The botulinum toxins in the treatment of cervical dystonia

The use of botulinum toxin to treat cervical dystonia (CD) has dramatically improved the quality of life of patients with this disabling, often painful disease. Two forms of toxins, botulinum toxin type A (BTX-A) and botulinum toxin type B (BTX-B), have each been studied in large multicenter trials in subjects with CD. A study of BTX-A demonstrated improvement of 5.15 to 10.65 degrees in head position using the Cervical Dystonia Severity Scale (CDSS) in those treated with BTX-A (trade name BOTOX) compared with placebo. A study in patients who continued to respond to BTX-A and a similarly designed study in patients who were resistant to BTX-A demonstrated statistical improvement in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) in those treated with BTX-B (evaluated as NeuroBloc) compared with placebo. The potential availability of both forms of toxin will allow physicians to offer further treatment options to patients with CD.     

Visual system side effects caused by parasympathetic dysfunction after botulinum toxin type B injections.

Botulinum toxin type B (BTX-B) has been approved by the Food and Drug Administration for the treatment of cervical dystonia. However, as with botulinum toxin type A (BTX-A) it has off-label uses, such as for hyperhidrosis, focal dystonias, spasticity, and facial wrinkles. BTX-B has also been shown to be a safe and effective alternative for patients who are resistant to BTX-A. The most commonly reported side effects include dry mouth and dysphagia. To date, there have been few reports of visual disturbances associated with BTX-B use. In this study, we report on three individual patients who received BTX-B and who subsequently developed parasympathetic dysfunction of the visual system after injections of BTX-B at remote sites.     

Autonomic function after botulinum toxin type A or B: a double-blind, randomized trial

To compare autonomic effects of botulinum toxin (BTX), we randomized patients with cervical dystonia to receive either BTX-A or BTX-B in a double-blind manner. Efficacy and physiologic questionnaire measures of autonomic function were assessed at baseline and 2 weeks after injection. Patients treated with BTX-B had less saliva production (p < 0.01) and greater severity of constipation (p = 0.037) than those treated with BTX-A, but did not differ in other tests of autonomic functions.     

Clinico-immunologic aspects of botulinum toxin type B treatment of cervical dystonia

In this multicenter study of 100 patients with cervical dystonia, we examined the immunogenicity of botulinum toxin type B (BTX-B) and correlated the clinical response with the presence of blocking antibodies (Abs) using a novel mouse protection assay. One-third of the patients who were negative for BTX-B Abs at baseline became positive for BTX-B Abs at last visit. Thus, the high antigenicity of BTX-B limits its long-term efficacy.     

A randomized,double-masked,crossover comparison of the efficacy and safety of botulinum toxin type A produced from the original bulk toxin source and current bulk toxin source for the treatment of cervical dystonia

In 1997, the US FDA approved a new bulk toxin source (now referred to as current) for the manufacture of botulinum toxin type A (BTX-A). The current BTX-A preparation has a lower neurotoxin complex protein load than the original BTX-A preparation, which may reduce antigenic potential. The present double-masked, multicenter study compared the efficacy and safety of BTX-A (BOTOX) produced from both original and current bulk toxin sources for the treatment of cervical dystonia. Patients (N = 133) were injected with BTX-A produced from original and current bulk toxin sources using a crossover design. Adverse events were assessed at each visit. Efficacy was assessed at 2 and 6 weeks post-injection using the severity and pain-disability subscales of the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Mean BTX-A doses were comparable (original: 155 U, current: 156 U). Both BTX-A preparations produced similar, statistically significant reductions in TWSTRS severity and pain-disability scores at weeks 2 and 6 post-injection. The original and current BTX-A preparations showed no significant differences in adverse events, including both treatment-related (34%, 31%) and treatment-unrelated (27%, 32%), respectively. BTX-A produced from the original and current bulk toxin sources showed comparable efficacy and safety in the treatment of cervical dystonia; both significantly reduced dystonia severity and pain.     

