Evolution of dose and response to botulinum toxin A in cervical dystonia: a multicenter study

Botulinum Toxin in Movement Disorders: An Update

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

The therapeutic usage of botulinum toxin (Botox) in non-cosmetic head and neck conditions - An evidence based review

Botulinum toxin (Botox) is an exotoxin produced from Clostridium botulinum. It blocks the release of acetylcholine from the cholinergic nerve end plates resulting in inactivity of the muscles or glands innervated. The efficacy of Botox in facial aesthetics is well established; however, recent literature has highlighted its utilization in multiple non-cosmetic medical and surgical conditions. The present article reviews the current evidence pertaining to Botox use in the non-cosmetic head and neck conditions. A literature search was conducted using MEDLINE, EMBASE, ISI Web of Science and the Cochrane databases limited to English Language articles published from January 1980 to December 2014. The findings showed that there is level 1 evidence supporting the efficacy of Botox in the treatment of laryngeal dystonia, headache, cervical dystonia, masticatory myalgia, sialorrhoea, temporomandibular joint disorders, bruxism, blepharospasm, hemifacial spasm and rhinitis. For chronic neck pain there is level 1 evidence to show that Botox is ineffective. Level 2 evidence exists for vocal tics and trigeminal. For stuttering, facial nerve paresis, Frey's syndrome and oromandibular dystonia the evidence is level 4. Thus, there is compelling evidence in the published literature to demonstrate the beneficial role of Botox in a wide range of non-cosmetic conditions pertaining to the head and neck (mainly level 1 evidence). With more and more research, the range of clinical applications and number of individuals getting Botox will doubtlessly increase. Botox appears to justify its title as 'the poison that heals'.

Botulinum toxin treatment failures in cervical dystonia: causes, management, and outcomes

Botulinum toxin (BoNT) is highly effective in the treatment of cervical dystonia (CD), yet a significant proportion of patients report low levels of satisfaction following treatment and fail to follow up for repeated treatments. The goal of this study was to determine the reasons that some patients have unsatisfactory responses. A total of 35 subjects who came to our center requesting alternative treatments due to unsatisfactory responses following BoNT treatment for CD were evaluated. Included were 26 women and 9 men with an average age of 57.1 years (range 25-82 years), and an average duration of illness of 12.5 years (range 1-55 years). Details of unsatisfactory BoNT treatments were methodically collected by a movement specialist using a standardized intake form, including provider subspecialty, product used, the number of satisfactory or unsatisfactory trials, doses given, specific muscles treated, the use of electromyographic guidance, side effects, and tests of resistance. The specialist then provided repeat treatments if indicated, and followed each case until the reasons for unsatisfactory outcomes could be determined. Multiple reasons for unsatisfactory outcomes were found. They included suboptimal BoNT doses, suboptimal muscle targeting, intolerable side effects, complex movement patterns, discordant perceptions, and incorrect diagnoses. Only one patient was functionally resistant to BoNT. Of 32 subjects who received repeat BoNT treatments, 25 (78 %) achieved satisfactory responses after revision of the original treatment plan. These results indicate that the majority of unsatisfactory responses to BoNT treatment of CD were caused by correctible factors and imply a need for improved education regarding optimal treatment methods.

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

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

Selective peripheral denervation for cervical dystonia: long-term follow-up

OBJECTIVE

61 procedures with selective peripheral denervation for cervical dystonia were retrospectively analysed concerning surgical results, pain, quality of life (QoL) and recurrences.

METHODS

The patients were assessed with the Tsui torticollis scale, Visual Analogue Scale (VAS) for pain and Fugl-Meyer scale for QoL. Evaluations were performed preoperatively, early postoperatively, at 6 months, then at a mean of 42 (13-165) months. All patients underwent electromyogram at baseline, which was repeated in cases who presented with recurrence of symptoms after surgery.

