We have been studying the efficacy of local injections of botulinum toxin for the treatment of different types of focal dystonias. Botulinum toxin injected in small doses directly into muscle, binds to and inactivates the neuromuscular junction. Dystonic contraction is decreased and function improves Treatment is well-tolerated with minimal side effects. We have also been using botulinum toxin to study the physiology of focal dystonias. We have continued the treatment of patients with writer's cramp. These patients are active participants in physiology protocols including transcranial magnetic stimulation, PET, microneurography and somatosensory evoked potentials studies. We have demonstrated that immediate exercise following injection in writer's cramp patients leads to greater loss of strength. We continued to study the long-term effects of botulinum toxin type F for patients who lose response to type A due to antibodies and for patients who never responded to type A despite adequate doses. Two patients who previously responded became resistant to the effects of botulinum toxin F. These responses are being investigated with testing for botulinum toxin F antibodies.
