A double blind, randomised, parallel group study to investigate the dose equivalence of Dysport and Botox in the treatment of cervical dystonia

Practical guidance for CD management involving treatment of botulinum toxin: a consensus statement

Cervical dystonia is a neurological movement disorder causing abnormal posture of the head. It may be accompanied by involuntary movements which are sometimes tremulous. The condition has marked effects on patients’ self-image, and adversely affects quality of life, social relationships and employment. Botulinum neurotoxin (BoNT) is the treatment of choice for CD and its efficacy and safety have been extensively studied in clinical trials. However, current guidelines do not provide enough practical information for physicians who wish to use this valuable treatment in a real-life setting. In addition, patients and physicians may have different perceptions of what successful treatment outcomes should be. Consequently, an international group of expert neurologists, experienced in BoNT treatment, met to review the literature and pool their extensive clinical experience to give practical guidance about treatment of CD with BoNT. Eight topic headings were considered: the place of BoNT within CD treatment options; patient perspectives and desires for treatment; assessment and goal setting; starting treatment with BoNT-A; follow-up sessions; management of side effects; management of non-response; switching between different BoNT products. One rapporteur took responsibility for summarising the current literature for each topic, while the consensus statements were developed by the entire expert group. These statements are presented here along with a discussion of the background information.

Comparison of the efficacy of onabotulinumtoxinA and abobotulinumtoxinA at the 1: 3 conversion ratio for the treatment of asymmetry after long-term facial paralysis

BACKGROUND

Botulinum toxin A injection into the nonparalyzed side is used to treat asymmetry resulting from facial palsy. OnabotulinumtoxinA and abobotulinumtoxinA units are not equivalent. The authors compared the conversion ratio of 1:3 in patients with facial palsy.

METHODS

Fifty-five patients (age, 16 to 67 years; 43 women) with longstanding facial palsy were randomly treated with either onabotulinumtoxinA (n = 25) or abobotulinumtoxinA (n = 30) injections into the nonparalyzed side. Adverse effects, facial symmetry, subjective satisfaction, and Facial Disability Index were assessed after 1 and 6 months.

RESULTS

The incidence of adverse effects was higher with abobotulinumtoxinA (93.3 percent versus 64.0 percent; p = 0.007). Clinical scores of the nonparalyzed side decreased after 1 month and increased again at 6 months, with no between-group differences. Scores of the paralyzed side were lower in the onabotulinumtoxinA group before treatment, but similar in both groups thereafter. The paralyzed side scores increased after 1 month, and at 6 months were still higher than the pretreatment scores in both groups. Subjective assessment improved at all time points compared with pretreatment scores and differed between the two groups only at 1 month, when the abobotulinumtoxinA group was a bit too paralyzed. The physical function and social/well-being function subscales of the Facial Disability Index did not differ between the two groups.

CONCLUSIONS

Both toxins efficiently reduced asymmetry in patients with facial palsy. Adverse effects were higher with abobotulinumtoxinA at an equivalence ratio of 1:3.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Employment of higher doses of botulinum toxin type A to reduce spasticity after stroke

Spasticity is a common disabling symptom for several neurological conditions. Botulinum toxin type A injection represents the gold standard treatment for focal spasticity with efficacy, reversibility, and low prevalence of complications. Current guidelines suggest a dose up to 600 units (U) of onabotulinumtoxinA/incobotulinumtoxinA or up to 1,500 U of abobotulinumtoxinA to treat post-stroke spasticity to avoid important adverse effects. However, recently, higher doses of botulinum toxin type A were employed, especially in case of upper and lower limb severe spasticity. With searches of US National Library of Medicine databases, we identified all studies published from December 1989 to July 2014 concerning the use of higher doses of this neurotoxin for spasticity treatment with at least a dose of 600 U of onabotulinumtoxinA and incobotulinumtoxinA or 1,800 U of abobotulinumtoxinA. The cumulative body of evidence coming from the eight studies selected suggested that higher doses of botulinum toxin type A appeared to be efficacious in reducing spasticity of the upper and lower limbs after stroke, with adverse effects generally mild. However, further investigations are needed to determine the safety and reproducibility in larger case series or randomized clinical trials of higher doses of botulinum toxin type A also after repeated injections.

Dysport and Botox at a ratio of 2.5:1 units in cervical dystonia: a double-blind, randomized study

We aimed to compare Dysport (abobotulinumtoxinA, Ipsen Biopharm, Slough, UK) and Botox (onabotulinumtoxinA, Allergan, Irvine, CA, USA) at a 2.5:1 ratio in the treatment of cervical dystonia (CD). A Dysport/Botox ratio of lower than 3:1 was suggested as a more appropriate conversion ratio, considering its higher efficacy and more frequent incidence of adverse effects not only in the treatment of CD but also in other focal movement disorders. A randomized, double-blind, multicenter, non-inferiority, two-period crossover study was done in CD, with a duration of at least 18 months. Patients were randomly assigned to treatment for the first period with Dysport or Botox, and they were followed up for 16 weeks after the injection. After a 4-week washout period, they were switched to the other formulation and then followed up for 16 weeks. The primary outcome was the changes in the Tsui scale between the baseline value and that at 1 month after each injection. A total of 103 patients were enrolled, and 94 completed the study. Mean changes in the Tsui scale between baseline and 4 weeks after each injection tended to favor Botox; however, this was not statistically significant (4.0 ± 3.9 points for the Dysport treatment vs. 4.8 ± 4.1 points for Botox; 95% confidence interval, −0.1-1.7; P = 0.091). The mean change of the Toronto western spasmodic torticollis rating scale score, the proportion of improvement in clinical global impression and patient global impression, and the incidences of adverse events were not significantly different between the two treatments. With regard to safety and efficacy, Dysport was not inferior to Botox in patients with CD at a conversion factor of 2.5:1. [http//clinicaltrial.gov: NCT00950664] © The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Botulinum toxin type A products are not interchangeable: a review of the evidence

Botulinum toxin type A (BoNTA) products are injectable biologic medications derived from Clostridium botulinum bacteria. Several different BoNTA products are marketed in various countries, and they are not interchangeable. Differences between products include manufacturing processes, formulations, and the assay methods used to determine units of biological activity. These differences result in a specific set of interactions between each BoNTA product and the tissue injected. Consequently, the products show differences in their in vivo profiles, including preclinical dose response curves and clinical dosing, efficacy, duration, and safety/adverse events. Most, but not all, published studies document these differences, suggesting that individual BoNTA products act differently depending on experimental and clinical conditions, and these differences may not always be predictable. Differentiation through regulatory approvals provides a measure of confidence in safety and efficacy at the specified doses for each approved indication. Moreover, the products differ in the amount of study to which they have been subjected, as evidenced by the number of publications in the peer-reviewed literature and the quantity and quality of clinical studies. Given that BoNTAs are potent biological products that meet important clinical needs, it is critical to recognize that their dosing and product performance are not interchangeable and each product should be used according to manufacturer guidelines.

