Efficacy and safety of repeated doses of botulinum toxin type B in type A resistant and responsive cervical dystonia

Eligibility criteria in clinical trials for cervical dystonia

INTRODUCTION

Cervical dystonia (CD) is the most common form of adult-onset focal dystonia. Because of a heterogeneous clinical presentation, the diagnosis rests on clinical opinion. During the last decades, several clinical trials have tested safety and efficacy of medical and surgical treatments for CD. We analyzed all the published CD trials and reviewed the strategies adopted for patient enrollment.

METHODS

The review included clinical trials in patients with CD published in PubMed. Studies were excluded if reviews, meta-analyses, post-hoc analyses on pooled data, or if not reporting a treatment for CD.

RESULTS

A total of 174 articles were identified; 134 studies met inclusion criteria. Diagnosis of CD varied among studies and in most cases was based on clinical judgement, using different descriptors such as "cervical dystonia" (37 studies), "idiopathic or isolated CD" (35), "primary CD" (13), and "torticollis" (40). Clinical judgement was supported by a phenomenological description of dystonia in four studies, and by a specific diagnostic strategy in other four. Finally, one study adopted general diagnostic criteria for dystonia. Inclusion and exclusion criteria proved heterogeneous across trials and were defined only in 108 studies, mainly considering age or the phenomenological pattern of muscle involvement.

CONCLUSION

The review showed lack of consolidated diagnostic criteria and non-uniformity of eligibility criteria for CD across clinical trials. There is need to move beyond clinical judgement as diagnostic criterion for selecting participants. New trials assessing specific CD patient subgroups or comparing medical and surgical procedures will need grounds that are more consistent.

Efficacy of botulinum toxin type B (rimabotulinumtoxinB) in patients with cervical dystonia previously treated with botulinum toxin type A: A post-marketing observational study in Japan

To date, efficacy data on botulinum toxin type B (rimabotulinumtoxinB) in patients with cervical dystonia (CD) previously treated with botulinum toxin type A in a large population are lacking; thus, we aimed to evaluate type B efficacy in this patient population. In a post-marketing observational cohort study, 150 patients previously treated with botulinum toxin type A were enrolled, of whom 138 were followed up for 1 year after the initial type B injection. Final observation data were available for 122 patients. Efficacy was evaluated using the Toronto Western Spasmodic Torticollis Rating Scale. Total score improved from 39.9 at baseline to 34.3 at 4 weeks after the first injection, and pain score improved from 8.9 to 7.9. Improvements were maintained through six further injections in two subpopulations: patients who showed resistance to botulinum toxin type A and patients who were not type A resistant but switched to type B. For a number of patients, even low doses (<5000 units) of botulinum toxin type B demonstrated efficacy. These findings support the efficacy of botulinum toxin type B in clinical settings for the management of CD symptoms, including pain, even at low doses, regardless of the patient's botulinum toxin type A resistance status.

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Botulinum toxin type B improved cervical dystonia symptoms and pain after 4 weeks.

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Botulinum toxin type B was effective even at low doses (<5000 units).

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The efficacy of toxin type B is not affected by toxin type A resistance status.

Immunogenicity of Botulinum Toxin Formulations: Potential Therapeutic Implications

Botulinum neurotoxins (BoNTs) are proteins produced by bacteria of the Clostridium family. Upon oral ingestion, BoNT causes the neuroparalytic syndrome botulism. There are seven serotypes of BoNT (serotypes A-G); BoNT-A and BoNT-B are the botulinum toxin serotypes utilized for therapeutic applications. Treatment with BoNT injections is used to manage chronic medical conditions across multiple indications. As with other biologic drugs, immunogenicity after long-term treatment with BoNT formulations may occur, and repeated use can elicit antibody formation leading to clinical nonresponsiveness. Thus, approaching BoNT treatment of chronic conditions with therapeutic formulations that minimize stimulating the host immune response while balancing patient responsiveness to therapy is ideal. Immunogenicity is a clinical limitation in many settings that use biologic drugs for treatment, and clinically relevant immunogenicity reduction has been achieved through engineering smaller protein constructs and reducing unnecessary formulation components. A similar approach has influenced the evolution of BoNT formulations. Three BoNT-A products and one BoNT-B product have been approved by the Food and Drug Administration (FDA) for therapeutic use: onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and rimabotulinumtoxinB; a fourth BoNT-A product, daxibotulinumtoxinA, is currently under regulatory review. Additionally, prabotulinumtoxinA is a BoNT-A product that has been approved for aesthetic indications but not therapeutic use. Here, we discuss the preclinical and clinical immunogenicity data that exist within the scientific literature and provide a perspective for considering immunogenicity as a key factor in choice of BoNT formulation.

