A long-term follow-up of botulinum toxin A in cervical dystonia

Long-term follow-up of intravesical abobotulinumtoxinA (Dysport®) injections in women with idiopathic detrusor overactivity

Objective

Only a few numbers of studies have been published on the use of abobotulinumtoxinA (Dysport®) in idiopathic detrusor overactivity (IDO). This study reported the long-term follow-up of women with IDO who were treated with intravesical Dysport® injections.

Methods

Two hundred and thirty-six patients with IDO who had failed first-line conservative and antimuscarinic therapy received 500-900 units of Dysport® between April 2014 and July 2015. All patients were followed up for 5 years after their initial injection and interviewed on the phone.

Results

A total of 236 women with IDO aged from 18 years to 84 years (mean±standard deviation: 49.6±15.9 years) were included in our study. The median follow-up time for patients was 36.5 (range: 10-70) months, and the median recovery time after injection was 18.5 (range: 0-70) months. A total of 83 (35.2%) patients stated that they had subjective improvement of their symptoms whereas 84 (35.6%) patients did not report any improvement in symptoms. The initial International Consultation on Incontinence Questionnaire Overactive Bladder mean score was 6.9 (standard deviation 3.4). There was a positive association between the median recovery time and the components of the International Consultation on Incontinence Questionnaire Overactive Bladder questionnaire.

Conclusion

In a sub-population of overactive bladder patients with IDO who have failed first-line therapy, a single intravesical Dysport® injection can resolve patient symptoms completely or reduce the symptoms to an acceptable level that can be controlled with antimuscarinics or re-injection on demands.

Efficacy and safety of long-term botulinum toxin treatment for acquired cervical dystonia: a 25-year follow-up

Botulinum toxin A (BoNT/A) is the first-line treatment for idiopathic cervical dystonia (ICD) and is widely used in the clinical setting. To date, scanty data are available on the effectiveness of BoNT in treating acquired cervical dystonia (ACD). Here we present a long-term follow-up of ACD patients treated with BoNT/A that focused on safety and efficacy. The study included subjects who had received at least six treatments of three commercially available BoNT/A drugs [abobotulinumtoxinA (A/Abo), incobotulinumtoxinA (A/Inco) and onabotulinumtoxinA (A/Ona)]. Safety and efficacy were assessed based on patients' self-reports regarding adverse effects (AE), duration of improvement of dystonia and/or pain relief. Global clinical improvement was measured on a six-point scale. 23 patients with ACD were administered 739 treatments (A/Abo in 235, A/Inco in 72, A/Ona in 432) with a mean number of treatments of 31 ± 20 (range 6-76) and duration of 10 ± 6 weeks (range 2-25). The mean dose was 737 ± 292 U for A/Abo, 138 ± 108 U for A/Inco and 158 ± 80 U for A/Ona. The average benefit duration was 89 ± 26 (A/Abo), 88 ± 30 days (A/Inco), and 99 ± 55 days (A/Ona) (p = 0.011); global clinical improvement for all sessions was 4 ± 1. ANOVA one-way analysis indicated that A/Ona had the best profile in terms of duration (p < 0.05), whereas A/Abo had the best pain relief effect (p = 0.002). Side effects were reported in 9% of treatments (67/739), with ten treatments (1%) complicated by two side effects. Most side effects were rated mild to moderate; severe side effects occurred following three treatments with the three different BoNT; two required medical intervention. No allergic reactions were reported. Even after 25 years of repeated treatments, all serotypes of BoNT demonstrate positive effects in treating ACD with long-lasting efficacy and safety.

The Use of High Initial Doses of Botulinum Toxin Therapy for Cervical Dystonia Is a Risk Factor for Neutralizing Antibody Formation-A Monocentric Cross-Sectional Pilot Study

Background and Objectives: The present study aims to analyze the complex patient/treating physician interaction at onset of botulinum toxin (BoNT) therapy in patients with idiopathic cervical dystonia (CD) and the influence of high initial doses on long-term outcomes. Materials and Methods: A total of 74 CD patients with well-documented courses of BoNT treatment were consecutively recruited after written informed consent. Patients had to rate the amount of improvement of CD in percent of severity of CD at onset of BoNT therapy. They had to draw the course of disease severity (CoD) of CD from the onset of symptoms until the onset of BoNT therapy and from the onset of BoNT therapy until recruitment. The remaining severity of CD was estimated by the treating physician using the TSUI score. Demographic- and treatment-related data were extracted from the charts of the patients. Seventeen patients with suspected secondary treatment failure (STF) were tested for the presence of antibodies. Results: Depending on the CoD before BoNT therapy, three patient subgroups could be distinguished: rapid onset, continuous onset and delayed onset groups. Time to BoNT therapy, increase in dose and improvement were significantly different between these three groups. In the rapid onset group, with the highest initial doses, the best improvement was reported, but the highest number of patients with an STF and with neutralizing antibodies was also observed. Conclusion: The use of high initial doses in the BoNT therapy of CD is associated with a rapid response and quick success; however, it leads to an elevated risk for the development of a secondary treatment failure and induction of neutralizing antibodies.

Immunogenicity to Botulinum Toxin Type A: A Systematic Review With Meta-Analysis Across Therapeutic Indications

BACKGROUND

Botulinum toxin A (BTX-A) is commonly employed as a neuromodulator in several neurological diseases and aesthetic indications. Formation of neutralizing antibodies (NAbs) after BTX-A injections may be responsible for treatment failure.

OBJECTIVES

The authors sought to quantify the prevalence of NAbs following treatment with Abobotulinumtoxin A, Incobotulinumtoxin A, and Onabotulinumtoxin A for therapeutic indications.

METHODS

An electronic systematic search (2000-2020) of PubMed, Scopus, Web of Science, and Embase was conducted. Original studies reporting prevalence of NAbs were included. Data analysis was carried out through open meta-analysis softwares.

RESULTS

Forty-three studies involving 8833 patients were included in this meta-analysis. The incidence of NAbs was 1.8% (summary estimate = 0.018, 95% CI [0.012, 0.023]); a meta-regression analysis revealed that BTX-A duration was significantly associated with increased incidence of NAbs (P = 0.007). Patients with dystonia had the highest incidence (7.4%) of NAbs against BTX-A (summary estimate = 0.074, 95% CI = [0.045, 0.103], I2 = 93.%, P < 0.00) followed by patients with spasticity (6.7%) and urological indications (6.2%). Abobotulinumtoxin A was associated with the highest incidence of NAbs (7.4%) (summary estimate = 0.074, 95% CI = [0.053, 0.096], I2 = 97.24%, P < 0.00) by the Incobotulinumtoxin A and Onabotulinumtoxin A 0.3% (summary estimate <0.003%, 95% CI = [-0.001, 0.007], P < 0.003).

CONCLUSIONS

Although the overall incidence of NAbs following BTX-A injections is relatively low, patients with secondary nonresponse to BTX-A with no apparent causes should be investigated for NAbs. A consensus needs to be developed for the optimal management of such patients.