Phase white matter signal abnormalities in patients with clinically isolated syndrome and other neurologic disorders

BACKGROUND AND PURPOSE

Identifying MRI biomarkers that can differentiate multiple sclerosis patients from other neurological disorders is a subject of intense research. Our aim was to investigate phase WM signal abnormalities for their presence, prevalence, location, and diagnostic value among patients with clinically isolated syndrome and other neurologic disorders and age-, sex-, and group-matched healthy controls.

MATERIALS AND METHODS

Forty-eight patients with clinically isolated syndrome and 30 patients with other neurologic diseases and a healthy control group (n = 47) were included in the study. Subjects were scanned at 3T by using SWI-filtered phase and T2WI, with WM signal abnormalities ≥3 mm being classified.

RESULTS

Patients with clinically isolated syndrome had significantly more phase and T2 WM signal abnormalities than healthy controls (P < .001). Phase WM signal abnormalities were more prevalent among patients with clinically isolated syndrome compared with patients with other neurologic disorders (4:1 ratio), whereas T2 WM signal abnormalities were more ubiquitous with a 2:1 ratio. The presence of phase WM signal abnormalities was sensitive for clinically isolated syndrome (70.8%) and achieved a moderate-to-high specificity for differentiating patients with clinically isolated syndrome and healthy controls, patients with other neurologic disorders, and patients with other neurologic disorders of other autoimmune origin (specificity, 70%-76.7%). Combining the presence of ≥2 phase lesions with the McDonald 2005 and 2010 criteria for dissemination in space improved the specificity (90%), but not the accuracy, in differentiating patients with clinically isolated syndrome from those with other neurologic disorders. In subanalyses among patients with clinically isolated syndrome who converted to clinically definite multiple sclerosis versus those who did not within a 3-year follow-up period, converters had significantly more phase (P = .008) but not T2 or T1 WM signal abnormalities.

CONCLUSIONS

Phase WM signal abnormalities are prevalent among patients with clinically isolated syndrome. The presence of (multiple) phase WM signal abnormalities tended to be more predictive of conversion to clinically definite multiple sclerosis and was specific in differentiating patients with clinically isolated syndrome and other neurologic disorders, compared with T2 WM signal abnormalities; however, the accuracy remains similar to that of the current McDonald criteria.

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.

Time course analysis of the effects of botulinum neurotoxin type A on pain and vasomotor responses evoked by glutamate injection into human temporalis muscles

The effect of botulinum neurotoxin type A (BoNTA) on glutamate-evoked temporalis muscle pain and vasomotor responses was investigated in healthy men and women over a 60 day time course. Subjects participated in a pre-BoNTA session where their responses to injection of glutamate (1 M, 0.2 mL) and saline (0.2 mL) into the temporalis muscles were assessed. On Day 1, BoNTA (5 U) was injected into one temporalis muscle and saline into the contralateral temporalis muscle, in a randomized order. Subjects then received intramuscular injections of glutamate (1 M, 0.2 mL) into the left and right temporalis muscles at 3 h and subsequently 7, 30 and 60 days post-injection of BoNTA. Pain intensity, pain area, and neurogenic inflammation (skin temperature and skin blood perfusion) were recorded. Prior to BoNTA treatment, glutamate evoked significantly greater pain and vasomotor reactions (P < 0.001) than saline. BoNTA significantly reduced glutamate-evoked pain intensity (P < 0.05), pain area (P < 0.01), skin blood perfusion (P < 0.05), and skin temperature (P < 0.001). The inhibitory effect of BoNTA was present at 3 h after injection, peaked after 7 days and returned to baseline by 60 days. Findings from the present study demonstrated a rapid action of BoNTA on glutamate-evoked pain and neurogenic inflammation, which is in line with animal studies.

Comparison between botulinum neurotoxin type A2 and type A1 by electrophysiological study in healthy individuals

Botulinum neurotoxin type A1 (BoNTs/A1) and type B (BoNT/B) have been used for treating hyperactive muscle contractions. In the present study, we compared the effect of botulinum neurotoxin subtype A2 (6.5 mouse LD50 units A2 neurotoxin, A2NTX) and onabotulinumtoxinA (10 mouse LD50 units BoNT/A1 product) by measuring the compound muscle action potentials (CMAPs) before and after administration. In total, 8 healthy subjects were examined in the present study. A2NTX was injected into the extensor digitorum brevis (EDB) muscle, followed by onabotulinumtoxinA injection into the contralateral EDB muscle after 16 weeks. The CMAP amplitudes from the EDB, abductor hallucis (AH), and abductor digiti minimi pedis (ADM) muscles were measured after each BoNT injection on days 1, 3, 7, 14, 28, 56, 84, and 112 to assess the effect of the toxin. On day 14, both A2NTX and onabotulinumtoxinA produced an approximately 70% decline in EDB CMAP amplitude compared to the baseline values; significant reduction of the CMAP continued through day 112. The CMAP amplitudes from neighboring muscles (AH and ADM) remained intact throughout the study period, except for a slight but significant drop at day 28 after onabotulinumtoxinA injection compared to A2NTX. The current findings indicate that small doses (6.5 units and 10 units) of A2NTX and onabotulinumtoxinA have at least comparable onset and duration of action, although similar clinical effects were obtained with lower dose using A2NTX.

Treatment of dystonia

Selecting the appropriate treatment for dystonia begins with proper classification of disease based on age, distribution, and underlying etiology. The therapies available for dystonia include oral medications, botulinum toxin, and surgical procedures. Oral medications are generally reserved for generalized and segmental dystonia. Botulinum toxin revolutionized the treatment of focal dystonia when it was introduced for therapeutic purposes in the 1980s. Surgical procedures are available for medication-refractory dystonia, markedly affecting an individual's quality of life.