Expanding use of botulinum toxin

Botulinum toxin type A (BTX-A) is best known to neurologists as a treatment for neuromuscular conditions such as dystonias and spasticity and has recently been publicized for the management of facial wrinkles. The property that makes botulinum toxin type A useful for these various conditions is the inhibition of acetylcholine release at the neuromuscular junction. Although botulinum toxin types A and B (BTX-A and BTX-B) continue to find new uses in neuromuscular conditions involving the somatic nervous system, it has also been recognized that the effects of these medications are not confined to cholinergic neurons at the neuromuscular junction. Acceptors for BTX-A and BTX-B are also found on autonomic nerve terminals, where they inhibit acetylcholine release at glands and smooth muscle. This observation led to trials of botulinum neurotoxins in various conditions involving autonomic innervation. The article reviews the emerging use of botulinum neurotoxins in these and selected other conditions, including sialorrhea, primary focal hyperhidrosis, pathological pain and primary headache disorders that may be of interest to neurologists and related specialists.     

Secondary non-response due to antibody formation in a child after three injections of botulinum toxin B into the salivary glands

Botulinum toxin (BTX) offers a new treatment option to reduce drooling in adults and children. Antibody formation against BTX is known to be one reason for clinical secondary non-response to this treatment. This is a case report on the development of secondary non-response to BTX type B (BTX-B) in a 15-year-old male, with bilateral dyskinetic cerebral palsy (Gross Motor Function Classification System Level IV) with additional learning disability* and microcephaly, treated for the indication of drooling. After three successful treatment sessions, the fourth and fifth injections showed no clinical response. This was associated with the presence of antibodies against BTX-B as determined using the mouse diaphragm assay. Thus, formation of neutralizing antibodies against BTX-B appears to be an important issue, not only in patients treated for cervical dystonia but also in children treated for drooling. Subsequent injections with an adequate dose of BTX type A (BTX-A) did not show any clinical response either, although no antibodies to BTX-A were detected. Besides the unanswered questions of dosing and distribution, a second possible explanation could be that BTX-B gave rise to non-neutralizing antibodies that cross-react with BTX-A. The resulting immune complexes could be taken up by phagocytes and, thereby, impede clinical response.     

肌电图引导下A型肉毒毒素治疗不同类型痉挛性斜颈的临床研究

目的：探讨A型肉毒毒素（BTX-A）局部注射治疗不同类型原发性痉挛性斜颈的疗效。方法：在肌电图引导下,对24例痉挛性斜颈患者行BTX-A局部肌肉注射,按其临床类型分组比较疗效及不良反应。结果：全部患者治疗后Tsui量表评分均明显下降,混合型改善程度更明显。所有患者均未见严重不良反应。结论：肌电图引导下BTX-A治疗不同类型痉挛性斜颈均有效,且安全。     

Botulinum toxin A relieved neuropathic pain in a case of post-herpetic neuralgia

Botulinum toxin type A (BTX-A) has been widely used in many clinical disorders including migraine, cervical dystonia, etc. The use of BTX-A in neuropathic pain, however, is uncommon, and the application of the anti-nociceptive effect of botulinum toxin is emerging. Here we report a case of an 80-year-old man who suffered from severe pain of post-herpetic neuralgia which was refractory to the usual therapies. However, this neuropathic pain was dramatically relieved by multiple BTX-A injection and the pain relief lasted 52 days.     

肌电图引导局部肌肉注射A型肉毒毒素治疗痉挛性斜颈的疗效观察

目的 观察肌电图(EMG)引导局部肌肉注射A型肉毒毒素(BTX-A)治疗痉挛性斜颈(CD)的疗效.方法 应用EMG检查19例CD患者头颈部152块肌肉,针对放松状态下出现的多频群放电位的114块靶肌肉进行BTX-A局部肌肉注射;治疗前后分别采用Tsui量表对病情和疗效进行评估;随访观察疗效持续时间以及不良反应.结果 治疗后EMG发现靶肌肉5块;根据Tsui量表评分,治疗后总有效率第1周为47.3%,第2周为78.9%,第3、4周均为94.7%;随访显示疗效平均保持10个月;不良反应轻微,均在4周内自行缓解.结论 EMG引导局部肌肉注射BTX-A治疗CD安全有效.     

Botulinum toxin type A: new therapeutic directions

Intramuscular injections of botulinum toxin type A (BTX-A) have been used successfully to treat disorders such as cerebral palsy and cervical dystonia for many years. New and exciting directions for the toxin are currently under clinical investigation for a number of unlicensed indications including tension-type headache, myofascial pain and hyperhidrosis. Although research on BTX-A is prolific, there is still much to be learnt regarding the toxin's mode of action, clinical application and perhaps more importantly, its place in the overall treatment strategy implemented by physicians to ensure treatment is a success for both the patient and the physician. This review will focus on these issues, by outlining some of the future directions for BTX-A research.     

