in three patients with cranial dystonia (blepharospasm with oromandibular dystonia in two, blepharospasm alone in one), and one patient with craniocervical dystonia (oromandibular dystonia with retrocollis). In the patient with blepharospasm alone, an angioma, 0.5 mm in diameter, was found in the dorsal pons at the site of the central tegmental tract, confirming that some patients presenting with primary dystonias may have longstanding lesions in the brainstem. In the three other cases, the striatum, pallidum, thalamus, and brainstem were examined and cell populations in the putamen, substantia nigra, and inferior olives were compared with age-matched controls, but no significant abnormality was found.

Spasmodic torticollis relieved by removal of a cervical foreign body

Images

Brain neurotransmitters in dystonia musculorum deformans

We examined histologically and biochemically the brains of two patients with generalized childhood-onset dystonia musculorum deformans. We found no important histologic changes in the basal ganglia, cerebral cortex, higher brain-stem nuclei, locus ceruleus, or raphe nuclei. Similarly, the activity of choline acetyltransferase and the levels of gamma-aminobutyric acid and glutamic acid in the cerebral cortex and basal ganglia were within the control range. In contrast, the norepinephrine concentrations were markedly and consistently decreased in the lateral and posterior hypothalamus, mamillary body, subthalamic nucleus, and locus ceruleus. The serotonin level was subnormal in the dorsal raphe nucleus, as was the dopamine level in the nucleus accumbens and, in one of the two cases, in the striatum. Elevated concentrations of norepinephrine were found in the septum, thalamus, colliculi, red nucleus, and dorsal raphe nucleus; of serotonin, in the globus pallidus, subthalamic nucleus, and locus ceruleus; and of 5-hydroxyindoleacetic acid, in the globus pallidus, subthalamic nucleus, and nuclei raphe centralis inferior and obscurus. The level of homovanillic acid showed little consistent change in the regions examined. We conclude that some of these monoamine changes, especially the pronounced apparent disturbance of noradrenergic brain mechanisms, may represent a basic neurochemical abnormality in dystonia musculorum deformans and may thus be relevant to the pathoneurophysiology and treatment of this disorder.

Management of spasmodic torticollis

Based on a review of the literature, the management of spasmodic torticollis may begin with the conservative measures of pharmacotherapy, sensory feedback, or percutaneous dorsal column stimulation. Approximately 50% of patients will benefit from an adequate trial of these modalities. With particularly resistant and disabling torticollis, the ablative procedures of microsurgical cervical rhizotomy or stereotaxic thalamotomy have offered significant relief in about 74% and 56%, respectively, of properly selected cases. Nevertheless, the variability in the duration of response to all forms of therapy has made the treatment of spasmodic torticollis a difficult and often frustrating undertaking.

Unit activity related to head and eye movements in central thalamus of cats

Single-unit activity was recorded with stereotaxically guided microelectrodes in the central thalamus of five alert cats. The animals were studied with the head either fixed or free to move in a horizontal plane. They were trained to make eye and/or head movements toward discrete visual targets presented on a screen. Unit activity was analyzed in relation to triggered and spontaneous gaze displacements with head fixed and free successively. Four groups of cells were found, all within the thalamic internal medullary lamina: 20 cells were active with eye but not head movements, 49 with head but not eye movements, 36 with head or eye movements, and 17 responding to visual stimuli in the absence of movement. The patterns of firing during gaze shifts are described. It is hypothesized that eye- or head-related units carry a signal representing gaze driving.

Spasmodic torticollis: a behavioral perspective

The literature on spasmodic torticollis is critically reviewed. The currently most popular etiological hypothesis characterizes torticollis as an extrapyramidal disorder, the symptoms of which are aggravated by stress, but there is no unequivocal evidence available to support this view. Psychological mechanisms have been suggested but not elaborated or tested in any detail. A wide range of treatments has been advocated but controlled studies have not been reported, and the problems of assessing outcome have never been tackled adequately. Behavioral treatments have been evaluated more rigorously than other approaches (particularly EMG feedback training), and the literature suggests that they benefit some patients. It is argued that psychologists have the potential for making a very significant contribution to the understanding and management of torticollis. In discussing outcome measures, the more promising techniques that have been used are summarized and a list is presented of the factors which must be considered when assessing torticollis symptoms. Directions for future research are outlined and priorities suggested.