LEVEL OF EVIDENCE: 2

Long-term efficacy and safety of botulinum toxin treatment for cervical dystonia: a critical reappraisal

Introduction: Botulinum toxin (BoNT) injections represent the gold standard treatment for cervical dystonia (CD). Different types of BoNT have been used for the treatment of CD, but only two serotypes, BoNT type A (BoNT-A) and type B (BoNT-B), have been approved by regulatory agencies. Efficacy and safety of BoNT have been well documented by many short-term studies, but the longterm effects have been investigated only relatively recently.Areas covered: In the present review, we aimed to critically reappraise the existing evidence on the long-term efficacy and safety of BoNT treatment in CD. The examined studies mainly explored BoNT-A serotypes. Only a few studies examined the long-term effects of BoNT-B serotypes, and only one head-to-head comparison between BoNT-A and BoNT-B was found. BoNT was consistently reported to be an effective and safe treatment for CD patients, with good outcomes and a few adverse events in the long-term. However about a third of patients still drop out from the treatment during a long-term follow-up.Expert opinion: We conclude that BoNT is safe and effective in the long-term treatment of patients with CD. Additional studies are needed to further explore patients real-life experiences and perspectives to better understand the long-term outcomes and reasons for discontinuation of treatment.

Botulinum Toxin in Movement Disorders: An Update

Since its initial approval in 1989 by the US Food and Drug Administration for the treatment of blepharospasm and other facial spasms, botulinum toxin (BoNT) has evolved into a therapeutic modality for a variety of neurological and non-neurological disorders. With respect to neurologic movement disorders, BoNT has been reported to be effective for the treatment of dystonia, bruxism, tremors, tics, myoclonus, restless legs syndrome, tardive dyskinesia, and a variety of symptoms associated with Parkinson’s disease. More recently, research with BoNT has expanded beyond its use as a powerful muscle relaxant and a peripherally active drug to its potential central nervous system applications in the treatment of neurodegenerative disorders. Although BoNT is the most potent biologic toxin, when it is administered by knowledgeable and experienced clinicians, it is one of the safest therapeutic agents in clinical use. The primary aim of this article is to provide an update on recent advances in BoNT research with a focus on novel applications in the treatment of movement disorders. This comprehensive review of the literature provides a critical review of evidence-based clinical trials and highlights recent innovative pilot studies.

Targeting pain in the long-term treatment of cervical dystonia with botulinum toxin A

AIMS

Cervical pain is one of the most common non-motor symptoms of cervical dystonia (CD) and affects from 54.6% to 88.9% of patients. To date, minority of studies investigated the relevance of pain in a long-term botulinum toxin (BoNT) therapy of CD. The aim of the study was to define an impact of cervical pain on the disease severity and disability, as well as to assess antinociceptive BoNT efficacy in a long-term treatment of CD.

MATERIALS AND METHODS

In this case-control study, CD patients who received stable doses of BoNT for at least 3 years were assessed with the use of validated scales. Participants were divided into two groups depending on the occurrence of CD-related pain.

RESULTS

We examined 50 participants who received a mean of 24 injection cycles (6-51) of BoNT during a mean treatment period of 10.3 years (3.0-23.5). Participants with cervical pain (68.0%) were characterized by higher scores in all scales used in this study: TWSTRS severity (p = 0.030), disability (p < 0.001), total (p < 0.001) and TSUI score (p = 0.046). Pain reduction following BoNT injection lasted longer than muscle relaxation in 85.3% of patients. Pain improvement between first and last BoNT injection cycle was reported by 76.5% of patients with CD-related pain.

CONCLUSIONS

The presence of cervical pain in CD may increase the severity of muscular symptoms and disease-related disability. BoNT has a noticeable antinociceptive effect in the long-term treatment of CD.

Disease Progression of Idiopathic Cervical Dystonia in Spite of Improvement After Botulinum Toxin Therapy

Aim of the Study: To demonstrate general progression of symptoms in cervical dystonia (CD) on the one hand and improvement of some special symptoms on the other hand after botulinum toxin (BoNT) therapy. Methods: 74 patients with idiopathic CD under continuous treatment in a BoNT outpatient department with at least three injections, completed a short questionnaire. They were asked whether pain, increased muscle tone and tension, reduced mobility of the head, abnormal head position, head tremor, or other symptoms had been present at the onset of BoNT-therapy and which symptoms were present at the time of recruitment. Patients had to rate actual severity of CD in percent of the severity of CD at the onset of BoNT-therapy. The TSUI score was determined by the treating physician. Blood samples were taken to analyze induction of neutralizing antibodies. Results: Mean improvement of CD reported by the patients and scored by the physician was about 50%. The frequency of all symptoms increased with duration of therapy. The symptom most frequently improved was abnormal head position. The longer the time span between onset of symptoms and onset of BoNT-therapy was, the higher was the actual TSUI score and the lower the improvement reported. Twelve patients had positive antibody tests. Conclusions: Patients experience a progression of CD, but recognize improvement of abnormal head position due to BoNT-therapy. The longer patients have been without BoNT- therapy, the poorer is the long-term outcome independent on duration of BoNT treatment. Therefore BoNT-therapy should be initiated as early as possible.

Clinical Implications of Difference in Antigenicity of Different Botulinum Neurotoxin Type A Preparations: Clinical Take-Home Messages from Our Research Pool and Literature

The three different botulinum toxin type A (BoNT/A) preparations being licensed in Europe and the U.S. differ in protein content, which seems to be a major factor influencing the antigenicity of BoNT/A. In the present study, several arguments out of our research pool were collected to demonstrate that the clinical response and antigenicity were different for the three BoNT/A preparations: some results of (1) a cross-sectional study on clinical outcome and antibody formation of 212 patients with cervical dystonia (CD) being treated between 2 and 22 years; 2) another cross-sectional study on the clinical aspects and neutralizing antibody (NAB) induction of 63 patients having developed partial secondary treatment under abobotulinum (aboBoNT/A) onabotulinumtoxin (onaBoNT/A) who were switched to incobotulinumtoxin (incoBoNT/A) in comparison to 32 patients being exclusively treated with incoBoNT/A. These results imply that (1) the presence of NAB cannot be concluded from the course of treatment, that (2) an increase in the dose and variability of outcome with treatment duration indicates the ongoing induction of NABs over time, that (3) the higher protein load of BoNT/A goes along with a higher incidence and prevalence of NAB induction and that (4) the best response to a BoNT/A is also dependent on the protein load of the preparation.