New approaches to discovering drugs that treat dystonia

Introduction: Dystonia consists of involuntary movements, abnormal posturing, and pain. In adults, dystonia presents in a particular region of the body and causes significant disability due to pain as well as impairment in activities of daily living and employment. The current gold standard treatment, botulinum toxin (BoNT), has limitations - painful, frequent injections due to 'wearing off' of treatment effect; expense; and expected side effects like swallowing difficulty and weakness. There is a clear therapeutic gap in our current treatment options for dystonia and also a clear need for an effective novel treatment. Testing any novel treatment is complicated because most adults with focal dystonia are treated with BoNT. Areas covered: This review focuses on establishing the need for novel therapeutics. It also suggests potential leads from preclinical studies; and, discusses the issue of clinical trial readiness in the dystonia field. Expert opinion: Identifying a novel therapeutic intervention for dystonia patients faces two major challenges. The first is acknowledging the therapeutic gap that currently exists. Second, shifting some of our research aims in dystonia to clinical trial readiness is imperative if we are to be ready to test novel therapeutic agents.

Clinical differences between botulinum neurotoxin type A and B

In humans, the therapeutic use of botulinum neurotoxin A (BoNT/A) is well recognized and continuously expanding. Four BoNTs are widely available for clinical practice: three are serotype A and one is serotype B: onabotulinumtoxinA (A/Ona), abobotulinumtoxinA (A/Abo) and incobotulinumtoxinA (A/Inco), rimabotulinumtoxinB (B/Rima). A/Abo, A/Inco, A/Ona and B/Rima are all licensed worldwide for cervical dystonia. In addition, the three BoNT/A products are approved for blepharospasm and focal dystonias, spasticity, hemifacial spasm, hyperhidrosis and facial lines, with remarkable regional differences. These toxin brands differ for specific activity, packaging, constituents, excipient, and storage. Comparative literature assessing the relative safety and efficacy of different BoNT products is limited, most data come from reports on small samples, and only a few studies meet criteria of evidence-based medicine. One study compared the effects of BoNT/A and BoNT/B on muscle activity of healthy volunteers, showing similar neurophysiological effects with a dose ratio of 1:100. In cervical dystonia, when comparing the effects of BoNT/A and BoNT/B, results are more variable, some studies reporting roughly similar peak effect and overall duration (at a ratio of 1:66, others reporting substantially shorter duration of BoNT/B than BoNT/A (at a ratio 1/24). Although the results of clinical studies are difficult to compare for methodological differences (dose ratio, study design, outcome measures), it is widely accepted that: BoNT/B is clinically effective using appropriate doses as BoNT/A (1:40-50), injections are generally more painful, in most of the studies on muscular conditions, efficacy is shorter, and immunogenicity higher. Since the earliest clinical trials, it has been reported that autonomic side effects are more frequent after BoNT/B injections, and this observation encouraged the use of BoNT/B for sialorrhea, hyperhidrosis and other non-motor symptoms. In these indications the efficacy of toxins A and B are comparable and dose ratio is 1:25-30.

Botulinum Toxin in Pediatric Neurology: Switching Lanes From Death to Life

Botulinum neurotoxins are natural molecules produced by anaerobic spore-forming bacteria called Clostradium boltulinum. The toxin has a peculiar mechanism of action by preventing the release of acetylcholine from the presynaptic membrane. Consequently, it has been used in the treatment of various neurological conditions related to muscle hyperactivity and/or spasticity. Also, it has an impact on the autonomic nervous system by acting on smooth muscle, leading to its use in the management of pain syndromes. The use of botulinum toxin in children separate from adults has received very little attention in the literature. This review presents the current data on the use of botulinum neurotoxin to treat various neurological disorders in children.