Evidence-based review and assessment of botulinum neurotoxin for the treatment of movement disorders

Botulinum neurotoxin (BoNT) can be injected to achieve therapeutic benefit across a large range of clinical conditions. To assess the efficacy and safety of BoNT injections for the treatment of certain movement disorders, including blepharospasm, hemifacial spasm, oromandibular dystonia, cervical dystonia, focal limb dystonias, laryngeal dystonia, tics, and essential tremor, an expert panel reviewed evidence from the published literature. Data sources included English-language studies identified via MEDLINE, EMBASE, CINAHL, Current Contents, and the Cochrane Central Register of Controlled Trials. Evidence tables generated in the 2008 Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology (AAN) review of the use of BoNT for movement disorders were also reviewed and updated. The panel evaluated evidence at several levels, supporting BoNT as a class, the serotypes BoNT-A and BoNT-B, as well as the four individual commercially available formulations: abobotulinumtoxinA (A/Abo), onabotulinumtoxinA (A/Ona), incobotulinumtoxinA (A/Inco), and rimabotulinumtoxinB (B/Rima). The panel ultimately made recommendations for each therapeutic indication, based upon the strength of clinical evidence and following the AAN classification scale. For the treatment of blepharospasm, the evidence supported a Level A recommendation for BoNT-A, A/Inco, and A/Ona; a Level B recommendation for A/Abo; and a Level U recommendation for B/Rima. For hemifacial spasm, the evidence supported a Level B recommendation for BoNT-A and A/Ona, a Level C recommendation for A/Abo, and a Level U recommendation for A/Inco and B/Rima. For the treatment of oromandibular dystonia, the evidence supported a Level C recommendation for BoNT-A, A/Abo, and A/Ona, and a Level U recommendation for A/Inco and B/Rima. For the treatment of cervical dystonia, the published evidence supported a Level A recommendation for all four BoNT formulations. For limb dystonia, the available evidence supported a Level B recommendation for both A/Abo and A/Ona, but no published studies were identified for A/Inco or B/Rima, resulting in a Level U recommendation for these two formulations. For adductor laryngeal dystonia, evidence supported a Level C recommendation for the use of A/Ona, but a Level U recommendation was warranted for B/Rima, A/Abo, and A/Inco. For the treatment of focal tics, a Level U recommendation was warranted at this time for all four formulations. For the treatment of tremor, the published evidence supported a level B recommendation for A/Ona, but no published studies were identified for A/Abo, A/Inco, or B/Rima, warranting a Level U recommendation for these three formulations. Further research is needed to address evidence gaps and to evaluate BoNT formulations where currently there is insufficient or conflicting clinical data.

Botulinum toxin for the treatment of movement disorders

After botulinum toxin was initially used to treat strabismus in the 1970s, others started using it to treat movement disorders including blepharospasm, hemifacial spasm, cervical dystonia, spasmodic dysphonia, and oromandibular dystonia. It was discovered that botulinum toxin can be an effective treatment for focal movement disorders with limited side effects. Over the past three decades, various formulations of botulinum toxin have been developed and the therapeutic use of these toxins has expanded in movement disorders and beyond. We review the history and mechanism of action of botulinum toxin, as well as describe different formulations available and their potential therapeutic uses in movement disorders.

Treatment of focal dystonia

OPINION STATEMENT

Dystonia is characterized by repetitive twisting movements or abnormal postures due to involuntary muscle activity. When limited to a single body region it is called focal dystonia. Examples of focal dystonia include cervical dystonia (neck), blepharospasm (eyes), oromandibular dystonia, focal limb dystonia, and spasmodic dysphonia, which are discussed here. Once the diagnosis is established, the therapeutic plan is discussed with the patients. They are informed that there is no cure for dystonia and treatment is symptomatic. The main therapeutic option for treating focal dystonias is botulinum toxin (BoNT). There have been several attempts to characterize the procedure, the type of toxin, dosage, techniques, and combination with physical measures in each of the focal dystonia forms. The general treatment principles are similar. The affected muscles are injected at muscle sites based on evidence and experience using standard dosages based on the type of toxin used. The injections are repeated after 3 to 6 months based on the individual response duration. In the uncommon event of nonresponse with BoNT, the dose and site are reassessed. Oral drug treatment could be considered as an additional option. Once the condition is thought to be medically refractory, the opinion from the deep brain stimulation (DBS) team for the suitability of the patient for DBS is taken. The successful use of DBS in cervical dystonia has led to increased acceptance for trial in other forms of focal dystonias. DBS surgery in focal dystonias other than cervical is, however, still experimental. The patients may be offered the surgery with adequate explanation of the risks and benefits. Patient education and directing the patients towards dystonia support groups and relevant websites that provide scientific information may be useful for long-term compliance and benefit.

Diffusion of botulinum toxins

BACKGROUND

It is generally agreed that diffusion of botulinum toxin occurs, but the extent of the spread and its clinical importance are disputed. Many factors have been suggested to play a role but which have the most clinical relevance is a subject of much discussion.

METHODS

This review discusses the variables affecting diffusion, including protein composition and molecular size as well as injection factors (e.g., volume, dose, injection method). It also discusses data on diffusion from comparative studies in animal models and human clinical trials that illustrate differences between the available botulinum toxin products (onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and rimabotulinumtoxinB).

RESULTS

Neither molecular weight nor the presence of complexing proteins appears to affect diffusion; however, injection volume, concentration, and dose all play roles and are modifiable. Both animal and human studies show that botulinum toxin products are not interchangeable, and that some products are associated with greater diffusion and higher rates of diffusion-related adverse events than others.

DISCUSSION

Each of the botulinum toxins is a unique pharmacologic entity. A working knowledge of the different serotypes is essential to avoid unwanted diffusion-related adverse events. In addition, clinicians should be aware that the factors influencing diffusion may range from properties intrinsic to the drug to accurate muscle selection as well as dilution, volume, and dose injected.