Use of AbobotulinumtoxinA in Adults with Cervical Dystonia: A Systematic Literature Review

Cervical dystonia (CD) is a neurological movement disorder characterized by sustained involuntary muscle contractions. First-line therapy for CD is intramuscular injections of botulinum neurotoxin (e.g., abobotulinumtoxinA) into the affected muscles. The objective of this systematic literature review is to assess the clinical evidence regarding the effects of abobotulinumtoxinA for treatment of CD in studies of safety, efficacy, patient-reported outcomes, and economic outcomes. Using comprehensive electronic medical literature databases, a search strategy was developed using a combination of Medical Subject Heading terms and keywords. Results were reviewed by two independent reviewers who rated the level of evidence. The search yielded 263 publications, of which 232 were excluded for being duplicate publications, not meeting the selection criteria, or failing to meet predefined eligibility criteria, leaving a total of 31 articles. Clinical efficacy, patient-reported outcomes, and safety data were in 6 placebo-controlled trials (8 articles), 6 active-controlled trials, and 16 observational studies (17 articles). Data on health economic outcomes were provided in one of the clinical trials, in two of the observational studies, and in one specific cost-analysis publication. This review demonstrated that the routine use of abobotulinumtoxinA in CD is well-established, effective, and generally well-tolerated, with a relatively low cost of treatment.

Cervical dystonia: factors deteriorating patient satisfaction of long-term treatment with botulinum toxin

OBJECTIVES

Botulinum toxin (BoNT) is an effective first-line treatment for cervical dystonia (CD). Despite generally good therapeutic efficacy, approximately 20-40% of CD patients do not achieve acceptable relief of the dystonic symptoms. The aim of this study was to identify factors of low patient satisfaction of long-term BoNT therapy for CD.

METHODS

In this case-control study CD patients treated with BoNT intramuscular injections for up to 24 years were assessed by two independent assessors in three validated scales: TWSTRS, Tsui and VAS for pain measurement. Data on received BoNT doses and treatment duration were obtained from medical history. All of participants rated their long-term treatment satisfaction compared to the therapy onset on a 0-3 scale.

RESULTS

Study was completed by 58 participants who were treated with BoNT for 9.0 ± 6.3 years and received a median of 19 injection cycles. None/low therapy satisfaction was reported by 20.7% of participants. Compared to moderate/good treatment satisfaction, CD patients with none/low BoNT efficacy had increased incidence of cervical pain (p =.018), enhanced mean VAS score for pain (p =.037) and had higher coexistence of oromandibular dystonia (p =.018). In addition, worse treatment satisfaction correlated with shorter time intervals between treatment cycles, enhanced scores of Tsui total, TWSTRS total, as well as TWSTRS subscales: severity, disability and pain.

CONCLUSION

Cervical pain and coexistence of oromandibular dystonia deteriorated long-term treatment satisfaction in CD patients. Higher scores of Tsui and TWSTRS subscales were correlated with worse subjective BoNT treatment response.

Benefits, Safety, and Adjunct Modality Prevalences of Long-Term Botulinum Toxin Injections for Cervical Dystonia and Myofascial Neck Pain: A Retrospective Cohort Study

Introduction

There is a paucity of long-term treatment benefit and safety data of botulinum toxin A (BTX-A) for cervical dystonia (CD) and myofascial neck pain syndrome (MPS). Additionally, the prevalence of adjunct modality uses during this period is unknown despite evolving practices.

Objective

To assess and compare treatment benefit, safety, and adjunct modality prevalences of long-term BTX-A injections between CD and MPS patients.

Design

Retrospective cohort study.

Setting

Private practice tertiary care clinics in Toronto.

Patients

Convenience sample of 37 (52.9%) CD and 33 (47.1%) MPS patients treated for a mean±SD duration of 7.2±4.3 and 8.3±4.7 years, respectively.

Interventions

BTX-A injections administered at least once yearly, for a duration longer than 1 year.

Main Outcome Measures

Toronto Western Spasmodic Torticollis Rating Scales (TWSTRS) for disability and pain, Patient Global Impression of Change (PGIC) score, time to peak effect, duration of total response, adverse effects, and prevalence of adjunct modalities.

Results

CD patients experienced improvements in TWSTRS disability (17.57±6.79 to 9.81±4.35, p<0.001) and pain (14.61±3.08 to 9.05±3.49, p<0.001) scores as well as PGIC score (52.00%±23.60% to 64.80%±23.60%, p=0.007). MPS patients experienced improvements in TWSTRS disability (15.86±7.70 to 10.07±7.01, p=0.01) and pain (15.25±4.09 to 10.85±4.49, p=0.01) scores. In both cohorts, there were no changes in time to peak effect and duration of total response. Adverse effects were minimal and self-limiting. Prevalences of adjunct modalities used by CD versus MPS patients were 28.13% versus 50.00% for anesthetic procedures, 23.08% versus 15.38% for image-guidance, 65.71% versus 56.25% for pectoralis minor injections, and 47.06% versus 53.13% for cannabis-use.

Conclusion

There were demonstrated and comparable treatment benefit, safety, and adjunct modality prevalences. Our study is the first to demonstrate that long-term BTX-A injections for MPS, although commonly used off-label, can be effective and safe.

Clinical relevance of neutralizing antibodies in botulinum toxin long-term treated still-responding patients with cervical dystonia

Background:

The aim of the study was to test the clinical relevance of neutralizing antibodies (NABs) in patients with cervical dystonia (CD) still responding to repeat injections with botulinum toxin type A (BoNT/A).

Methods:

Enzyme-linked immunosorbent assay (ELISA)-test evidence from a cross-sectional study on 221 CD-patients with treatment durations of between 2 and 21 years and still responding to repeat BoNT/A-injections showed the presence of antibodies against BoNT/A in 39 patients. A mouse hemi-diaphragm (MHDA) confirmation test was performed in these 39 ELISA-positive patients, and demographic (age, sex, age at onset of CD) and treatment-related (duration of treatment, mean dose of the last 10 injections, TSUI-score, patient’s subjective scoring of the treatment effect, patient’s scoring of quality of life by means of the CDQ24-questionnaire) data from these 39 patients were compared with data from ELISA-negative patients. Paralysis time, the MHDA outcome measure, was correlated with clinical data.

Results:

The ELISA-positive CD-patients had significantly higher TSUI-scores (p < 0.015), and had been treated for significant longer (p < 0.022) and with significantly higher doses (p < 0.001). Patient’s rating of BoNT/A-treatment effect and quality of life tended to be worse in ELISA-positive compared with ELISA-negative patients. The paralysis time of ELISA-positive patients was significantly correlated with the mean dose of the last 10 injections (p < 0.027) and the pain subscore of the CDQ24 (p < 0.012).

Conclusions:

Presence of NABs is clinically relevant in CD, leading to a significantly worse head position, therapy with significantly higher BoNT/A doses, and a correlation between the CDQ24 pain-subscore and antibody titers.

How satisfied are cervical dystonia patients after 3 years of botulinum toxin type A treatment? Results from a prospective, long-term observational study

Background

Patients with cervical dystonia (CD) typically require regular injections of botulinum toxin to maintain symptomatic control. We aimed to document long-term patient satisfaction with CD symptom control in a large cohort of patients treated in routine practice.

Methods

This was a prospective, international, observational study (NCT01753349) following the course of adult CD treated with botulinum neurotoxin type A (BoNT-A) over 3 years. A comprehensive clinical assessment status was performed at each injection visit and subjects reported satisfaction in two ways: satisfaction with symptom control at peak effect and at the end of treatment cycle.

