Botulinum toxin in the treatment of writer's cramp.

Forty-four patients with disabling writer's cramp (WC) and one with a musician's cramp were treated with botulinum toxin (BT) injections for a mean period of 12 (range, 3-48) months. The forearm muscles causing the dystonic position were identified by inspection while writing; BT was then administered under electromyographic (EMG) guidance. The degree of improvement in writing and amelioration of pain were rated with self-assessment scales. Patients reported significant improvement in writing after 56% treatment sessions (TS) and in pain after 62% TS. Mild weakness occurred after 32% TS. Twenty-nine patients discontinued treatment, generally after the initial BT injection. In 16 patients who remained on treatment with a mean follow-up of 21 (range, 3-48) months, the improvement in writing and pain was present after 76 and 79% of the TS, respectively. We conclude that BT injections offered a worthwhile and sustained functional improvement to 36% of our patients with WC.