Current and future medical treatment in primary dystonia

Dystonia is a hyperkinetic movement disorder, characterized by involuntary and sustained contractions of opposing muscles causing twisting movements and abnormal postures. It is often a disabling disorder that has a significant impact on physical and psychosocial wellbeing. The medical therapeutic armamentarium used in practice is quite extensive, but for many of these interventions formal proof of efficacy is lacking. Exceptions are the use of botulinum toxin in patients with cervical dystonia, some forms of cranial dystonia (in particular, blepharospasm) and writer's cramp; deep brain stimulation of the pallidum in generalized and segmental dystonia; and high-dose trihexyphenidyl in young patients with segmental and generalized dystonia. In order to move this field forward, we not only need better trials that examine the effect of current treatment interventions, but also a further understanding of the pathophysiology of dystonia as a first step to design and test new therapies that are targeted at the underlying biologic and neurophysiologic mechanisms.

Muscle selection for treatment of cervical dystonia with botulinum toxin--a systematic review

RATIONALE

Cervical dystonia, also called spasmodic torticollis, is the most common form of (primary) dystonia. Intramuscular injections with botulinum toxin are the first line of treatment for cervical dystonia. To optimise the treatment response to botulinum toxin correct muscles should be selected. Clinical evaluation is important for muscle selection but the value of additional tests to identify dystonic muscles remains unclear.

OBJECTIVE

To evaluate all relevant literature regarding the best approach to select dystonic muscles for treatment with botulinum toxin.

METHODS

We conducted a systematic review of studies that had investigated methods of selecting muscles for treatment with botulinum toxin. In addition, we compared all prospective botulinum toxin trials using either clinical evaluation or polymyographic electromyography for muscle selection.

RESULTS

Forty relevant studies were included and polymyographic electromyography recordings were most often employed. In several studies, polymyographic electromyography revealed a different pattern of muscle involvement compared to that found during clinical evaluation. In one randomized controlled trial polymyographic electromyography significantly improved the outcome of botulinum toxin treatment. A limited number of studies used positron emission tomography -computed tomography imaging or frequency analysis of the electromyography signal to identify dystonic muscles but their effect on the outcome of treatment has never been studied.

CONCLUSION

Polymyographic electromyography may improve the outcome of botulinum toxin treatment in cervical dystonia, but evidence is limited and larger studies are needed.

Botulinum toxin effects on gasatrocnemius strength and plantar pressure in diabetics with peripheral neuropathy and forefoot ulceration

BACKGROUND

High forefoot plantar pressure is associated with plantar ulcers in people with diabetes and peripheral neuropathy. The purpose of this pilot study was to determine the safety and efficacy of botulinum toxin A injected into the gastrocnemius-soleus muscles to reduce muscle strength and plantar pressure.

METHODS

This double blind, randomized clinical trial studied 17 people with diabetes mellitus, peripheral neuropathy and a forefoot plantar ulcer. Subjects were randomized into one of three groups receiving gastrocnemius-soleus muscle injections on the involved side with; 1) Saline (n = 5, weight =99± 21 kg), 2) 200-units of Botox® (n = 7, weight = 101± 5 kg), or 3) 300-units of Botox® (n = 5, weight = 129± 22 kg). Botox® dose was converted to units/kg, the majority received between 1.9 and 2.4 units/kg (n = 11) and one 3.2 units/kg. Plantarflexor peak torque and forefoot peak plantar pressure were quantified prior and 2 weeks post-injection.

RESULTS

There were no complications from the injections. Plantarflexor peak torque on the involved side increased in the placebo and 300 groups (3± 4 Nm and 6± 10 Nm, respectively) and decreased -8± 11 Nm in the 200 group. There was no relationship between units/kg of Botox® for each subject and change in plantarflexor peak torque. Forefoot peak plantar pressure did not change in the placebo and 300 groups (0± 11 and 0± 5 N/cm(2), respectively) and decreased -4± 16 N/cm2 (4%) for the 200 group.

CONCLUSION

There were no adverse events associated with the Botox® injections. This study was unable to determine the dose to consistently reduce plantarflexor strength and forefoot plantar pressure. Additional research is needed to investigate diabetes mellitus specific physiological changes and their impact of BoNT-A effectiveness in order to guide appropriate dosing.

Botulinum toxins in the treatment of primary focal dystonias

Focal dystonia, such as cervical dystonia, blepharospasm, oromandibular dystonia, laryngeal dystonia, and limb dystonia, is often observed in adult-onset primary dystonia syndromes that affect a specific area of the body and tend to have little or no spread. This review will examine the past, present, and future approaches to the treatment of focal dystonia. Botulinum toxin (BoNT) has emerged as the treatment of choice for the majority of focal dystonias. Currently four products are widely available commercially, three of BoNT/A type and one of BoNT/B type. Each has important pharmacological differences that give rise to markedly different dosing recommendations. The four approved BoNTs are safe and effective for treating focal dystonias, including long-term treatment. Adverse events are limited and transient and, for the most part, mild in severity. Potential problems with the use of BoNT agents are diffusion and neutralizing antibody formation; the latter can lead to treatment resistance. Because each BoNT product is developed from distinct purification and manufacturing procedures and has varying toxin complex size and structures, physicians need to be aware of these differences when choosing an agent.

A new treatment for focal dystonias: incobotulinumtoxinA (Xeomin®), a botulinum neurotoxin type A free from complexing proteins

Dystonia is a movement disorder of uncertain pathogenesis that is characterized by involuntary and inappropriate muscle contractions which cause sustained abnormal postures and movements of multiple or single (focal) body regions. The most common focal dystonias are cervical dystonia (CD) and blepharospasm (BSP). The first-line recommended treatment for CD and BSP is injection with botulinum toxin (BoNT), of which two serotypes are available: BoNT type A (BoNT/A) and BoNT type B (BoNT/B). Conventional BoNT formulations include inactive complexing proteins, which may increase the risk for antigenicity, possibly leading to treatment failure. IncobotulinumtoxinA (Xeomin(®); Merz Pharmaceuticals GmbH, Frankfurt, Germany) is a BoNT/A agent that has been recently Food and Drug Administration-approved for the treatment of adults with CD and adults with BSP previously treated with onabotulinumtoxinA (Botox(®); Allergen, Inc, Irvine, CA) - a conventional BoNT/A. IncobotulinumtoxinA is the only BoNT product that is free of complexing proteins. The necessity of complexing proteins for the effectiveness of botulinum toxin treatment has been challenged by preclinical and clinical studies with incobotulinumtoxinA. These studies have also suggested that incobotulinumtoxinA is associated with a lower risk for stimulating antibody formation than onabotulinumtoxinA. In phase 3 noninferiority trials, incobotulinumtoxinA demonstrated significant improvements in CD and BSP symptoms in both primary and secondary measures, compared with baseline, and met criteria for noninferiority versus onabotulinumtoxinA. In placebo-controlled trials, incobotulinumtoxinA also significantly improved the symptoms of CD and BSP, with robust outcomes in both primary and secondary measures. The use of incobotulinumtoxinA has been well tolerated in all trials, with an adverse event profile similar to that of onabotulinumtoxinA. Based on these data, incobotulinumtoxinA is a safe and effective BoNT/A for the treatment of CD and BSP, and may pose a lower risk for immunogenicity leading to treatment failure compared with other available BoNT agents. This paper reviews the treatment of focal dystonias with BoNTs, in particular, incobotulinumtoxinA. Controlled trials from the existing incobotulinumtoxinA literature are summarized.

