Comparison of botulinum toxin serotypes A and B for the treatment of cervical dystonia

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 Neurotoxin Type A Free of Complexing Proteins (XEOMIN??) in Focal Dystonia

Botulinum neurotoxin type A (BTX-A) weakens voluntary muscle strength and is an effective therapy for focal dystonia, including cervical dystonia (CD) and benign essential blepharospasm (BEB). It is also known to relieve hemifacial spasm and focal spasticity in children and adults. In addition, BTX-A has been shown to be effective in a wide range of other indications, such as gastrointestinal disorders, hyperhidrosis and cosmetic wrinkle correction (e.g. glabellar frown lines). A new formulation of BTX-A, NT 201 (XEOMIN((R))) has been developed. NT 201 is a formulation of pure BTX-A free of complexing proteins and, therefore, may have a reduced immunogenic potential compared with other BTX-A preparations. The pre-clinical and clinical development of NT 201 is reviewed in this article.A total of five clinical trials were completed in Europe and Israel. Two studies were conducted in 46 healthy volunteers. A further three studies in 816 patients were conducted to provide data on the safety and efficacy of NT 201 in the treatment of CD and BEB. NT 201 was found to provide non-inferior efficacy and safety profiles in the treatment of CD and BEB compared with a BTX-A preparation containing complexing proteins (BOT [BOTOX((R))]). The clinical development programme of NT 201 showed a 1 : 1 NT 201 to BOT dose ratio. The pre-clinical studies conducted with NT 201 showed an acceptable safety profile and support the use of NT 201 in an intramuscular administration regimen for patients with CD and BEB. NT 201 was effective, well tolerated and non-inferior to BOT in the treatment of both CD and BEB. In addition, there were no differences between the two therapies in terms of onset of action, duration and waning of effect. Further research is required to determine the long-term efficacy and safety profile of NT 201.

Treatment of dystonia

Dystonia, defined as a neurological syndrome characterised by involuntary, patterned, sustained, or repetitive muscle contractions of opposing muscles, causing twisting movements and abnormal postures, is one of the most disabling movement disorders. Although gene mutations and other causes are increasingly recognised, most patients have primary dystonia without a specific cause. Although pathogenesis-targeted treatment is still elusive, the currently available symptomatic treatment strategies are quite effective for some types of dystonia in relieving involuntary movements, correcting abnormal posture, preventing contractures, reducing pain, and improving function and quality of life. A small portion of patients have a known cause and respond to specific treatments, such as levodopa in dopa-responsive dystonia or drugs that prevent copper accumulation in Wilson's disease. Therapeutic options must be tailored to the needs of individual patients and include chemodenervation with botulinum toxin injections for patients with focal or segmental dystonia, and medical treatments or deep brain stimulation for patients with generalised dystonia.

Botulinum toxin: Clinical use

Since its development for the use of blepharospasm and strabismus more than 2.5 decades ago, botulinum neurotoxin (BoNT) has become a versatile drug in various fields of medicine. It is the standard of care in different disorders such as cervical dystonia, hemifacial spasm, focal spasticity, hyperhidrosis, ophthalmological and otolaryngeal disorders. It has also found widespread use in cosmetic applications. Many other indications are currently under investigation, including gastroenterologic and urologic indications, analgesic management and migraine. This paper is an extensive review of the spectrum of BoNT clinical applications.

Clinical use of non-A botulinum toxins: botulinum toxin type B

Botulinum neurotoxin type B (BT, BT-B) has been used as NeuroBloc/MyoBloc since 1999 for treatment of cervical dystonia, hyperhidrosis, spastic conditions, cerebral palsy, hemifacial spasm, bladder dysfunction, spasmodic dysphonia, sialorrhoea, anal fissures, piriformis syndrome, various pain conditions and cosmetic applications. Generally, its therapeutic effects are comparable to BT type A (BT-A). The adverse effect profiles of BT-B and BT-A, however, differ considerably. BT-B has been found to produce more regional as well as systemic anticholinergic adverse effects, such as dryness of mouth, accommodation difficulties, conjunctival irritation, reduced sweating, dysphagia, heartburn, constipation, bladder voiding difficulties and dryness of nasal mucosa. In BT-B the relationship between autonomic and motor effects known from BT-A is substantially shifted towards autonomic effects. BT-B, therefore, should be used carefully in patients with autonomic disorders and in patients with concomitant anticholinergic therapy. If NeuroBloc/MyoBloc is used to treat cervical dystonia patients with antibody-induced failure of BT-A therapy, 86% of those will develop complete secondary therapy failure after five applications. If NeuroBloc/MyoBloc used to treat cervical dystonia patients without prior exposure to BT, 44% of those will develop complete secondary therapy failure after nine applications. NeuroBloc/MyoBloc, therefore, is associated with substantial antigenicity problems originating from a particular low specific biological potency. Systemic anticholinergic adverse effects and high antigenicity limits the clinical use of NeuroBloc/MyoBloc considerably.

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.

Treatment of dystonia

Dystonia may be a sign or symptom, that is comprised of complex abnormal and dynamic movements of different etiologies. A specific cause is identified in approximately 28% of patients, which only occasionally results in specific treatment. In most cases, treatment is symptomatic and designed to relieve involuntary movements, improve posture and function and reduce associated pain. Therapeutic options are dictated by clinical assessment of the topography of dystonia, severity of abnormal movements, functional impairment and progression of disease and consists of pharmacological, surgical and supportive approaches. Several advances have been made in treatment with newer medications, availability of different forms of botulinum toxin and globus pallidus deep brain stimulation (DBS). For patients with childhood-onset dystonia, the majority of whom later develop generalized dystonia, oral medication is the mainstay of therapy. Recently, DBS has emerged as an effective alternative therapy. Botulinum toxin is usually the treatment of choice for those with adult-onset primary dystonia in which dystonia usually remains focal. In patients with secondary dystonia, treatment is challenging and efficacy is typically incomplete and partially limited by side effects. Despite these treatment options, many patients with dystonia experience only partial benefit and continue to suffer significant disability. Therefore, more research is needed to better understand the underlying cause and pathophysiology of dystonia and to explore newer medications and surgical techniques for its treatment.

Treatment of headaches with botulinum toxin

Primary headache disorders, such as migraine, chronic daily headache (CDH), and chronic tension-type headache (CTTH), are some of the most frequent disorders encountered by physicians in the outpatient setting. Chronic headache disorders cause significant morbidity and functional impairment. Despite important advances in both pharmacological and behavioral management of headache disorders, a number of patients remain treatment resistant. Botulinum toxin (BT) is emerging as a new therapeutic alternative in the preventative treatment of headaches. BT has several advantages over current prophylactic strategies, such as reduced side-effect profile and improved patient compliance. Furthermore, there have been several studies supporting the safety and tolerability of BT in the treatment of headache disorders. Although additional large-scale studies are needed to clarify clinical predictors of response as well as optimal dosing, injection sites and mechanism of action, BT has demonstrated efficacy in the treatment of migraines and CDH. The evidence for the treatment for CTTH is less compelling.