Results

Subject satisfaction remained relatively stable from the first to the last injection visit. At 3 years, 89.9% of subjects reported satisfaction with symptom control at peak effect and 55.6% reported satisfaction with symptom control at end of treatment cycle. By contrast, objective ratings of CD severity showed an overall reduction over 3 years. Mean ± SD Toronto Western Spasmodic Rating Scale (TWSTRS) Total scores (clinician assessed at end of treatment cycle) decreased from 31.59 ± 13.04 at baseline to 24.49 ± 12.43 at 3 years (mean ± SD reduction from baseline of − 6.97 ± 11.56 points). Tsui scale scores also showed gradual improvement; the percent of subjects with a tremor component score of 4 reduced from 12.4% at baseline to 8.1% at 3 years.

Conclusions

Despite objective clinical improvements over 3 years, subject satisfaction with symptom control remained relatively constant, indicating that factors other than symptom control also play a role in patient satisfaction.

Electronic supplementary material

The online version of this article (10.1007/s00415-019-09527-2) contains supplementary material, which is available to authorized users.

Botulinum Toxin Induced Atrophy: An Uncharted Territory

Botulinum neurotoxins (BoNTs) produce local chemo-denervation by cleaving soluble N-ethylmaleimide-sensitive factor activating protein receptor (SNARE) proteins. Botulinum neurotoxins are therapeutically indicated in several neurological disorders and have been in use for three decades. The long-term efficacy, safety, and side effects of BoNTs have been well documented in the literature. However, the development of muscle atrophy following chronic exposure to BoNTs has not received sufficient attention. Muscle atrophy is not only cosmetically distressing, but also has an impact on future injections. An extensive literature search was conducted on atrophy and mechanisms of atrophy. Five hundred and four relevant articles in the English language were reviewed. This review revealed the surprising lack of documentation of atrophy within the literature. In addition, as demonstrated in this review, the mechanisms and the clinical factors that may lead to atrophy have also been poorly studied. However, even with this limited information it is possible to indicate factors that could modify the clinical approach to botulinum toxin injections. This review highlights the need for further study of atrophy following BoNT injections.

Longitudinal studies of botulinum toxin in cervical dystonia: Why do patients discontinue therapy?

BACKGROUND

Numerous studies have established botulinum toxin (BoNT) to be safe and effective for the treatment of cervical dystonia (CD). Despite its well-documented efficacy, there has been growing awareness that a significant proportion of CD patients discontinue therapy. The reasons for discontinuation are only partly understood.

METHODS

This summary describes longitudinal studies that provided information regarding the proportions of patients discontinuing BoNT therapy, and the reasons for discontinuing therapy. The data come predominantly from un-blinded long-term follow-up studies, registry studies, and patient-based surveys.

RESULTS

All types of longitudinal studies provide strong evidence that BoNT is both safe and effective in the treatment of CD for many years. Overall, approximately one third of CD patients discontinue BoNT. The most common reason for discontinuing therapy is lack of benefit, often described as primary or secondary non-response. The apparent lack of response is only rarely related to true immune-mediated resistance to BoNT. Other reasons for discontinuing include side effects, inconvenience, cost, or other reasons.

DISCUSSION

Although BoNT is safe and effective in the treatment of the majority of patients with CD, approximately one third discontinue. The increasing awareness of a significant proportion of patients who discontinue should encourage further efforts to optimize administration of BoNT, to improve BoNT preparations to extend duration or reduce side effects, to develop add-on therapies that may mitigate swings in symptom severity, or develop entirely novel treatment approaches.

[Conversion ratio between different botulinum neuroprotein product in neurological practice]

Despite nearly 30 years of experience in the application of botulinum toxin type A (BTA) in clinical practice, many fundamental questions of therapy remain valid. There are 5 botulinum toxin type A used for neurological indications in the Russian Federation in 2017. They contain different number of active neuroprotein (150 kDa) in a therapeutic dose of the drug that may have a potential impact on the efficacy and duration of action. The current SmPC of each BTA stated that the unit of activity is unique and can not be compared with any other BTA. In scientific publications one can find many details concerning the equivalence doses of onabotulinumtoxin A (botox) and abobotulinumtoxin A (dysport) and the ratio of units varies from 1:1 to 1:11. However, according to clinical guidelines, systematic reviews and high quality research evidence of recent years, the ratio of units of abobotulinumtoxin A (dysport) and onabotulinumtoxin A (botox) is 3(2,5):1. Use of a fixed ratio of units is possible only when switching from one drug to another or in case of limiting access to specific drug. Botulinum toxin type A is the first line of therapy in the treatment of several neurological diseases. The most commonly used drugs of botulinum toxin type A (botox, dysport, xeomin) have a significant evidence base that confirms their efficacy and optimal safety profile. The main difference between botulinum toxin type A is their potential activity of action, i.e., activity units and total therapeutic dose.

Clinical Practice: Evidence-Based Recommendations for the Treatment of Cervical Dystonia with Botulinum Toxin

Cervical dystonia (CD) is the most frequent form of focal dystonia. Symptoms often result in pain and functional disability. Local injections of botulinum neurotoxin are currently the treatment of choice for CD. Although this treatment has proven effective and is widely applied worldwide, many issues still remain open in the clinical practice. We performed a systematic review of the literature on botulinum toxin treatment for CD based on a question-oriented approach, with the aim to provide practical recommendations for the treating clinicians. Key questions from the clinical practice were explored. Results suggest that while the beneficial effect of botulinum toxin treatment on different aspects of CD is well established, robust evidence is still missing concerning some practical aspects, such as dose equivalence between different formulations, optimal treatment intervals, treatment approaches, and the use of supportive techniques including electromyography or ultrasounds. Established strategies to prevent or manage common side effects (including excessive muscle weakness, pain at injection site, dysphagia) and potential contraindications to this treatment (pregnancy and lactation, use of anticoagulants, neurological comorbidities) should also be further explored.

Neutralizing Antibody and Botulinum Toxin Therapy: A Systematic Review and Meta-analysis

The formation of neutralizing antibodies (NAbs) directed specifically against the active neurotoxin part of the botulinum neurotoxin (BoNT) complex is often cited as a major cause of secondary non-responsiveness (SnR) to treatment. This systematic and meta-analytic review evaluates the frequency of NAbs among patients treated with BoNT therapy for any clinical indication. A comprehensive database search strategy was designed to retrieve relevant clinical data from the published literature up to April 2013. All English-language publications that analyzed NAbs prevalence in more than ten patients were included, regardless of BoNT formulation, assay method, and study design. For the meta-analysis, patients were divided into three categories: secondary nonresponse (SnR) patients, clinically responding patients and all patients, independently of BoNT responsiveness. The meta-analysis included 61 studies reporting data for 8525 patients; 4972 dystonic patients, 1170 patients with spasticity, 294 patients with urologic indications, 396 patient with hyperhidrosis, 1659 patients with glabellar line, and 34 patients with hypersalivation. Among the ‘‘all patients’’ group NAbs frequency was 20%for dystonia, 5.9%for spasticity, and 2.7% for urologic patients and 1.1% for other conditions. The prevalence of NAbs was lower (3.5%) among clinically responding patients and higher in 53.5%SnR patients. About a half of patients with SnR do not have NAbs. NAbs was high among patients treated with RIMA but it was not associated with clinical non-responsiveness. Meta-analysis of the frequency of NAbs and SnR are limited by the heterogeneity of study design and reported outcomes. Indeed the analysis of several factors that can influence the development of NAbs, i.e.,MHCof patients, frequency and site of injection, injection technique, cumulative dose, and toxin denaturation, was not specifically evaluated due to the paucity and heterogeneity of data. The identification of all these missing data should be taken into account in order to improve the methodology of future studies.