Dystonia rating scales: critique and recommendations

Many rating scales have been applied to the evaluation of dystonia, but only few have been assessed for clinimetric properties. The Movement Disorders Society commissioned this task force to critique existing dystonia rating scales and place them in the clinical and clinimetric context. A systematic literature review was conducted to identify rating scales that have either been validated or used in dystonia. Thirty-six potential scales were identified. Eight were excluded because they did not meet review criteria, leaving 28 scales that were critiqued and rated by the task force. Seven scales were found to meet criteria to be "recommended": the Blepharospasm Disability Index is recommended for rating blepharospasm; the Cervical Dystonia Impact Scale and the Toronto Western Spasmodic Torticollis Rating Scale for rating cervical dystonia; the Craniocervical Dystonia Questionnaire for blepharospasm and cervical dystonia; the Voice Handicap Index (VHI) and the Vocal Performance Questionnaire (VPQ) for laryngeal dystonia; and the Fahn-Marsden Dystonia Rating Scale for rating generalized dystonia. Two "recommended" scales (VHI and VPQ) are generic scales validated on few patients with laryngeal dystonia, whereas the others are disease-specific scales. Twelve scales met criteria for "suggested" and 7 scales met criteria for "listed." All the scales are individually reviewed in the online information. The task force recommends 5 specific dystonia scales and suggests to further validate 2 recommended generic voice-disorder scales in dystonia. Existing scales for oromandibular, arm, and task-specific dystonia should be refined and fully assessed. Scales should be developed for body regions for which no scales are available, such as lower limbs and trunk.

Overview of botulinum toxin as a treatment for spasticity in stroke patients

Spasticity after the occurrence of stroke induces limb deformity, functional disability and/or pain in patients, which limits their activities of daily living and deteriorates their quality of life. Botulinum toxin (BTX) has recently been reported as an efficacious therapeutic agent for the treatment of spasticity. Systematic review and meta-analysis studies have demonstrated that BTX therapy after stroke reduces spasticity and increases physical activity capacity and performance levels. Moreover, BTX can be used as an adjuvant in physiotherapy. Several studies have confirmed that the combination of BTX therapy and physiotherapy improves motor recovery. However, to date, only a few such combination studies have been conducted and their findings are considered preliminary and controversial. Therefore, future studies are required to determine the appropriate combination of treatment methods that will aid motor recovery.

Torticollis

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

Immunogenicity of botulinum toxins

Botulinum neurotoxins are formulated biologic pharmaceuticals used therapeutically to treat a wide variety of chronic conditions, with varying governmental approvals by country. Some of these disorders include cervical dystonia, post-stroke spasticity, blepharospasm, migraine, and hyperhidrosis. Botulinum neurotoxins also have varying governmental approvals for cosmetic applications. As botulinum neurotoxin therapy is often continued over many years, some patients may develop detectable antibodies that may or may not affect their biological activity. Although botulinum neurotoxins are considered "lower risk" biologics since antibodies that may develop are not likely to cross react with endogenous proteins, it is possible that patients may lose their therapeutic response. Various factors impact the immunogenicity of botulinum neurotoxins, including product-related factors such as the manufacturing process, the antigenic protein load, and the presence of accessory proteins, as well as treatment-related factors such as the overall toxin dose, booster injections, and prior vaccination or exposure. Detection of antibodies by laboratory tests does not necessarily predict the clinical success or failure of treatment. Overall, botulinum neurotoxin type A products exhibit low clinically detectable levels of antibodies when compared with other approved biologic products. This review provides an overview of all current botulinum neurotoxin products available commercially, with respect to the development of neutralizing antibodies and clinical response.

Immunogenicity of botulinum toxins

Botulinum neurotoxins are formulated biologic pharmaceuticals used therapeutically to treat a wide variety of chronic conditions, with varying governmental approvals by country. Some of these disorders include cervical dystonia, post-stroke spasticity, blepharospasm, migraine, and hyperhidrosis. Botulinum neurotoxins also have varying governmental approvals for cosmetic applications. As botulinum neurotoxin therapy is often continued over many years, some patients may develop detectable antibodies that may or may not affect their biological activity. Although botulinum neurotoxins are considered "lower risk" biologics since antibodies that may develop are not likely to cross react with endogenous proteins, it is possible that patients may lose their therapeutic response. Various factors impact the immunogenicity of botulinum neurotoxins, including product-related factors such as the manufacturing process, the antigenic protein load, and the presence of accessory proteins, as well as treatment-related factors such as the overall toxin dose, booster injections, and prior vaccination or exposure. Detection of antibodies by laboratory tests does not necessarily predict the clinical success or failure of treatment. Overall, botulinum neurotoxin type A products exhibit low clinically detectable levels of antibodies when compared with other approved biologic products. This review provides an overview of all current botulinum neurotoxin products available commercially, with respect to the development of neutralizing antibodies and clinical response.