Jaw-opening oromandibular dystonia secondary to Wilson's disease treated with botulinum toxin type A

We have reported a case series of five patients with jaw-opening oromandibular dystonia secondary to Wilson's disease (WD), in which the patients were treated with botulinum toxin type A (BTX-A). In all cases, dystonia score was partially reduced three weeks after injections. The most common side effect was transient mild dysphagia. This preliminary study showed that jaw-opening oromandibular dystonia in WD may be partially responsive to the use of BTX-A.     

Molding the sensory cortex: spatial acuity improves after botulinum toxin treatment for cervical dystonia.

Disorganization of sensory cortical somatotopy has been described in adult onset primary torsion dystonia (AOPTD). Although botulinum toxin type A (BTX-A) acts peripherally, some studies have suggested a central effect. Our primary hypothesis was that sensory cortical reorganization occurs after BTX-A treatment of AOPTD. Twenty patients with cervical dystonia and 18 healthy age-matched control patients had spatial discrimination thresholds (SDTs) measured at baseline and monthly for 3 months. Mean baseline SDT (+/-SD) was 1.75 +/-0.76 mm in the dystonia group, greater than the control group mean of 1.323 +/- 0.45 mm (P = 0.05). Mean control group SDT did not vary significantly over time. A transient improvement of 23% from baseline (P = 0.005) occurred in the dystonia group 1 month after injection, which did not positively correlate with changes in physician and patient ratings of torticollis severity. The presumed mechanism of SDT improvement is a modulation of afferent cortical inputs from muscle spindles. Society.     

Factors affecting the health-related quality of life of patients with cervical dystonia and the impact of botulinum toxin type A injections

The purpose of this study was to analyze the health-related quality of life (HRQL) of patients with cervical dystonia (CD) and the impact of botulinum toxin A (BTX-A) therapy in these patients. The authors recruited 101 patients with CD, all previously treated with BTX-A. Both before and 4 weeks after injection of BTX-A the patients were assessed using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), a Visual Analogue Scale for pain (VAS: 0-100%), the Short Form 36 health survey questionnaire (SF-36), and the Montgomery-Asberg Depression Rating Scale (MADRS). A control group of 84 healthy volunteers was also evaluated. The patients? baseline SF-36 scores were worse in all the domains when compared with those of the controls. Depression was found in 47.5% of the patients. Improvements were noticed 4 weeks after the single BTX-A injections in all the SF-36 domains, and in the VAS, TWSTRS and MADRS scores. The TWSTRS results did not correlate with any of the SF-36 subscores. Stepwise backward regression analysis revealed depression as the main predictor of poor HRQL, as well as female sex, poor financial situation, and living alone. On contrary, longer treatment with BTX-A was associated with better scores. Cervical dystonia has a marked impact on HRQL and treatment with BTX-A injections has a beneficial effect, seen both in objective and in subjective measures. Depression in CD patients is a main predictor of worse HRQL.     

Long-term remission of idiopathic cervical dystonia after treatment with botulinum toxin

Botulinum toxin type A (BTX-A) treatment for cervical dystonia is traditionally considered a purely symptomatic treatment. BTX-A blocks acetyl choline exocytosis for 3-6 months and most patients require reinjection after this period. We report on 6 patients (mean age 41.6 years, range 18-69) with idiopathic cervical dystonia who were treated with BTX-A injections and became asymptomatic for 2-4 years. Four patients showed remission after the first BTX-A treatment, 1 patient after the second set of injections and 1 after the third session. Amelioration of neck dystonia was observed within 1-4 weeks after the last BTX-A treatment and all 6 patients are symptom-free, off antidystonic medications for over 2 years. The possibility that BTX-A treatment may increase the chances of development of clinical remission in patients with idiopathic cervical dystonia is discussed.     

Aspects of the complexity of cervical dystonia

Most cases of cervical dystonia (CD) can easily be treated by injections of botulinum toxin A (BTX-A) into a few cervical muscles among which the splenius capitis, the semispinalis capitis the levator scapulae and the scalenii muscles are the most important ones whereras the trapezius and the sternocleidomastoideus muscles are of less importance. However, in some cases of CD the treatment of these easily injectable muscles does not lead to a satisfactory clinical outcome. Damage of and compensatory increase of connective tissue in muscles, additional activation of non-injected muscles by special motor tasks as lying, sitting, standing, walking and speaking and involvement of deep muscles remaining usually untreated may add to the complexity of treatment of cervical dystonia.     