Treatment of refractory pain with botulinum toxins--an evidence-based review

OBJECTIVES

To provide updated information on the role of botulinum toxins in the treatment of refractory pain based on prospective, randomized, double-blind, placebo-controlled studies. DESIGN OF THE REVIEW: Class I and class II articles were searched online through PubMed (1966 to the end of January 2011) and OvidSP including ahead-of-print manuscripts.

RESULTS

Level A evidence (two or more class I studies-established efficacy): pain of cervical dystonia, chronic migraine, and chronic lateral epicondylitis. Level B evidence (one class I or two class II studies-probably effective and recommended): post-herpetic neuralgia, post-traumatic neuralgia, pain of plantar fasciitis, piriformis syndrome, and pain in total knee arthroplasty. Level C evidence (one class II study-possibly effective, may be used at discretion of clinician): allodynia of diabetic neuropathy, chronic low back pain, painful knee osteoarthritis, anterior knee pain with vastus lateralis imbalance, pelvic pain, post-operative pain in children with cerebral palsy after adductor hip release surgery, post-operative pain after mastectomy, and sphincter spasms and pain after hemorrhoidectomy. Level U evidence (efficacy not proven due to diverse class I and II results): myofascial pain syndrome and chronic daily headaches. Studies in episodic migraine and tension headaches have shown treatment failure (level A-negative).

CONCLUSION

Evidence-based data indicate that administration of botulinum toxin in several human conditions can alleviate refractory pain. The problems with some study designs and toxin dosage are critically reviewed.

Noncosmetic periocular therapeutic applications of botulinum toxin

Botulinum toxin blocks acetylcholine release at the neuromuscular junction. The drug which was initially found to be useful in the treatment of strabismus has been extremely effective in the treatment of variety of conditions, both cosmetic and noncosmetic. Some of the noncosmetic uses of botulinum toxin applications include treatment of spastic facial dystonias, temporary treatment of idiopathic or thyroid dysfunction-induced upper eyelid retraction, suppression of undesired hyperlacrimation, induction of temporary ptosis by chemodenervation in facial paralysis, and correction of lower eyelid spastic entropion. Additional periocular uses include control of synchronic eyelid and extraocular muscle movements after aberrant regeneration of cranial nerve palsies. Cosmetic effects of botulinum toxin were discovered accidentally during treatments of facial dystonias. Some of the emerging nonperiocular application for the drug includes treatment of hyperhidrosis, migraine, tension-type headaches, and paralytic spasticity. Some of the undesired side effects of periocular applications of botulinum toxin inlcude ecchymosis, rash, hematoma, headache, flu-like symptoms, nausea, dizziness, loss of facial expression, lower eyelid laxity, dermatochalasis, ectropion, epiphora, eyebrow and eyelid ptosis, lagophthalmos, keratitis sicca, and diplopia.

Retrospective evaluation of the dose equivalence of Botox(®) and Dysport (®) in the management of blepharospasm and hemifacial spasm: a novel paradigm for a never ending story

Botox(®) and Dysport(®) are the preparations of botulinum neurotoxin most widely used for therapeutic purposes. Several studies have addressed the topic of the equivalency ratio (D/B ratio) to be used in clinical practice and whether a reliable value exists is still a matter of debate. To this purpose, we ideated a novel paradigm by retrospectively examining the patients affected by hemifacial spasm and blepharospasm. We compared the pairs of treatments with a switch from one brand to the other undergone by the same patient in consecutive sessions with overlapping clinical outcome. Out of 2006 treatments, we found 51 treatment pairs. D/B ratio was extremely variable (range 1.2-13.3) and in most cases (65%) it was between 1:3 and 1:5. In conclusion, even if the 1:4 ratio might be reliable for clinical purpose, a true bioequivalence between Dysport(®) and Botox(®) might not exist due to the intrinsic difference in their pharmacokinetic properties.

Profile of Xeomin® (incobotulinumtoxinA) for the treatment of blepharospasm

Even though conventional botulinum neurotoxin (BoNT) products have shown successful treatment results in patients with benign blepharospasm (BEB), the main, potential long-term side effect of BoNT use is the development of immunologic resistance due to the production of neutralizing antibody to the neurotoxin after repeated injections. Xeomin^® (incobotulinumtoxinA), a unique botulinum neurotoxin type A (BoNT/A) drug free of complexing proteins otherwise contained in all conventional BoNT/A drugs, was recently approved by US Food and Drug Administration for the treatment of cervical dystonia or blepharospasm in adults. The newly approved BoNT/A drug may overcome this limitation of previous conventional products, since it contains pure neurotoxin (150 kDa) through a manufacturing process that separates it from complexing proteins such as hemagglutinins produced by fermentation of Clostridium botulinum. Many studies have also shown that Xeomin^® has the same efficacy and safety profile as complexing protein-containing products such as Botox^® and is exchangeable with Botox^® using a simple 1:1 conversion ratio. Xeomin^® represents a new treatment option for the repeated treatment of patients with blepharospasm in that it may reduce antibody-induced therapy failure. But, long-term comparative trials in naïve patients between Xeomin^® and conventional BoNT/A drugs are required to confirm the low immunogenicity of Xeomin^®.

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.