Clinical uses of botulinum neurotoxins: current indications, limitations and future developments

Botulinum neurotoxins (BoNTs) cause flaccid paralysis by interfering with vesicle fusion and neurotransmitter release in the neuronal cells. BoNTs are the most widely used therapeutic proteins. BoNT/A was approved by the U.S. FDA to treat strabismus, blepharospam, and hemificial spasm as early as 1989 and then for treatment of cervical dystonia, glabellar facial lines, axillary hyperhidrosis, chronic migraine and for cosmetic use. Due to its high efficacy, longevity of action and satisfactory safety profile, it has been used empirically in a variety of ophthalmological, gastrointestinal, urological, orthopedic, dermatological, secretory, and painful disorders. Currently available BoNT therapies are limited to neuronal indications with the requirement of periodic injections resulting in immune-resistance for some indications. Recent understanding of the structure-function relationship of BoNTs prompted the engineering of novel BoNTs to extend therapeutic interventions in non-neuronal systems and to overcome the immune-resistance issue. Much research still needs to be done to improve and extend the medical uses of BoNTs.

Immunogenicity of botulinum toxins

Botulinum neurotoxins are formulated biologic pharmaceuticals used therapeutically to treat a wide variety of chronic conditions, with varying governmental approvals by country. Some of these disorders include cervical dystonia, post-stroke spasticity, blepharospasm, migraine, and hyperhidrosis. Botulinum neurotoxins also have varying governmental approvals for cosmetic applications. As botulinum neurotoxin therapy is often continued over many years, some patients may develop detectable antibodies that may or may not affect their biological activity. Although botulinum neurotoxins are considered "lower risk" biologics since antibodies that may develop are not likely to cross react with endogenous proteins, it is possible that patients may lose their therapeutic response. Various factors impact the immunogenicity of botulinum neurotoxins, including product-related factors such as the manufacturing process, the antigenic protein load, and the presence of accessory proteins, as well as treatment-related factors such as the overall toxin dose, booster injections, and prior vaccination or exposure. Detection of antibodies by laboratory tests does not necessarily predict the clinical success or failure of treatment. Overall, botulinum neurotoxin type A products exhibit low clinically detectable levels of antibodies when compared with other approved biologic products. This review provides an overview of all current botulinum neurotoxin products available commercially, with respect to the development of neutralizing antibodies and clinical response.

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.

Rationale and design of a prospective study: Cervical Dystonia Patient Registry for Observation of OnaBotulinumtoxinA Efficacy (CD PROBE)

Background

A registry of patients with cervical dystonia (Cervical Dystonia Patient Registry for Observation of onaBotulinumtoxinA Efficacy [CD PROBE]) was initiated to capture data regarding physician practices and patient outcomes with onabotulinumtoxinA (BOTOX^®, Allergan, Inc., Irvine, CA, USA). Methods and baseline demographics from an interim analysis are provided.

Methods/Design

This is a prospective, multicenter, clinical registry in the United States enrolling subjects with cervical dystonia (CD) who are toxin naïve and/or new to the physicians' practices, or who had been in a clinical trial but received their last injection ≥ 16 weeks prior to enrollment. Subjects are followed over 3 injection cycles of onabotulinumtoxinA, with assessments at time of injection and 4-6 weeks later. Information on physician's practice, patient demographics, CD disease history, duration of treatment intervals and neurotoxin dose, dilution, use of electromyography, and muscles injected are collected. Outcomes are assessed by physicians and subjects using various questionnaires.

Discussion

This ongoing registry includes 609 subjects with the following baseline data: 75.9% female, 93.6% Caucasian, mean age 57.6 ± 14.3, age at symptom onset 48.3 ± 16.2, and time to diagnosis 5.4 ± 8.6 years, with an additional 1.0 ± 3.5 years before treatment. Of those employed at the time of diagnosis, 36.6% stopped working as a result of CD. CD PROBE, the largest clinical registry of CD treatment, will provide useful data on current treatment practices with onabotulinumtoxinA, potentially leading to refinements for optimization of outcomes.