Predictable variables for short- and long-term botulinum toxin treatment response in patients with cervical dystonia

We retrospectively evaluated 118 patients with cervical dystonia (CD) treated with botulinum toxin type A (BTX-A) for the following variables: gender, age at evaluation, age at symptom onset, disease duration, presence of head/neck pain and/or tremor, pattern of head deviation, disease progression (spreading of symptoms), etiology (primary vs. secondary), pretreatment with oral medication, and Tsui score. We investigated whether these parameters could predict the clinical outcome in a short- (<30 days) and long-term basis. On short-term treatment, there were no clinically significant differences between BTX-A responsive and non-responsive patients. On long-term treatment, however, intake of oral medication previously to BTX-A injection and higher Tsui scores were predictors of favorable response. These results suggest that the greater CD severity the more likely patients will respond to BTX-A.     

Low-dose botulinum toxin-a treatment of cervical dystonia - a double-blind,randomized pilot study

The purpose of the study was to evaluate the clinical efficacy of low-dose botulinum toxin (BTX) treatment of cervical dystonia in a double-blind, randomized pilot study. Thirty-one patients with cervical dystonia and a minimum of 2 previous Dysport treatments received either a mean total target dose of 547 +/- 113 mouse units (MU) (group A, 500 MU Dysport/ml) or a 4-times-diluted preparation 130 +/- 32 MU (group B, 125 MU Dysport/ml). Assessment was made before and 4 weeks after the injection using Toronto Western Spasmodic Torticollis Rating Scales (TWSTRS). Additionally, a self-response scale evaluated the patients' subjective condition for 12 weeks after injection. TWST rating before and after injection revealed comparable clinical improvement in both groups. The severity of cervical dystonia at study entry had no effects on therapeutic effects of either preparation. Self-rating revealed comparable subjective improvement in both groups; however, 3 patients of group B received reinjections due to insufficient effects of the injection. Our findings suggest that low-dose treatment of cervical dystonia with Dysport may be clinically effective during maintenance therapy, at least for a limited period of time. Long-lasting effects of previous Dysport treatments at conventional doses and possibly improved diffusion of a highly diluted toxin preparation may have contributed to the effects of the low-dose regimen. Our data emphasize the need for further studies in order to clearly identify optimal toxin preparations for therapeutic uses of BTX-A in neurologic disorders.     

Change in the pattern of cervical dystonia might be the cause of benefit loss during botulinum toxin treatment

The muscular patterns of cervical dystonia were identified by polymyographic recordings in 76 patients before botulinum toxin treatment. The leading muscles were considered to be those which started dystonic movement and which showed constant and maximal activity during all dystonic movements. The dystonic muscles were repeatedly treated by local Injections of botulinum toxin. Sixteen patients showed (after repeated injections) loss of the benefit of local applications of botulinum toxin after various periods of time. Repeated polymyographic recordings were performed in these patients during the loss of the benefit of injected botulinum toxin. In four patients repeated polymyographic recordings showed an Identical pattern of cervical dystonia, but the activity of previously injected muscles was apparently decreased. In 12 patients only minimum or no activity was recorded in muscles which had previously been treated with botulinum toxin, but the pattern of cervical dystonia was changed. Different patterns of cervical dystonia with different leading muscles, but with identical directions of head deviation, were observed in six patients. In another six patients, the head deviation direction was to the opposite side and was accompanied by a change of the leading muscle and a change of the muscular pattern of dystonia. These results suggest either that dystonic activity from the cerebral generator changes to new effectors during the peripheral blockade of primary dystonic muscles, or that a change of generators at different levels of the CNS occurs. It may be neccessary to carry out repeated polymyographic recordings throughout the period of loss of benefit of previously successful local botulinum toxin injections.     

Polyradiculoneuritis after botulinum toxin therapy for cervical dystonia

A 40-year-old man with cervical dystonia developed an acute inflammatory demyelinating polyradiculoneuritis after botulinum toxin type A treatment. Some cases of idiopathic brachial plexopathy and polyradiculoneuritis have been reported to date. Although a causal relationship is not firmly established, the clinical temporal profile suggests a pathogenic relationship. In patients with cervical dystonia, further use of type A botulinum toxin should be considered contraindicated, and the use of another type of botulinum toxin should be taken into consideration.