Systemic weakness after therapeutic injections of botulinum toxin a: a case series and review of the literature

The use of intramuscular injections of Botulinum neurotoxin A (BoNT-A) is common in the treatment of hypertonicity and movement disorders. Although most side effects are mild, systemic effects, manifested by generalized weakness distant from the site of injection, have been reported. Previously reported occurrences are discussed, and 3 new cases of patients, who developed systemic weakness after administration of BoNT-A (Botox), despite having tolerated similar injections on several previous occasions, are presented. A review of the literature and reported cases indicate that risk of developing systemic effects does not seem to be related to dose based on body weight. It may be more likely that risk for systemic effects is related to total injection dose and injection frequency. The results of our 3 patients would indicate that injections of greater than 600 units of Botox with follow-up injections occurring every 3 months may lead to an increased risk. We would recommend careful consideration of reinjection frequency if injections of greater than 600 units of Botox are given. Reduction in systemic side effects may occur if reinjection frequency occurs in intervals of 4 months or greater in these individuals.

The efficacy of botulinum toxin type A in managing chronic musculoskeletal pain: a systematic review and meta analysis

BACKGROUND

Botulinum toxin type A (BoNTA) is a neurotoxin that acts by inhibiting the release of neurotransmitters acetylcholine at neuromuscular junctions, thus reducing muscular contractions. Recent evidence suggests that BoNTA can reduce nociceptive activities of sensory neurons in animal models by inhibiting release of certain neuropeptides. Despite the therapeutic benefit of BoNTA in alleviating painful muscle spasms, its efficacy in other musculoskeletal pain conditions is less clear.

OBJECTIVE

We aim to examine the efficacy of BoNTA in reducing chronic musculoskeletal pain.

METHODS

Studies for inclusion in our report were identified using MEDLINE, EMBASE, PUBMED, Cochrane Central Register of Controlled Trials, CINAHL, and reference lists of relevant articles. Studies were considered eligible for inclusion if they were randomized controlled trials (RCTs), evaluating the efficacy of BoNTA injections in pain reduction. All studies were assessed and data were abstracted independently by paired reviewers. The outcome measures were baseline and final pain scores as assessed by the patients. The internal validity of trials was assessed with the Jadad scale. Disagreements were resolved through discussions.

MAIN RESULTS

Twenty-one studies were included in the systematic review and 15 of them were included in the final meta-analysis. There was a total of 706 patients in the meta-analysis, represented from trials of plantar fasciitis (n = 1), tennis elbow (n = 2), shoulder pain (n = 1), whiplash (n = 3), and myofascial pain (n = 8). Overall, there was a small to moderate pain reduction among BoNTA patients when compared to control (SMD = -0.27, 95% CI: -0.44 to -0.11). When the results were analyzed in subgroups, only tennis elbow (SMD = -0.44, 95% CI: -0.86 to -0.01) and plantar fasciitis (SMD = -1.04, 95% CI: -1.68 to -0.40) demonstrated significant pain relief. Although not in the meta-analysis, one back pain study also demonstrated positive results for BoNTA. Lastly, BoNTA was effective when used at ≥ 25 units per anatomical site or after a period ≥ 5 weeks.

CONCLUSION

In our meta-analysis, BoNTA had a small to moderate analgesic effect in chronic musculoskeletal pain conditions. It was particularly effective in plantar fasciitis, tennis elbow, and back pain, but not in whiplash or shoulder pain patients. However, more evidence is required before definitive conclusions can be drawn. On the other hand, there is convincing evidence that BoNTA lacks strong analgesic effects in patients with myofascial pain syndrome. A general dose-dependent and temporal response with BoNTA injections was also observed.

Botulinum toxin injection in neurogenic thoracic outlet syndrome: results and experience using a ultrasound-guided approach

OBJECTIVE

The purpose of this study was to describe the technique, complications, and rate of symptom relief after ultrasound-guided botulinum toxin injection in subjects with suspected neurogenic thoracic outlet syndrome (NTOS).

MATERIALS AND METHODS

This study was IRB-approved and followed HIPPA guidelines. Subjects investigated for NTOS were identified via retrospective review of medical records. Procedures included botulinum toxin injections of the anterior scalene, pectoralis minor, and subclavius muscles performed under real-time ultrasound guidance. Technical success was defined as satisfactory muscle identification, intramuscular needle placement, and intramuscular delivery of medication. Follow-up was performed to determine procedure-related complications and therapy response using a binary assessment and modified visual analogue scale (VAS).

RESULTS

Forty-one subjects with suspected NTOS underwent a total of 92 injections (58 anterior scalene, 33 pectoralis minor, and 1 subclavius muscle). Technical success was achieved in all procedures. No complications occurred. Symptom improvement occurred after 69% of procedures. The VAS before and after the procedure changed from 7.1 to 2.8 (P < 0.0001) respectively. The mean time to symptom improvement and duration of symptom improvement were 12 and 31 days respectively.

CONCLUSION

Botulinum toxin injection under ultrasound guidance is a safe and well-tolerated procedure with a satisfactory rate of temporary symptom relief in subjects with suspected NTOS.

Botulinum toxin

Botulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C₁, C₂, D, E, F and G). All serotypes interfere with neural transmission by blocking the release of acetylcholine, the principal neurotransmitter at the neuromuscular junction, causing muscle paralysis. The weakness induced by injection with botulinum toxin A usually lasts about three months. Botulinum toxins now play a very significant role in the management of a wide variety of medical conditions, especially strabismus and focal dystonias, hemifacial spasm, and various spastic movement disorders, headaches, hypersalivation, hyperhidrosis, and some chronic conditions that respond only partially to medical treatment. The list of possible new indications is rapidly expanding. The cosmetological applications include correction of lines, creases and wrinkling all over the face, chin, neck, and chest to dermatological applications such as hyperhidrosis. Injections with botulinum toxin are generally well tolerated and side effects are few. A precise knowledge and understanding of the functional anatomy of the mimetic muscles is absolutely necessary to correctly use botulinum toxins in clinical practice.