Trial registration

NCT00836017

Therapeutic use of botulinum toxin in neurorehabilitation

The botulinum toxins (BTX), type A and type B by blocking vesicle acetylcholine release at neuro-muscular and neuro-secretory junctions can result efficacious therapeutic agents for the treatment of numerous disorders in patients requiring neuro-rehabilitative intervention. Its use for the reduction of focal spasticity following stroke, brain injury, and cerebral palsy is provided. Although the reduction of spasticity is widely demonstrated with BTX type A injection, its impact on the improvement of dexterity and functional outcome remains controversial. The use of BTX for the rehabilitation of children with obstetrical brachial plexus palsy and in treating sialorrhea which can complicate the course of some severe neurological diseases such as amyotrophic lateral sclerosis and Parkinson's disease is also addressed. Adverse events and neutralizing antibodies formation after repeated BTX injections can occur. Since impaired neurological persons can have complex disabling feature, BTX treatment should be viewed as adjunct measure to other rehabilitative strategies that are based on the individual's residual ability and competence and targeted to achieve the best functional recovery. BTX therapy has high cost and transient effect, but its benefits outweigh these disadvantages. Future studies must clarify if this agent alone or adjunctive to other rehabilitative procedures works best on functional outcome.

Obturator nerve block with botulinum toxin type B for patient with adductor thigh muscle spasm -a case report-

Obturator nerve block has been commonly used for pain management to prevent involuntary reflex of the adductor thigh muscles. One of several options for this block is chemical neurolysis. Neurolysis is done with chemical agents. Chemical agents used in the neurolysis of the obturator nerve have been alcohol, phenol, and botulinum toxin. In the current case, a patient with spasticity of the adductor thigh muscle due to cervical cord injury had obturator nerve neurolysis done with botulinum toxin type B (BoNT-B). Most of the previous studies have used BoNT-A with only a few reports that have used BoNT-B. BoNT-B has several advantages and disadvantages over BoNT-A. Thus, we report herein a patient who successfully received obturator nerve neurolysis using BoNT-B to treat adductor thigh muscle spasm.

An open-label, sequential dose-escalation, safety, and tolerability study of rimabotulinumtoxinb in subjects with cervical dystonia

OBJECTIVES

Evaluate the safety and efficacy of a sequential dose escalation of rimabotulinumtoxinB (BoNT-B) in cervical dystonia (CD) subjects.

METHODS

This multicenter, open-label, within-subject, sequential dose-escalation study (BoNT-B dosed at 10,000, 12,500, and 15,000 Units) evaluated subjects over each phase of treatment at preinjection and at periodic intervals postinjection. Adverse events, vital signs, and laboratory results were recorded. Efficacy measures included the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and three visual analog scales (VASs).

RESULTS

119 out of 145 CD subjects received all three doses in sequence. Dry mouth and dysphagia were the most common adverse events, and both decreased in frequency by the final injection, despite the increasing doses of the escalation. TWSTRS-Total and subscale scores demonstrated significant improvements following all doses at the week 2, 4, 8, and 12 assessments, with the exception of disability and pain at week 12 with the lowest dose. All VAS scores demonstrated similar improvements following all doses. The mean number of weeks in each phase of the study was 12.1 weeks (10,000 Units), 12.9 weeks (12,500 Units), and 13.9 weeks (15,000 Units).

CONCLUSION

BoNT-B was well tolerated and efficacious at 10,000, 12,500, and 15,000 Units in this within-subject, sequential dose-escalation study in CD subjects.

Application of botulinum toxin in pain management

Botulinum toxin has been used for the treatment of many clinical disorders by producing temporary skeletal muscle relaxation. In pain management, botulinum toxin has demonstrated an analgesic effect by reducing muscular hyperactivity, but recent studies suggest this neurotoxin could have direct analgesic mechanisms different from its neuromuscular actions. At the moment, botulinum toxin is widely investigated and used in many painful diseases such as myofascial syndrome, headaches, arthritis, and neuropathic pain. Further studies are needed to understand the exact analgesic mechanisms, efficacy and complications of botulinum toxin in chronic pain disorders.

