Treatment of focal dystonias of the hand with botulinum toxin injections.

The effects of botulinum toxin injections have been studied on 19 patients with hand dystonia. The dystonic muscles were identified by clinical examination and EMG findings of localised bursts of muscle activation with fine wire electrodes during the tasks that precipitated the dystonia. Injections into the most active muscles were given to each patient every 2 weeks in increasing doses (up to 20 U the first week, up to 40 U the second week, and up to 80 U the third week) until performance improvement was achieved. Subjective improvement of cramping, pain and/or tension was associated with temporary weakness in injected muscles. Benefit was seen in 16 patients, lasted between 1 and 6 months, and was reproducible.