Efficacy and safety of abobotulinumtoxinA liquid formulation in cervical dystonia: A randomized-controlled trial

BACKGROUND

Approved botulinum toxin A products require reconstitution. AbobotulinumtoxinA solution for injection is a ready-to-use liquid formulation of abobotulinumtoxinA.

OBJECTIVES

The objective of this study was to demonstrate the superior efficacy of abobotulinumtoxinA solution for injection to placebo and to test the noninferior efficacy of abobotulinumtoxinA solution for injection versus abobotulinumtoxinA (dry formulation) in cervical dystonia.

METHODS

This was a phase-3, multicenter, prospective, double-blind, randomized, active, and placebo-controlled study (N = 369). Patients with cervical dystonia were randomized (3:3:1) to abobotulinumtoxinA solution for injection 500 U, abobotulinumtoxinA 500 U, or placebo. Following the double-blind phase, patients received abobotulinumtoxinA solution for injection, open-label, for up to 4 cycles. The primary outcome was change from baseline at week 4 of the Toronto Western Spasmodic Torticollis Rating Scale total score. Secondary measures included change from baseline or cycle baseline in Toronto Western Spasmodic Torticollis Rating Scale scores.

RESULTS

At week 4, both products were superior to placebo (Toronto Western Spasmodic Torticollis Rating Scale total score least square mean decrease from baseline, abobotulinumtoxinA solution for injection 500 U -12.5, abobotulinumtoxinA 500 U -14.0, placebo -3.9; P < .0001 vs placebo). The noninferiority limit of 3 points in the Toronto Western Spasmodic Torticollis Rating Scale total score at week 4 was not met for abobotulinumtoxinA solution for injection versus abobotulinumtoxinA. Toronto Western Spasmodic Torticollis Rating Scale total score reductions were maintained for up to 4 cycles of abobotulinumtoxinA solution for injection open-label follow-up treatment. Safety profiles of abobotulinumtoxinA solution for injection and abobotulinumtoxinA were similar, with dysphagia and injection-site pain the most frequent drug-related adverse events.

CONCLUSIONS

Although the predefined noninferiority criterion was not met, abobotulinumtoxinA solution for injection was similarly effective to freeze-dried abobotulinumtoxinA in reducing Toronto Western Spasmodic Torticollis Rating Scale total scores with a similar safety profile. AbobotulinumtoxinA solution for injection efficacy was maintained with chronic open-label treatment, and this novel formulation may add convenience as well as dosing accuracy to treatment with abobotulinumtoxinA. © 2016 International Parkinson and Movement Disorder Society.

High Botulinum Toxin-Neutralizing Antibody Prevalence Under Long-Term Cervical Dystonia Treatment

BACKGROUND

The aim of this study was to determine the prevalence of neutralizing antibodies in a large cohort of long-term treated patients with cervical dystonia (CD) still responding to repetitive injections with botulinum toxin (BoNT).

METHODS

Consecutively recruited CD patients (n = 221) under long-term BoNT treatment (≥2-21 years) underwent a clinical examination at the same time blood samples were taken for neutralizing antibody determination. Collected data included demographics, mean dose of the last 10 botulinum injections, treatment duration, Tsui score for CD severity, and patients' subjective impression of treatment effect. Blood samples were screened for antibody presence by ELISA; positive samples were further analyzed by mouse hemidiaphragm test. The two laboratories performing antibody testing were blinded to the coded samples.

RESULTS

Antibody status could be determined for 212 patients; 39 (18.4%) were ELISA positive and 31 (14.6%) additionally positive in the mouse hemidiaphragm test. Patients with positive neutralizing antibody titers had significantly higher Tsui scores and were treated for a significantly longer time with significantly higher doses. There were no differences between male and female patients and between onabotulinumtoxinA- and abobotulinumtoxinA-treated patients. When BoNT preparations had been switched during the last 10 injections, a significantly higher proportion of neutralizing antibody-positive patients was detected.

CONCLUSIONS

Neutralizing antibody prevalence in long-term treated, still responding CD patients is substantially higher than suggested by follow-up studies with a shorter time frame. It should therefore be emphasized that antigenicity of BoTN preparations is still a relevant problem and should be taken into account in long-term treatment decisions.

British Neurotoxin Network recommendations for managing cervical dystonia in patients with a poor response to botulinum toxin

Botulinum toxin (BoNT) injections are an effective treatment for cervical dystonia. Approximately 20% of patients eventually stop BoNT treatment, mostly because of treatment failure. These recommendations review the different therapeutic interventions for optimising the treatment in secondary poor responder patients. Immunoresistance has become less common over the years, but the diagnosis has to be addressed with a frontalis test or an Extensor Digitorum Brevis test. In case of immunoresistance to BoNT-A, we discuss the place the different therapeutic options (BoNT-A holidays, BoNT-B injections, alternative BoNT-A injections, deep brain stimulation). When poor responders are not immunoresistant, they benefit from reviewing (1) injections technique with electromyography or ultrasound guidance, (2) muscles selection and (3) dose of BoNT. In addition, in both scenarios, a holistic approach including drug treatment, retraining and psychological support is valuable in the management of these complex and severe cervical dystonia.

Conversion Ratio between Botox®, Dysport®, and Xeomin® in Clinical Practice

Botulinum neurotoxin has revolutionized the treatment of spasticity and is now administered worldwide. There are currently three leading botulinum neurotoxin type A products available in the Western Hemisphere: onabotulinum toxin-A (ONA) Botox(®), abobotulinum toxin-A (ABO), Dysport(®), and incobotulinum toxin A (INCO, Xeomin(®)). Although the efficacies are similar, there is an intense debate regarding the comparability of various preparations. Here we will address the clinical issues of potency and conversion ratios, as well as safety issues such as toxin spread and immunogenicity, to provide guidance for BoNT-A use in clinical practice. INCO was shown to be as effective as ONA with a comparable adverse event profile when a clinical conversion ratio of 1:1 was used. The available clinical and preclinical data suggest that a conversion ratio ABO:ONA of 3:1-or even lower-could be appropriate for treating spasticity, cervical dystonia, and blepharospasm or hemifacial spasm. A higher conversion ratio may lead to an overdosing of ABO. While uncommon, distant spread may occur; however, several factors other than the pharmaceutical preparation are thought to affect spread. Finally, whereas the three products have similar efficacy when properly dosed, ABO has a better cost-efficacy profile.