NeuroBloc/Myobloc: unique features and findings

This review outlines factors that differentiate botulinum toxin serotypes and focuses on the unique features of the commercially available form of BoNT-B (i.e., Myobloc/NeuroBloc). A series of preclinical studies in Cynomolgus monkeys are reviewed. Each of these studies used electrophysiologic measures of changes in the compound muscle action potential (CMAP) following supramaximal nerve stimulation to evaluate the direct effects of the toxin in the injected muscle, as well as the spread of the effects to non-injected muscles. The results of 14 studies were summarized, including several that compared the effects of equivalent doses of BoNT-A and BoNT-B injected into muscles on the opposite side of the same monkey. There is clear evidence that when equivalent doses of BoNT-A and BoNT-B are assessed, there is greater spread to both nearby and remote non-injected muscles associated with BoNT-A. Similar studies in the mouse model demonstrated that high, but non-lethal, doses of BoNT-A unilaterally injected into the foot resulted in spread of the effects across the midline to the opposite non-treated foot, while there was no evidence of bilateral effects with equivalent unilateral injections of BoNT-B. Finally, this review summarizes a series of studies in the trapezius and gastrocnemius muscles of monkeys demonstrating that when doses producing equivalent initial effects of BoNT-A and BoNT-B are compared, the duration of effects and the time course of recovery are almost identical across toxins.

Botulinum toxin type B vs. type A in toxin-naïve patients with cervical dystonia: Randomized, double-blind, noninferiority trial

The objective of this study was to compare efficacy, safety, and duration of botulinum toxin type A (BoNT-A) and type B (BoNT-B) in toxin-naïve cervical dystonia (CD) subjects. BoNT-naïve CD subjects were randomized to BoNT-A or BoNT-B and evaluated in a double-blind trial at baseline and every 4-weeks following one treatment. The primary measure was the change in Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) from baseline to week 4 post-injection. Secondary measures included change in TWSTRS-subscale scores, pain, global impressions, and duration of response and safety assessments. The study was designed as a noninferiority trial of BoNT-B to BoNT-A. 111 subjects were randomized (55 BoNT-A; 56 BoNT-B). Improvement in TWSTRS-total scores 4 weeks after BoNT-B was noninferior to BoNT-A (adjusted means 11.0 (SE 1.2) and 8.8 (SE 1.2), respectively; per-protocol-population (PPP)). The median duration of effect of BoNT-A and BoNT-B was not different (13.1 vs. 13.7 weeks, respectively; P-value = 0.833; PPP). There were no significant differences in the occurrence of injection site pain and dysphagia. Mild dry mouth was more frequent with BoNT-B but there were no differences for moderate/severe dry mouth. In this study, both BoNT-A and B were shown to be effective and safe for the treatment of toxin-naive CD subjects.

Selective denervation of the levator scapulae muscle: an amendment to the Bertrand procedure for the treatment of spasmodic torticollis

Object

The purpose of this cadaveric study was to explore a modification to the Bertrand procedure for the treatment of spasmodic torticollis, namely the denervation of the levator scapulae (LS) muscle for laterocollis.

Methods

The authors performed a series of 9 cadaveric dissections. Five were done to identify the anterior innervation of the LS, and the remaining 4 were to identify the tendinous insertions of the LS onto the lateral masses of the cervical spine via a posterior approach. The nerve supply to the LS from the anterior divisions of the C-3 and C-4 nerve roots and the contribution from the dorsal scapular nerve were identified over the anterior surface of the muscle.

Results

The C-3 and C-4 nerve root branches were situated within 2 cm of each other and inferior to the punctum nervosum. The dorsal scapular contribution was clearly identified in 2 cadavers. Selective denervation of this muscle is possible through the same posterior triangle incision used for denervating the sternocleidomastoid muscle of its accessory nerve branches. This approach will be helpful in patients with laterocollis contralateral to the direction of chin turning. The authors compare this approach to the posterior approach for sectioning the insertions of the LS muscle onto the C1–4 posterior tubercles. The latter approach is appropriate for ipsilateral laterocollis.

Conclusions

The posterior triangle approach for denervating the LS muscle is a safe and easy addition to the Bertrand procedure and can be helpful in selected cases of torticollis with a laterocollis component.

