[Treating writer's cramp: 14 years' experience with botulinum toxin]

Writer's cramp is a focal dystonia; treatment remains disappointing. We report our 14-year experience with a population of 119 patients aged between 18 and 85 years (average age 43 years).

Treatment was based on botulinum toxin injections (Dysport) and physiotherapy. Patients were reviewed every four to six months with clinical and video evaluation by three different observers and subjective analysis of the treatment efficiency by the patient (score of 1 to 3). The post-injection deficit, if present, was also quantified.

In the group treated with toxin and physiotherapy, cramps improved (score 2 and 3) in 61.6% of patients; a majority of patients (n=14) reported they were moderately satisfied (score 2). In the group treated with toxin alone, 37.9% of patients were improved (score 2 and 3) with a majority (n=18) very satisfied reporting normal writing (score 3). Age was not a predictor of therapeutic response. Good results were obtained with injections of the flexor carpi radialis followed by flexor digitorum profundus II and III and the flexor pollicis longus. Seventy-one per cent of injections caused moderate muscle weakness, minimally disabling compared to the benefit of injections. Twenty-seven patients were followed for more than two years and three patients, who had achieved score 3 with excellent response, were followed for 14 years with very efficient repeated injections. If the injections were not effective the first time, we re-assessed the situation and adjusted the injections; we considered that toxin treatment was unsuccessful after three injections without benefit.

The choice treatment for writer's cramp remains well-targeted injections of botulinum toxin. Physiotherapy is useful when the toxin injections are ineffective in completely improving writing. This requires close cooperation between the injector, the physiotherapist and the patient.