Pharmaceutical, biological, and clinical properties of botulinum neurotoxin type A products

Botulinum neurotoxin injections are a valuable treatment modality for many therapeutic indications and have revolutionized the field of aesthetic medicine so that they are the leading cosmetic procedure performed worldwide. Studies show that onabotulinumtoxinA, abobotulinumtoxinA, and incobotulinumtoxinA are comparable in terms of clinical efficacy. Differences between the products relate to the botulinum neurotoxin complexes, specific biological potency, and their immunogenicity. Protein complex size and molecular weight have no effect on biological activity, stability, distribution, or side effect profile. Complexing proteins and inactive toxin (toxoid) content increase the risk of neutralizing antibody formation, which can cause secondary treatment failure, particularly in chronic disorders that require frequent injections and long-term treatment. These attributes could lead to differences in therapeutic outcomes, and, given the widespread aesthetic use of these three neurotoxin products, physicians should be aware of how they differ to ensure their safe and effective use.

Clinical Characteristics and Response to Long-Term Botulinum Toxin Type A Therapy in Patients with Cervical Dystonia at a Neurology Clinic

INTRODUCTION

To determine the demographic and clinical characteristics and response to botulinum toxin type A (BoNT-A) therapy in patients with cervical dystonia (CD).

METHOD

A retrospective analysis of the detailed medical records of the patients with CD, followed up at our Botulinum Toxin Outpatient Clinic from 1998 to 2012, was performed. The treatment data were compared between the patients with primary CD and those with secondary CD; between patients receiving BoNT-A treatment for more than 5 years and less than five years, and between first applications and last applications.

RESULTS

Fifty-seven patients (56.15% women) with CD were included in this study. The mean age was 41.01±13.42 years, the mean age at symptom onset was 32.93±15.45 years, and the mean dystonia duration was 8.10±8.5 years. The interval between onset of symptom and first BoNT-A treatment was 5.94±9.06 years, the duration of BoNT-A treatment was 36.13±29.17 months, and the number of applications was 8.48±6.23 in 45 patients with CD who were under treatment with BoNT-A for more than 1 year and had received at least three injections before. There was no difference between the patients with primary and secondary CD in terms of treatment results. The injection interval of the patients receiving BoNT-A treatment for more than 5 years and less than 5 years was 18.37±5.10 and 14.43±2.36 weeks, respectively (p=.001). There were no differences in the other treatment values. The mean doses were 559.00±147.60 vs. 681.66±188.09 units (p=.0001), the durations of improvement were 11.82±2.71 vs. 13.00±4.00 weeks (p=.014), the response scores were 2.71±.3 vs. 3.02±.5 (p=.002), the response ratings were 64.66%±16.18 vs. 71.22%±17.29 (p=.001), and the numbers of muscles applied were 3.15±1.16 vs. 3.51±0.99 (p=.012) in the first and last applications, respectively.

CONCLUSION

There were no differences between the response of the patients with primary and secondary CD. Our results showed a statistically significant increase in the mean dose of BoNT-A, the response rating, the number of muscles applied, the duration of improvement, and the injection interval over time.

Long-term efficacy, safety, and side effect profile of botulinum toxin in dystonia: a 20-year follow-up

Most long-term studies of the efficacy and safety profile of botulinum toxin (BoNT) in the treatment of dystonia are limited by lack of objective assessments, relatively small sample size, or short follow-up periods. We present one of the longest follow-up studies of BoNT treatment. This is a retrospective, longitudinal study that analyzes data on 89 patients treated with BoNT for dystonia at our Movement Disorders Clinic for up to 26 years (mean follow-up period of 18.5 years). The mean ages at the time of the first and last injections were 49 and 68 years old, respectively. The most common diagnoses were cervical dystonia (N = 51), blepharospasm (N = 34), and oromandibular dystonia (N = 26). The total number of onabotulinumtoxinA units received during the first injection was 140.3 as compared to 224.5 at the last injection (p < 0.0001). The global response effect was 3.18 after the first injection session and 3.57 after the last injection (p < 0.0001). The duration of response after the initial injection session and at the last injection was 16.33 weeks versus 19.42 weeks (p 0.0037), respectively. Adverse events, typically related to injection site, were reported in 19% of the visits. This series of dystonia patients with the longest reported treatment with BoNT provide evidence that in selected patients repeated chemodenervation is associated with sustained symptomatic benefit, decreased latency effect, and prolonged duration of therapeutic response. Despite the higher requirement of mean units per visit over time, only 19% of all treatment cycles are associated with adverse, but tolerable, side effects.

Blepharospasm: long-term treatment with either Botox®, Xeomin® or Dysport®

Botulinum toxin (BT) therapy is the treatment of choice for blepharospasm (BPS). Currently available BT type A drugs include Botox(®), Dysport(®) and Xeomin(®). Until now, there are few long-term studies on BT therapy for BPS. This is the first long-term study comparing all three major BT drugs. We collected treatment, efficacy and adverse effect data on BPS patients treated with either Botox(®), Dysport(®) or Xeomin(®) for at least eight consecutive treatments. Two hundred and eighty-eight patients (208 females, 80 males, age 62 ± 12 years) were included in this study. The treatment time was 11.2 ± 4.1 years covering 10,701 injection series. Doses were 47 ± 10 MU for Botox(®), 120 ± 35 MU for Dysport(®) and 62 ± 11 MU for Xeomin(®) (Botox(®) dose vs Xeomin(®) dose: p < 0.001, unpaired t test). 85 % of all patients had stable doses. The onset of the therapeutic effect was after 6.1 ± 3.3 days and its duration lasted 10.2 ± 3.5 weeks. The Global Clinical Improvement (GCI, 0 = no, 1 = slight, 2 = moderate, 3 = marked improvement in severity and function) as estimated by the patient was 2.5 ± 0.6. It was stable in 90% of the patients. Adverse effect frequency was 3.0% (ptosis 2.3%, dry eye 0.5%, diplopia 0.2%). None of these findings was significantly different between Botox(®), Dysport(®) and Xeomin(®). Our study, one of the largest studies on BT therapy of BPS and the study with the longest follow-up, confirms that BT therapy produces robust clinical improvement which is stable throughout the treatment time. Therapeutic effects start after 6.1 days and last for about 10 weeks before they start to vanish. With this, they are approximately 2 weeks shorter than the recommended inter-injection interval. Adverse effects were rare, mild and always transient. BT therapy is a safe and effective treatment for BSP. Shorter inter-injection intervals may improve therapeutic results.

Systematic review and meta-analysis of the duration of clinical effect of onabotulinumtoxinA in cervical dystonia

Background

Botulinum toxins are considered first-line therapy for treatment of cervical dystonia (CD) and must be injected on a repeat basis. Understanding the duration of clinical benefit of botulinum toxins and its impact on health care utilization are thus important in the contemporary environment. However, there is currently no overall consensus on the duration of effect of onabotulinumtoxinA in the treatment of CD. We performed a systematic review and meta-analysis to identify the duration of effect of onabotulinumtoxinA in CD and investigate factors that may influence it.