Cervical Dystonia

Cervical dystonia, which is the most common form of focal dystonia, presents with sustained neck spasms, abnormal head posture, head tremor, and pain. One of the interesting and unique features of cervical dystonia is the geste antagoniste. There is not a well-described pathophysiology for cervical dystonia, but several hypotheses report involvement at the central and peripheral level. Treatment options include: oral medical therapy, botulinum toxin injection, and surgery. Oral medical therapy has limited efficacy in control of the symptoms of cervical dystonia. Two types of botulinum toxin, types A and B, are being used for treatment of cervical dystonia, with equivalent benefit. Surgery is an option when other treatments fail or become ineffective. The surgical procedures are brain lesioning, brain stimulation, and peripheral surgical intervention. Several trials are currently ongoing in the United States and Europe to evaluate the efficacy of deep brain surgery in cervical dystonia.

Cervical dystonia: disease profile and clinical management

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

Comparison of botulinum neurotoxin preparations for the treatment of cervical dystonia

BACKGROUND

Comparative studies of botulinum neurotoxin preparations to date have generally examined 2 preparations at prespecified dose ratios in relatively homogeneous groups of patients under controlled study conditions. It is unclear whether the differences in adverse-event rates that have been noted under these controlled conditions can be generalized to the broader population of cervical dystonia patients, who are treated with a wider range of doses in a variety of settings.

OBJECTIVE

We conducted a systematic review and analysis of the published literature to compare rates of dysphagia and dry mouth in studies of botulinum neurotoxin products.

METHODS

We searched the MEDLINE, EMBASE, Biosis, SciSearch, JICST (Japan Science and Technology Center), and Pascal databases from 1985 through 2006 using the terms cervical dystonia, spasmodic torticollis, and botulinum toxin for original English-language studies of Botox, Dysport, or Myobloc in the treatment of cervical dystonia (or spasmodic torticollis) that documented adverse events by treatment or patient. Studies that involved patients with various types of dystonias or movement disorders were included as long as adverse events were reported separately for those with cervical dystonia. Rates of dysphagia with the original preparation of Botox were considered separately from those with the current preparation of Botox.

RESULTS

Seventy published articles were included in the analysis (30 Botox, 24 Dysport, 3 Botox + Dysport, 11 Myobloc, 2 Botox + Myobloc). Mean total doses per treatment ranged from 60 to 374 U for Botox, 125 to 1200 U for Dysport, and 579 to 19,853 U for Myobloc. Botox was associated with a significantly lower rate of dysphagia than Dysport, with mean dysphagia rates of 10.5% for original Botox, 8.9% for current Botox, and 26.8% for Dysport (both, P < 0.05). Myobloc was associated with dry mouth (3.2%-90.0%) in 9 of 13 studies, but this adverse event was not reported in a sufficient number of studies of botulinum toxin type A preparations (Botox, n = 2; Dysport, n = 6) to permit statistical comparison. In the weighted analysis, the duration of effect differed between botulinum neurotoxin products (current Botox > Myobloc > original Botox > Dysport; all, P < 0.001), but only 43 (61.4%) of the 70 studies reported duration, and the definitions varied.

CONCLUSION

The results of this analysis indicate differences in adverse-event rates between botulinum neurotoxin preparations, suggesting that use of these products should be based on their individual dosing, efficacy, and safety profiles.

Botulinum toxin in poststroke spasticity

Poststroke hemiparesis, together with abnormal muscle tone, is a major cause of morbidity and disability. Although most hemiparetic patients are able to reach different ambulatory levels with rehabilitation efforts, upper and lower limb spasticity can impede activities of daily living, personal hygiene, ambulation and, in some cases, functional improvement. The goals of spasticity management include increasing mobility and range of motion, attaining better hygiene, improving splint wear and other functional activities. Conservative measures, such as positioning, stretching and exercise are essential in spasticity management, but alone often are inadequate to effectively control it. Oral antispastic medications often provide limited effects with short duration and frequent unwanted systemic side effects, such as weakness, sedation and dry mouth. Therefore, neuromuscular blockade by local injections have become the first choice for the treatment of focal spasticity, particularly in stroke patients. Botulinum toxin (BTX), being one of the most potent biological toxins, acts by blocking neuromuscular transmission via inhibiting acetylcholine release. Currently, focal spasticity is being treated successfully with BTX via injecting in the spastic muscles. Two antigenically distinct serotypes of BTX are available on the market as type A and B. Clinical studies of BTX used for spastic hemiplegic patients are reviewed in this article in two major categories, upper and lower limb applications. This review addresses efficacy in terms of outcome measures, such as muscle tone reduction and functional outcome, as well as safety issues. Application modifications of dose, dilutions, site of injections and combination therapies with BTX injections are also discussed.