RESULTS

Six months of follow-up was available for 55 (90%) of the procedures and late follow-up for 34 (56%). The mean score of the Tsui scale was 10 preoperatively. It improved to 4.5 (p<0.001) at 6 months, and 5.3 (p<0.001) at late follow-up. VAS for pain improved from 6.5 preoperatively to 4.2 (p<0.001) at 6 months and 4 (p<0.01) at late follow-up. The Fugl-Meyer score for QoL improved from 43.3 to 46.6 (p<0.05) at 6 months, and to 51.1 (p<0.05) at late follow-up. Major reinnervation and/or change in the dystonic pattern occurred following 29% of the procedures, and led in 26% of patients to reoperation with either additional denervation or pallidal stimulation.

CONCLUSIONS

Selective peripheral denervation remains a surgical option in the treatment of cervical dystonia when conservative measures fail. Although the majority of patients experience a significant relief of symptoms, there is a substantial risk of reinnervation and/or change in the pattern of the cervical dystonia.

The focal dystonias: current views and challenges for future research

The most common forms of dystonia are those that develop in adults and affect a relatively isolated region of the body. Although these adult-onset focal dystonias are most prevalent, knowledge of their etiologies and pathogenesis has lagged behind some of the rarer generalized dystonias, in which the identification of genetic defects has facilitated both basic and clinical research. This summary provides a brief review of the clinical manifestations of the adult-onset focal dystonias, focusing attention on less well understood clinical manifestations that need further study. It also provides a simple conceptual model for the similarities and differences among the different adult-onset focal dystonias as a rationale for lumping them together as a class of disorders while at the same time splitting them into subtypes. The concluding section outlines some of the most important research questions for the future. Answers to these questions are critical for advancing our understanding of this group of disorders and for developing novel therapeutics.

[Applications of botulinum toxin in Neurology]

At present, botulinum toxin (BT) is one of the most fundamental available drugs in Neurology, only comparable with levodopa. BT is currently used in those entities characterized by excessive muscle contraction, including dystonia and spasticity. In addition, BT has been used to control pain associated with increased muscle contraction in dystonia and spasticity, but also is useful to control chronic pain not associated with muscle contraction, such as chronic daily headache. Finally, BT is useful in sialorrhoea and bruxism. The mechanism of action is complex, mainly acting on terminal neuromuscular junction, but also exhibiting analgesic properties, probably through inhibition of pain neurotransmitters release.

An evidence-based review of botulinum toxin (Botox) applications in non-cosmetic head and neck conditions

Botulinum toxin (Botox) is an exotoxin produced from Clostridium botulinum. It works by blocking the release of acetylcholine from the cholinergic nerve end plates leading to inactivity of the muscles or glands innervated. Botox is best known for its beneficial role in facial aesthetics but recent literature has highlighted its usage in multiple non-cosmetic medical and surgical conditions. This article reviews the current evidence pertaining to Botox use in the head and neck. A literature review was conducted using The Cochrane Controlled Trials Register, Medline and EMBASE databases limited to English Language articles published from 1980 to 2012. The findings suggest that there is level 1 evidence supporting the efficacy of Botox in the treatment of spasmodic dysphonia, essential voice tremor, headache, cervical dystonia, masticatory myalgia, sialorrhoea, temporomandibular joint disorders, bruxism, blepharospasm, hemifacial spasm and rhinitis. For chronic neck pain there is level 1 evidence to show that Botox is ineffective. Level 2 evidence exists for vocal tics, trigeminal neuralgia, dysphagia and post-laryngectomy oesophageal speech. For stuttering, 'first bite syndrome', facial nerve paresis, Frey's syndrome, oromandibular dystonia and palatal/stapedial myoclonus the evidence is level 4. Thus, the literature highlights a therapeutic role for Botox in a wide range of non-cosmetic conditions pertaining to the head and neck (mainly level 1 evidence). With ongoing research, the spectrum of clinical applications and number of people receiving Botox will no doubt increase. Botox appears to justify its title as 'the poison that heals'.

Use of injectable spasticity management agents in a cancer center

PURPOSE

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

METHODS

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

RESULTS

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

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.