Methods

A systematic literature search identified prospective or retrospective studies reporting duration of effect of onabotulinumtoxinA for the treatment of CD. Inclusion criteria included peer-reviewed, non-review, English-language articles published between January 1980 and January 2013. A formal meta-analysis using Comprehensive Meta-Analysis Version 2 was conducted to identify the duration of effect of onabotulinumtoxinA in the treatment of CD; both fixed and random effects models were performed. Subgroup analyses were performed to identify factors that influenced the duration of effect of onabotulinumtoxinA.

Results

A total of 18 studies (including >1,900 patients) met the inclusion criteria and were used for the meta-analysis. The mean duration of effect of onabotulinumtoxinA in CD was found to be 93.2 days (95% CI 91.8-94.6 days) for the fixed effects model and 95.2 days (95% CI 88.9-101.4 days) for the random effects model. A meta-regression found that dose of onabotulinumtoxinA and country of origin influenced the duration of effect of onabotulinumtoxinA, whereas quality score of the article and study type did not. In particular, doses ≥180 Units were associated with longer durations of effect than doses <180 Units (107-109 days vs. 86-88 days, respectively; p < 0.01). Limitations included pooling studies that used discrete definitions of duration and had different designs and study quality.

Conclusions

Based on the published literature, the mean duration of effect of onabotulinumtoxinA in CD was 93-95 days (13.2-13.5 weeks). This suggests that, in general, patients with CD treated with onabotulinumtoxinA should require ~4 treatments per year.

Neutralizing antibodies to botulinum neurotoxin type A in aesthetic medicine: five case reports

Botulinum neurotoxin injections are a valuable treatment modality for many therapeutic indications as well as in the aesthetic field for facial rejuvenation. As successful treatment requires repeated injections over a long period of time, secondary resistance to botulinum toxin preparations after repeated injections is an ongoing concern. We report five case studies in which neutralizing antibodies to botulinum toxin type A developed after injection for aesthetic use and resulted in secondary treatment failure. These results add to the growing number of reports in the literature for secondary treatment failure associated with high titers of neutralizing antibodies in the aesthetic field. Clinicians should be aware of this risk and implement injection protocols that minimize resistance development.

Very early reduction in efficacy of botulinum toxin therapy for cervical dystonia in patients with subsequent secondary treatment failure: a retrospective analysis

The objective of this study was to estimate the probability of development of partial secondary treatment failure (PSTF) in patients with cervical dystonia (CD) who had been treated over up to 9 years with repetitive intramuscular injections of botulinum neurotoxin type A (BoNT/A). The temporal course of treatment response in patients in whom PSTF was detected retrospectively was compared to patients with a normal clinical response. For this purpose, charts of all CD patients treated in our outpatient clinic between 1988 and 2001 were retrospectively analyzed. Extracted data included time of all injections, dose per visit, disease severity measured by TSUI scores, and time of determination of neutralizing antibodies. Final data analysis using a special formal definition of PSTF was based on charts of 568 patients having exclusively been treated with abobotulinumtoxinA. PSTF onset was observed in our CD cohort during the entire treatment period analyzed, with no clustering at any time point. Probability to develop PSTF was 14.5 % in 9 years. Thus, mean PSTF incidence was 1.6 % per year. The mean TSUI score of patients with retrospectively defined PSTF (n = 33) became already significantly worse after the second injection when compared with the group without PSTF (n = 535). Our data indicate that clinical response in patients developing PSTF later on differs from that of patients without PSTF already very early in the course of botulinum neurotoxin type A treatment, and that PSTF remains undetected at this early stage. Reduced response may therefore be present in a number of CD patients who think they still respond normally to continuous BoNT/A treatment.

Long-term efficacy and safety of incobotulinumtoxinA injections in patients with cervical dystonia

INTRODUCTION

Previously, controlled trials have demonstrated the efficacy and tolerability of fixed doses of incobotulinumtoxinA (Xeomin, NT 201, botulinum toxin type A free from complexing proteins) to treat cervical dystonia (CD). To explore the clinical relevance of these findings, this study evaluated long-term use of flexible dosing regimens of incobotulinumtoxinA in a setting close to real-life clinical practice.

METHODS

Patients with CD received five injection sessions of incobotulinumtoxinA using flexible intervals (10-24 weeks) and dosing (≤300 Units) based on patients' needs. Outcome measures included Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), the Dystonia Discomfort Scale (DDS), Investigator Global Assessment of Efficacy (IGAE) and Patient Evaluation of Global Response (PEGR).

RESULTS

Of 76 patients enrolled (men: 34%; naïve to botulinum toxin: 25%), 64 completed the study, receiving treatment over a duration of 49.3-114.1 weeks (total maximum duration: 121 weeks). Mean TWSTRS-Total and DDS scores significantly improved from study baseline to 4 weeks after each injection session (ranges of improvement: TWSTRS-Total: -11.7 to -14.3; DDS: -20.2 to -23.0). Up to 81.6% of investigators rated the efficacy as 'good' or 'very good' (IGAE) and up to 78.9% of patients rated the treatment response as 'improved' (PEGR). The most common adverse events were dysphagia, nasopharyngitis and headache.

CONCLUSIONS

In this long-term study, incobotulinumtoxinA was administered using more flexible dosing regimens than those permitted in previous controlled trials. Repeated injections of highly purified incobotulinumtoxinA are effective and well tolerated for the treatment of CD in a setting close to real-life clinical practice.

Diffusion, spread, and migration of botulinum toxin

Botulinum toxin (BoNT) is an acetylcholine release inhibitor and a neuromuscular blocking agent used for the treatment of a variety of neurologic and medical conditions. The efficacy and safety of BoNT depends on accurate selection and identification of intended targets but also may be determined by other factors, including physical spread of the molecule from the injection site, passive diffusion, and migration to distal sites via axonal or hematogenous transport. The passive kinetic dispersion of the toxin away from the injection site in a gradient-dependent manner may also play a role in toxin spread. In addition to unique properties of the various BoNT products, volume and dilution may also influence local and systemic distribution of BoNT. Most of the local and remote complications of BoNT injections are thought to be due to unwanted spread or diffusion of the toxin's biologic activity into adjacent and distal muscles. Despite widespread therapeutic and cosmetic use of BoNT over more than three decades, there is a remarkable paucity of published data on the mechanisms of distribution and its effects on clinical outcomes. The primary aim of this article is to critically review the available experimental and clinical literature and place it in the practical context.

