Long-term effect of botulinum toxin on impairment and functional health in cervical dystonia.

We investigated the long-term effect of botulinum toxin type A (BTA) on impairment as well as functional health in terms of disability, handicap, and quality of life in 64 patients with cervical dystonia. These patients, who first participated in a double-blind trial, were followed for another 12 months. Fifty-four patients continued treatment after 12 months of follow-up and showed improvement on all scales. Furthermore, this effectiveness appeared to increase during follow-up, which suggests a cumulative clinical effect of BTA.