Botulinum toxin: examining duration of effect in facial aesthetic applications

Patient satisfaction with botulinum toxin treatment is a key success factor in aesthetic procedures and is governed by the interaction of numerous variables. Duration of effect is important because it influences retreatment intervals as well as affecting cost and convenience to the patient. In order to review the evidence on the duration of benefit associated with various commercial formulations of botulinum toxin, MEDLINE was searched using the following terms: 'botulinum' and 'duration'/'retreatment' (limits: 'clinical trials,' 'meta-analyses,' 'English'). I also searched my existing reference files, reference lists of identified articles, and meeting/conference abstracts to ensure completeness. The focus was on clinical medicine and aesthetic trials. To be eligible for the analysis, studies had to include efficacy assessments at multiple timepoints. To estimate duration of benefit, the following outcomes were examined and summarized: responder rates, mean wrinkle severity scores at various timepoints (with or without changes from baseline), and relapse rates. Duration at both repose and maximum attempted muscle contraction was considered when provided. Where possible, duration was assessed by formulation and dose. The initial search yielded 164 articles. Of these, 35 included an adequate measure of duration in aesthetic indications. The majority of these (22) were on the glabellar area. Study designs and endpoints were highly heterogeneous, and duration of effect varied between studies. Several studies with the BOTOX Cosmetic (onabotulinumtoxinA; Allergan, Inc., Irvine, CA, USA) formulation of botulinum toxin type A (BoNTA) included relapse rates, defined conservatively as return to baseline levels of line severity for two consecutive visits approximately 30 days apart (at repose and maximum contraction). In these studies, duration of effect ranged from 3 to 5 months in female patients and from 4 to 6 months in male patients. Individual patients had longer durations of response. Across all studies providing relapse rates, most patients relapsed by 6 months. In studies assessing patient satisfaction, satisfaction remained high throughout the duration of the studies ( approximately 4 months). With the Dysport formulation (abobotulinumtoxinA, clostridium botulinum type A toxin-hemagglutinin complex; Ipsen Biopharm Ltd, Wrexham, England), retreatment intervals were estimated at a mean of 3.9 months (median = 3.3 months). These results were consistent with responder rates from another Dysport study in which the active treatment differed from placebo at 3 but not 4 months. A single comparative study demonstrated that the proportion of patients relapsing at week 16 was 23% (95% CI 11.5, 41.6) in the BOTOX Cosmetic group as compared with 40% (95% CI 25.2, 60.1) in the Dysport group. Myobloc (rimabotulinumtoxinB, botulinum toxin type B; Solstice Neurosciences, Inc., South San Francisco, CA, USA) was associated with shorter durations of action (2-3 months). Data from facial areas other than the glabella, although more limited, supported a duration of at least 3-4 months. The addition of BoNTA to dermal fillers or light/laser therapy appeared to increase the degree of effect. Repeated BoNTA treatments may prolong duration of effect or potentiate the effect. In conclusion, patients can expect treatments to last > or =3 months but often as many as 4-5 months depending on the facial area, dose, and formulation. Additional research should help clarify the impact of age, baseline rhytid severity, patient sex, repeated treatments, and combination treatment on longevity of effect.

[Different botulinum toxins and their specifications]

Botulinum neurotoxin A was the first developed for therapeutic and then esthetic uses, Botox first and then Dysport. These two products differ on a few points, explaining their nonequivalence of units: American and British tests of the mouse LD50 units based on solutions that were not identical and 500microg vs 150microg serum albumin dose in the excipient. The neurotoxin- accessory protein complexes were also different: 900 kDa homogeneous for Botox, 500 kDa heterogeneous for Dysport, giving greater diffusion for Dysport, but this is under debate and could result from an excessive conversion ratio. Clinical comparative studies, often with weak methodology, have defined an ideal ratio between these two products, guaranteeing efficacy, but without an overly pronounced diffusion. In the first publications for neurological and ophthalmological indications, the conversion ratio between Dysport and Botox was high, 4:1, and sometimes higher. However, today, particularly for cosmetic indications, the trend is toward a much lower ratio, 2.5:1, or perhaps less for dyshidrosis. This lower ratio has an economic incidence: Dysport is less expensive and therefore more competitive. The price of Dysport's cosmetic product, Azzalure, compared to the price of Vistabel, which is Botox's cosmetic presentation, has not yet been defined in France. The other A toxins, Xeomin, and the Asian toxins, MyoBloc (botulinum toxin type B), tested compared to Botox, have a slightly lower efficacy.

Cervical dystonia

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

Use of botulinum toxin in voice restoration after laryngectomy

BACKGROUND

Following laryngectomy, a distinct population of patients fails to achieve successful tracheoesophageal voice. These patients' voices range from strained and effortful to none at all. Such patients may present with severe hypertonicity or spasm of the pharyngoesophageal segment. Botulinum toxin has been used to chemically denervate the pharyngeal musculature, and is an alternative to invasive surgical procedures. The aim of this article is to review the evidence for using botulinum toxin to achieve an improvement in post-laryngectomy voice.

METHODS

A Medline literature review (1966 to January 2009) and a search of the Cochrane database were performed. Foreign language articles and those not pertaining to post-laryngectomy voice restoration were excluded.

RESULTS

Nine articles reporting a total of 134 patients were identified. Although there were differences in the outcome measures used, objective improvement in voice production occurred in between 70 and 100 per cent of cases.

CONCLUSION

Botulinum toxin can be used as a safe and cost-effective treatment in patients with confirmed pharyngoesophageal segment hypertonicity and/or spasm following laryngectomy, to obtain an improvement in voice quality.

Dose equivalence of two commercial preparations of botulinum neurotoxin type A: time for a reassessment?

BACKGROUND

The units of different preparations of botulinum neurotoxin type A (BoNT-A) have different potencies, and dosing recommendations for each product are not interchangeable. Historically, there has been debate concerning the dose-equivalence ratio that should be used in clinical practice.

METHODS

Published evidence was considered to establish an appropriate dose-conversion ratio for the two main commercially available preparations of BoNT-A--Dysport (Dp) and Botox (Bx).

RESULTS

Four key areas of evidence were identified: nonclinical and preclinical studies; studies exploring the diffusion characteristics and effects of complexing proteins; comparative experimental data from human studies; and clinical studies. Nonclinical data indicate that the principal reasons for differences in unit potency between the two products are dilution artefacts in the mouse assay. Use of saline as a diluent, at high dilutions, results in significant loss of potency in the Bx assay, whereas use of gelatin phosphate buffer in the Dp assay procedure protects the toxin during dilution. The published data on mouse assays show a Dp : Bx unit ratio range of 2.3-2.5 : 1 in saline and 1.8-3.2 : 1 in gelatin phosphate buffer. Data indicate that complexing proteins or size of the complex, which is highly pH sensitive, play no role in toxin diffusion and that Dp and Bx have similar diffusion characteristics when used at comparable doses. Randomized, controlled clinical studies indicate that 3 : 1 is more appropriate than 4 : 1, but the two products are not equivalent at this ratio. Comparative human experimental studies using the extensor digitorum brevis test, facial lines and anhidrotic action halo tests support dose-conversion ratios less than 3 : 1.