Long-term efficacy and safety of botulinum toxin injections in dystonia

Local chemodenervation with botulinum toxin (BoNT) injections to relax abnormally contracting muscles has been shown to be an effective and well-tolerated treatment in a variety of movement disorders and other neurological and non-neurological disorders. Despite almost 30 years of therapeutic use, there are only few studies of patients treated with BoNT injections over long period of time. These published data clearly support the conclusion that BoNT not only provides safe and effective symptomatic relief of dystonia but also long-term benefit and possibly even favorably modifying the natural history of this disease. The adverse events associated with chronic, periodic exposure to BoNT injections are generally minor and self-limiting. With the chronic use of BoNT and an expanding list of therapeutic indications, there is a need to carefully examine the existing data on the long-term efficacy and safety of BoNT. In this review we will highlight some of the aspects of long-term effects of BoNT, including efficacy, safety, and immunogenicity.

Elimination of dysphagia using ultrasound guidance for botulinum toxin injections in cervical dystonia

INTRODUCTION

Dysphagia is a common side effect after botulinum toxin injections for cervical dystonia, with an incidence of 10-40%, depending upon the study and dose used.

METHODS

Our study consisted of 5 preselected women who met criteria for cervical dystonia and subsequent dysphagia after electromyography (EMG)-guided injections. Injections were performed with ultrasound (US) imaging, and the effects on swallowing were examined. Separately, sternocleidomastoid (SCM) thickness in healthy controls and treated patients was measured.

RESULTS

There were 34 episodes of dysphagia over 98 injection sessions using EMG guidance for a cumulative rate of 34.7%. Using US plus EMG guidance, there was 0% dysphagia across 27 injection sessions. SCM thickness was <1.1 cm.

CONCLUSION

US combined with EMG guidance eliminated recurrent dysphagia after botulinum toxin treatment, possibly by keeping the injectate within the SCM.

Use of injectable spasticity management agents in a cancer center

PURPOSE

This study aims to analyze the utilization and effectiveness of injectable spasticity medications by the physiatry team at a referral-based tertiary cancer center.

METHODS

A retrospective review and analysis of patient and injection characteristics were obtained from patients who had received onabotulinum toxin or phenol nerve block injections from December 1, 2007 through January 31, 2012. Out of 3,724 physiatry consultations during this period, 20 (less than 1 %) different cancer patients received a total of 54 total procedures.

RESULTS

The majority of patients (17/20, 85 %) had a positive response to the injection. A positive response to the injection was defined by: (1) if the patient qualified to receive and was given another injection or (2) if there is a record of improvement if they did not receive another injection. A total of ten of 20 (50 %) patients received only one injection. Of these, seven of ten (70 %) reported a positive response to the injected agent. Those with only one injection tended to live farther away and die sooner. Four of 54 (7 %) injection procedures resulted in undesirable reported side effects (two for phenol, two for botulinum toxin). Nine of 54 (17 %) procedures occurred while the patients were on a chemotherapy protocol. All patients were injected at least 1 year out from initial diagnosis.

Clinical relevance of botulinum toxin immunogenicity

Botulinum toxin type A is a 150 kD protein produced by Clostridium botulinum, which exists in a complex with up to six additional proteins. The ability of botulinum toxin to inhibit acetylcholine release at the neuromuscular junction has been exploited for use in medical conditions characterized by muscle hyperactivity. As such, botulinum toxin is widely recommended by international treatment guidelines for movement disorders and it has a plethora of other clinical and cosmetic indications. The chronic nature of these conditions requires repeated injections of botulinum toxin, usually every few months. Multiple injections can lead to secondary treatment failure in some patients that may be associated with the production of neutralizing antibodies directed specifically against the neurotoxin. However, the presence of such antibodies does not always render patients non-responsive. The reported prevalence of immunoresistance varies greatly, depending on factors such as study design and treated indication. This review presents what is currently known about the immunogenicity of botulinum toxin and how this impacts upon patient non-response to treatment. The complexing proteins may act as adjuvants and stimulate the immune response. Their role and that of neutralizing and non-neutralizing antibodies in the response to botulinum toxin is discussed, together with an assessment of current neutralizing antibody measurement techniques. Botulinum toxin preparations with different compositions and excipients have been developed. The major commercially available preparations of botulinum toxin are Botox® (onabotulinumtoxinA; Allergan, Inc., Ireland), Dysport® (abobotulinumtoxinA; Ipsen Ltd, UK), and Xeomin® (incobotulinumtoxinA; botulinum toxin type A [150 kD], free from complexing proteins; NT 201; Merz Pharmaceuticals GmbH, Germany). The new preparations of botulinum toxin aim to minimize the risk of immunoresistance in patients being treated for chronic clinical conditions.

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).

A botulinum toxin A treatment algorithm for de novo management of torticollis and laterocollis

OBJECTIVES

Few studies have investigated the injection patterns for botulinum toxin type A for the treatment of heterogeneous forms of cervical dystonia (CD). This large, prospective, open-label, multicentre study aimed to evaluate the effectiveness and safety of 500 U botulinum toxin A for the initial treatment according to a standardised algorithm of the two most frequent forms of CD, predominantly torticollis and laterocollis.

DESIGN

Patients (aged ≥ 18 years) with CD not previously treated with botulinum neurotoxin therapy were given one treatment with 500 U Dysport, according to a defined intramuscular injection algorithm based on clinical assessment of direction of head deviation, occurrence of shoulder elevation, occurrence of tremor (all evaluated using the Tsui rating scale) and hypertrophy of the sternocleidomastoid muscle.

RESULTS

In this study, 516 patients were enrolled, the majority of whom (95.0%) completed treatment. Most patients had torticollis (78.1%). At week 4, mean Tsui scores had significantly decreased by -4.01, -3.76 and -4.09 points in the total, torticollis and laterocollis populations, respectively. Symptom improvement was equally effective between groups. Tsui scores remained significantly below baseline at week 12 in both groups. Treatment was well tolerated; the most frequent adverse events were muscular weakness (13.8%), dysphagia (9.9%) and neck pain (6.6%).

CONCLUSIONS

Dysport 500 U is effective and well tolerated for the de novo management of a range of heterogeneous forms of CD, when using a standardised regimen that allows tailored dosing based on individual symptom assessment. Clinical trials information (NCT00447772; clinicaltrials.gov).

Hemifacial spasm and reinnervation synkinesias: long-term treatment with either Botox or Dysport

Botulinum toxin is considered the treatment of choice for hemifacial spasm (HFS) and reinnervation synkinesias (RS). We present 133 patients with HFS (n = 97) and RS (n = 36) who have been treated with either Botox (n = 78) or Dysport (n = 55) exclusively for 6 years (range 2-12 years). The Botox dose was 21 +/- 8 MU, the Dysport dose 46 +/- 22 MU. The therapeutic effect started after 7.1 +/- 2.3 days and lasted for 12.5 +/- 3.9 weeks. It was stable throughout the observation period in 85% of all patients. Adverse effects occurred in 5.4% of injection series. No patient terminated treatment because of unsatisfactory results. Secondary therapy failure did not occur. With an effective conversion ratio of Botox:Dysport = 1:2.56 there were no differences between both drugs with respect to therapeutic efficacy and adverse effects thus confirming the hypothesis that there may not be intrinsic differences between both products.