Botulinum toxin type A (Dysport) has been shown in European studies to be a safe and effective treatment for cervical dystonia. This multicenter, double-blind, randomized, controlled trial assessed the safety and efficacy of Dysport in cervical dystonia patients in the United States. Eighty patients were randomly assigned to receive one treatment with Dysport (500 units) or placebo. Participants were followed up for 4 to 20 weeks, until they needed further treatment. They were assessed at baseline and weeks 2, 4, 8, 12, 16, and 20 after treatment. Dysport was significantly more efficacious than placebo at weeks 4, 8, and 12 as assessed by the Toronto Western Spasmodic Torticollis Rating Scale (10-point vs. 3.8-point reduction in total score, respectively, at week 4; P < or = 0.013). Of participants in the Dysport group, 38% showed positive treatment response, compared to 16% in the placebo group (95% confidence interval, 0.02-0.41). The median duration of response to Dysport was 18.5 weeks. Side effects were generally similar in the two treatment groups; only blurred vision and weakness occurred significantly more often with Dysport. No participants in the Dysport group converted from negative to positive antibodies after treatment. These results confirm previous reports that Dysport (500 units) is safe, effective, and well-tolerated in patients with cervical dystonia.

We enrolled and treated 122 patients with idiopathic cervical dystonia in a double-blind, placebo-controlled safety and efficacy study of botulinum toxin type B (BotB). Both A-responsive and A-resistant patients were enrolled. Patients received intramuscular injections of either BotB (2,500 U, 5,000 U, or 10,000 U) or placebo. The primary outcome measure of efficacy was the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS)-Total score at 4 weeks following study drug administration. Secondary measures of efficacy were TWSTRS-Severity, -Disability, and -Pain subscale scores, and Analog Pain Assessment, Investigator Global Assessment, Patient Global Assessment, and Sickness Impact Profile scores. Duration of effect was estimated with an intent-to-treat analysis of responders. Safety measures included clinical parameters, laboratory tests, and adverse events. The primary and most of the secondary analyses indicated a statistically significant treatment effect and a dose response. BotB is safe, well tolerated, and efficacious in the treatment of cervical dystonia at the doses tested.

Elevated amounts of antibodies specific for acetylcholine receptors were detected in 87 percent of sera from 71 patients with myasthenia gravis but not in 175 sera from individuals without myasthenia gravis, including those with other neurologic or autoimmune disease. Antireceptor antibodies were not directed at the acetylcholine binding site of the receptor. Presence or titer of antibody did not appear to correlate with age, sex, steroid therapy, or duration of symptoms. Myasthenia gravis patients with only ocular symptoms had lower antibody titers, while the majority of titers in myasthenia gravis patients with thymoma exceeded the median titer of the myasthenia gravis group as a whole. Assay of antireceptor antibody should prove a useful test in the diagnosis of myasthenia gravis.

Immunoresistance (Ab+) to botulinum toxin type A (BTX‐A) has been a serous concern since the introduction of BTX‐A in the treatment of dystonia and other disorders associated with abnormal muscle contractions. We studied seven patients who developed Ab+ and later reverted to antibodynegative (Ab‐) status. These seven patients, six women (mean age, 56 years; range, 41–80 years), with an average duration of dystonia for all patients of 197 months (range, 84–360 months), received a total mean cumulative dose of 1659 units (U) (range,810‐1975 U), with an average dose of 207 U per visit. All of these patients became unresponsive to BTX‐A treatment and became Ab+ as determined by mouse bioassay. Their response to BTX‐A after they revertedd to Ab‐ was analyzed. The average latency between the initial BTX‐A treatment and development of Ab+ was 27 months (range, 15–43 months). The average duration between the detection of Ab+ status and subsequent reversal to Ab‐ status was 30 months (range, 10–78 months). Six of these Ab‐ patients were reinjected with BTX‐A, and all six benefited from repeat injections comparable with their earlier response. Three patients lost their clinical response to subsequent injections and were found to be again Ab+. Two of the five patients who became immunoresistant to BTX‐A received botulinum toxin type F (BTX‐F) injections and one patient received a single session of BTX‐B with improvement in their symptoms. In conclusion, this unique group of patients who were Ab+ and became Ab‐ responded favorably to repeat BTX‐A injections, but some lost the benefit with subsequent injections. These observations suggest that the anamnestic immunologic response to BTX‐A can wane, but can be reactivated by repeat BTX‐A treatments. The presence of antibodies did not interfere with the response to BTX‐F or BTX‐B injections, thus confirming the antigenic specificity of various BTX serotypes.

The natural history of cervical dystonia (spasmodic torticollis) was investigated in a population-based study in Rochester, Minnesota. Eleven new cases were identified with onset during the 20-year period 1960-1979. The overall incidence rate was 1.2 per 100,000 person-years (95% confidence interval 0.5-1.9) with a female:male ratio of age-adjusted incidence rates of 3.6:1. A unitary etiology was not apparent: injury antedated onset in four of the 11 patients, whereas six had documented thyroid disease and four had diabetes. A family history of movement disorder was recorded for only one subject. Only one of the cases would have been classified as moderate in severity; the others were mild. In follow-up through 1993, progressive disability was noted in only two patients, and two others went into remission. Three cases of intracranial aneurysm were confirmed, two of which produced fatal subarachnoid hemorrahage. A third death was due to amyotrophic lateral sclerosis.