Long-term treatment of cervical dystonia with botulinum toxin A: efficacy, safety, and antibody frequency. German Dystonia Study Group.

Abstract

Data from 616 patients suffering from idiopathic cervical dystonia were analyzed to determine the efficacy and safety of treatment with botulinum neurotoxin type A (BoNT/A). Since the specific purpose of this study was to determine the long-term effects of this treatment, the analysis focused specifically on the patients (n = 303) having received six or more injections. Statistical analysis of a standardized documentation showed sustained significant benefit as measured by a disease severity score independent of the type of cervical dystonia. Furthermore, pronounced individual differences were found in response to this treatment although initial clinical scores and doses of BoNT/A were similar. There was no indication of previously unknown adverse events, the only risk being the development of serum antibodies against the toxin. As in previous studies on short-term effects of BoNT/A treatment, the most frequent adverse event was dysphagia, which occurred on average 9.7 days after injection and lasted on average 3.5 weeks. While secondary nonresponse was seen in approx. 5% of patients, antibody tests revealed neutralizing serum antibodies in only 2%. On the basis of the present data, therapy of cervical dystonia with BoNT/A seems to be safe and yields good stable results even after 5 years of treatment.