LIMITATIONS

Data comparing dose equivalence ratios from the non-clinical setting should be extrapolated into the clinical setting with some caution.

CONCLUSIONS

Dose-conversion ratios between Dp and Bx of 4 : 1 and greater are not supported by the recent literature.

Respective potencies of Botox and Dysport in a human skin model: a randomized, double-blind study

Mouse units used to quantify the activity of botulinum A toxin preparations are not equivalent and issues concerning efficacy and safety remain with regard to their respective potencies and diffusion qualities in human tissue. We compared the effects of Botox (BOT) and Dysport (DYS) in different doses and dilutions in a human skin model. Eighteen (8 women, 10 men) healthy volunteers, aged 28.4 years +/- 5.7 years were injected intradermally with pure saline, BOT and DYS at 16 points in the abdomen in random order and in a double-blind condition, using two conversion ratios (1:3 and 1:4) and three different dilution schemes. For an objective outcome, the Ninhydrin sweat test was used to compare the anhidrotic areas. Both preparations showed a linear dose and dilution relationship with similar variances of responses for anhidrosis and hypohidrosis, indicating the same reliability of response. The dose equivalence conversion ratios (BOT: DYS) were 1:1.3 for anhidrosis and 1:1.6 for hypohidrosis (1:1.1-1.5 and 1:1.4-1.8 95% confidence intervals). The diffusion characteristics of both products were similar. A dose equivalence factor of more than 1:2 (BOT:DYS) is not supported by these objective and reproducible data.

Lyme neuroborreliosis: manifestations of a rapidly emerging zoonosis

Lyme disease has a worldwide distribution and is the most common vector-borne disease in the United States. Incidence, clinical manifestations, and presentations vary by geography, season, and recreational habits. Lyme neuroborreliosis (LNB) is neurologic involvement secondary to systemic infection by the spirochete Borrelia burgdorferi in the United States and by Borrelia garinii or Borrelia afzelii species in Europe. Enhanced awareness of the clinical presentation of Lyme disease allows inclusion of LNB in the imaging differential diagnosis of facial neuritis, multiple enhancing cranial nerves, enhancing noncompressive radiculitis, and pediatric leptomeningitis with white matter hyperintensities on MR imaging. The MR imaging white matter appearance of successfully treated LNB and multiple sclerosis display sufficient similarity to suggest a common autoimmune pathogenesis for both. This review highlights differences in the epidemiology, clinical manifestations, diagnosis, and management of Lyme disease in the United States, Europe, and Asia, with an emphasis on neurologic manifestations and neuroimaging.

Undesirable distant effects following botulinum toxin type a injection

OBJECTIVES

To study the incidence of clinical signs linked to botulinum toxin type A (BoNTA) spread from the injection site.

METHODS

Single-center, retrospective, cohort study. All patients who received BoNTA injections for spasticity treatment were assessed 1 month postinjection. Adverse effects indicative of BoNTA treatment were systematically sought. Any patient with adverse effects possibly due to BoNTA spread underwent further clinical examination and single-fiber electromyography. One patient underwent neuromuscular biopsy.

RESULTS

Between January and September 2005, 266 BoNTA injection sessions (187 patients) were performed (233 BOTOX, 33 Dysport). Five patients presented with clinical signs of toxin spread. Four of these underwent single-fiber electromyography, which showed increased jitter. Neuromuscular biopsy detected signs of recent denervation without signs of reinnervation.

CONCLUSIONS

Diffusion diagnosis of BoNTA from the injection site depends on clinical, temporal, and electromyographic factors. Clinical expression of spread varies widely, with mechanisms remaining largely unknown, and further prospective, randomized clinical trials are required.

Clinical comparisons of botulinum neurotoxin formulations

BACKGROUND

The expanding uses of botulinum neurotoxin (BoNT) for a growing number of clinical indications, including cervical and other dystonias, adult and childhood spasticity, and hyperhidrosis, in conjunction with the emergence of new formulations of BoNT, prompt discussion of the differences in formulations, serotypes, and indications for different neurologic diseases.

REVIEW SUMMARY

This review will evaluate evidence from preclinical studies, prospective treatment studies, and direct comparative trials to discuss the differences among BoNTs and the clinical implications of using these different drugs. Data from these sources indicate that formulations of BoNT are distinct; even the same serotype formulations of BoNT serotype A have different molecular structures and sizes and therapeutic indices (reflected in different safety and efficacy profiles).

CONCLUSION

Taken together, these findings confirm that the different BoNT serotypes, including the different BoNTA formulations, are distinct therapeutic entities.

Botulinum neurotoxins in the treatment of refractory pain

The proper management of pain is a critical issue in the practice of medicine. Despite the availability of a large number of analgesic medications, management of pain that is refractory to conventional treatments remains a challenge for both clinicians and surgeons. Botulinum neurotoxin (BoNT) has recently emerged as a potential novel approach to control pain. Animal studies have revealed a number of mechanisms by which BoNTs can influence and alleviate chronic pain, including inhibition of pain peptide release from nerve terminals and sensory ganglia, anti-inflammatory and antiglutaminergic effects, reduction of sympathetic neural discharge, and inhibition of muscle spindle discharge. In humans, prospective, placebo-controlled, double-blind studies have also provided evidence for effectiveness of BoNT therapy in a number of painful disorders. These include cervical dystonia, pelvic pain, low back pain, plantar fasciitis, postsurgical painful spasms, myofascial pain syndromes, migraine, and chronic daily headaches. Long-term studies on cervical dystonia and low back pain have demonstrated safety and sustained efficacy after repeated injections. This Review focuses on the analgesic effects of BoNT and the mechanisms of its pain control as revealed by animal models, and provides evidence-based data on the efficacy of BoNT therapy in various pain syndromes in humans.