Responsiveness of idiopathic spasmodic torticollis to botulinum A toxin injection. A critical evaluation of five cases

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.

A comparison of the spread of three formulations of botulinum neurotoxin A as determined by effects on muscle function

The purpose of these experiments was to compare the spread of three formulations of botulinum neurotoxin A. A gelatin/phosphate buffer (C), DysportR (D {0.5 U}, BotoxR (B {0.167 U}), or a purified preparation of botulinum neurotoxin A [Bont A] (BA {0.5 U}) was injected into the tibialis anterior of male, Wistar rats. After 4 days, the adjacent extensor digitorum longus muscle was isolated in situ and the nerve was maximally stimulated to determine contractile properties and the rate of fatigue. There were no differences in body or muscle weights between any of the groups after 4 days of treatment. Maximal twitch and tetanic tensions were decreased reverse similar 25% (p < 0.05) in all treatment groups compared to C. In addition, rate of tension development was significantly less in all treatment groups compared to C but one-half relaxation time and time to peak tension were not different between any groups. Fatigue of the muscle was significantly faster in all groups compared to C but there was no difference between treatment groups. These data indicated that botulinum toxin A injected intramuscularly was likely to spread to adjacent muscles but that the spread was not different between the three formulations tested. The effect of the spread ranged from a slight to a severe reduction in maximal tension but this did not occur in all animals studied. Copyright Rapid Science Ltd

Treatment outcomes in cervical dystonia: a clinimetric study

We reviewed 21 studies (8 blinded and 13 open) on the treatment of botulinum toxin type A for cervical dystonia, directed to the health aspects used to evaluate the patients' response to treatment (Medline search 1985-1993, English language literature). The prerequisite for comparing the treatment results was that studies had to evaluate similar aspects of disease. The ICIDH model, outlined by the World Health Organization in 1980, orders the different health outcomes into distinct classes of disease consequences. Our aim was to order the health outcomes according to the model and, thus, to study the comparability of treatment outcomes. Three differences could be identified between the objective and the subjective instruments. (a) The aspects measured by the subjective instruments varied substantially; of the 22 different subjective instruments identified in 18 studies, 8 measured impairments, 5 disability, and 9 could not be classified according to the ICIDH model. The objective instruments measured impairments. (b) All objective instruments were multiitem, whereas only 2 of 22 subjective instruments could be identified as multiitem. (c) The subjective instruments were generally poorly documented with regard to the number of items, score range, or grading. We conclude that the treatment outcomes can only be compared on the objective level of assessment and with regard to the patients with painful dystonia. The subjective instruments, particularly those focusing on disease-specific disability, deserve further research. The ICIDH model offers a useful framework for selection, improvement, and development of outcome instruments. Because the model clearly demarcates the different consequences of disease, adoption will enhance the comparability of outcomes in cervical dystonia intervention trials.

The effect of botulinum toxin type A injection on compound muscle action potential in an in vivo rat model

Serial measurements were performed on the compound muscle action potential (CMAP) amplitude and the force generated by the rat lower hind limb flexors to investigate the time course of intramuscular injections of botulinum toxin type A (BOTOX). Thirty animals were used in this in vivo rat model. CMAP amplitude and muscle force were measured at predetermined intervals for 28 weeks. Compound muscle action potential amplitude and force declined markedly the first 5 to 7 days after injection of BOTOX but recovered in a near linear manner. The response magnitude and recovery rate were dose-dependent. Recovery of CMAP amplitude preceded recovery of muscle force. No clear evidence of a systemic effect on the untreated leg or a concentration effect was found. CMAP amplitude may be useful in determining optimal timing of repeat injections in treating neuromuscular disorders.

Quantifying how location and dose of botulinum toxin injections affect muscle paralysis

Despite the widespread use of botulinum toxin to treat muscle dystonias, no method exists to quantify muscle paralysis in either human or nonhuman models. In this study we examined how the location, dose, and volume of botulinum injection affects paralysis in the rat tibialis anterior muscle. Paralysis was quantified by electrically stimulating the nerve to the tibialis anterior and then staining sections of the muscle for glycogen. The areas of glycogen-containing fibers represented regions of botulinum action. The results showed that the most important injection technique is to inject botulinum directly into the motor endplate region of a muscle. Injections only 0.5 cm from the motor endplate resulted in a 50% decrease in paralysis. Increases in dose increased paralysis, however, some of that increase was simply due to the increased volume of injection. Thus, delivering toxin in small volumes near the MEP band of a muscle should produce the most effective paralysis.

Drug-induced dysphagia

Dysphagia describes the disability or problems in swallowing a wet or dry bolus properly and is normally associated with an impaired transport of the bolus. Dysphagia can be accompanied by a pain sensation in the chest mostly caused by impaction of the food bolus in the esophagus. Odynophagia describes only the status of painful swallowing without an impairment of the swallow and transport function. Drug-induced dysphagia can be caused in two different ways. First as a normal drug side effect of the pharmacological action of the drug or as a complication of the therapeutic action of the drug. The normal drug side effect is most likely in drugs that affect smooth or striated muscle function or the sensitivity of the mucosa. The drug effect on smooth muscle function that causes dysphagia can be inhibitory or excitatory. Dysphagia is a common clinical symptom in patients with reduced perception of the pharyngeal mucosa which leads to an subjective impairment of swallowing. Dysphagia caused by a complication of the therapeutic action of a drug includes viral or fungal esophagitis in patients treated with immunosuppressive drugs or cancer therapeutic agents, or antibiotics and immunological reactions to certain drugs such as erythema exsudativa multiforme or Stevens-Johnson syndrome. Second, drug-induced dysphagia can be due to medication-induced esophageal injury (MIEI). In most cases this mucosal injury appears to be the direct result of prolonged contact of a potentially caustic drug with the esophageal mucosa. This form of medication-induced esophagitis is most likely to be found in elderly patients and patients with esophageal motility disorders.(ABSTRACT TRUNCATED AT 250 WORDS)