Botulinum toxin in the management of dystonia

Dystonia is a neurologic disorder that can occur at any age and often results in significant disability. The therapeutic application of botulinum toxin has revolutionized the treatment of this disorder, particularly for the adult-onset focal forms such as cervical dystonia and blepharospasm. The two available commercial preparations, botulinum toxin types A and B, have been shown to be equally efficacious in cervical dystonia and are both reasonable first-line choices for treating other forms of focal dystonia. Preliminary studies have suggested that differences in tolerability and immunogenicity may exist between the two preparations, but this has not been adequately evaluated. Because of high cost, complicated administration, potentially serious side effects, and the risk of developing immunoresistance, this treatment should be administered only by a physician with sufficient background in the diagnosis and treatment of dystonia, to ensure optimal outcomes.

Botulinum toxin type B improves the speed of reaching in children with cerebral palsy and arm dystonia: an open-label, dose-escalation pilot study

Seven children between 2 and 15 years of age with cerebral palsy and upper extremity dystonia were enrolled in an open-label, dose-escalation pilot clinical trial of botulinum toxin type B (Myobloc), injected into the biceps and brachioradialis muscles of I or both arms. The primary outcome measure was the change in maximum speed of hand movement during attempted forward reaching. Escalating doses of 12.5, 25, and 50 U/kg per muscle were injected at each of 3 visits. Reaching speed improved in response to injection, and dystonia scores on the Burke-Fahn-Marsden dystonia scale, the Unified Dystonia Rating Scale, and the Unified Parkinson's Disease Rating Scale improved. There was not a dose-related effect on efficacy. There were no serious adverse events. Two children reported transient weakness. These results support the use of botulinum toxin type B as a safe and effective treatment for upper extremity dystonia in children with cerebral palsy. Larger controlled trials are needed to confirm these results.

Botulinum toxin therapy for cervical dystonia

Cervical dystonia (CD) is the most common form of focal dystonia treated with botulinum toxin (BoNT) injections. BoNT has been shown in numerous clinical trials to correct the abnormal posture and movement and to markedly reduce pain associated with CD. In addition, BoNT has favorably modified the natural history of the disease by preventing contractures and other complications of CD, such as secondary degenerative changes of the cervical spine and associated radiculopathy. In a long-term follow-up of patients treated for up to 20 years, the duration of response appears to be sustained and the risk of immunoresistance due to blocking antibodies is relatively small. This review provides and update on the treatment of CD with BoNT type A (BOTOX, Dysport, Xeomin and BoNT type B (Myobloc, NeuroBloc.

An update on the first decade of the European centralized procedure: how many innovative drugs?

AIMS

In a previous paper, we proposed an algorithm to assess the degree of therapeutic innovation of the agents approved by the European centralized procedure, which must be followed by biotechnological products and is optional for drugs claimed as innovative. A low overall degree of therapeutic innovation (about 30%) was found. This figure may be an underestimate of the actual level of innovation, because common biotechnological products, such as recombinant human insulins, must follow this procedure. To test the hypothesis that therapeutic innovation prevails among nonbiotechnological products, we evaluated separately the degree of therapeutic innovation of biotechnological vs. nonbiotechnological agents in the first decade of European Medicines Agency activity, also studying a possible time trend.

METHODS

We assessed, for each drug: (i) the seriousness of the target disease, (ii) the availability of previous treatments, and (iii) the extent of therapeutic effect according to the previously proposed algorithm.

RESULTS

Our analysis considered 251 medicinal products corresponding to 198 active substances, classified according to four main areas as therapeutic agents (88.9%), diagnostics (5.5%), vaccines (5.1%) and life-style drugs (0.5%). Among all therapeutic agents, 49 out of 176 agents (28%) were classified as having an important degree of therapeutic innovation. Fifteen out of 60 biotechnological therapeutic agents were considered important therapeutic innovations (25%), whereas this figure was 29% for nonbiotechnological agents.

CONCLUSIONS

Among active substances claimed as innovative by the manufacturers, only a minority deserve this definition according to our algorithm.