There is no cure for primary dystonia, but the symptoms can be managed as in secondary dystonia. Therapeutic options for dystonia include oral medications (anticholinergics, benzodiazepines), botulinum toxin injections, physical therapy, surgery, and clinical trials. Among these treatments, botulinum toxin injections are the most promising therapy for focal dystonia13 and can have short-term beneficial effects to relieve spasms associated with dystonia.
Botulinum toxin type A (BOTOX®) injections are administered, typically every three to four months, for the temporary relief of dystonia. These injections may cause minimal side effects, such as brief muscle weakness. The toxin acts by blocking acetylcholine release at the neuromuscular junction, thus reducing the excessive activation of the involved dystonic muscles. Eventually, the toxin's effects wear off over a three to six month period and the symptoms (spasms, pain) of dystonia reoccur. The involved dystonic muscles are targeted for BOTOX injections using physical examination and/or electromyography (EMG). The number, size, and location of the muscles involved, as well as the dose of BOTOX administered, all affect the efficacy of this treatment. Injections are usually given every three to six months, according to the type of dystonia being treated.
Over the course of botulinum toxin therapy, antibodies may develop against the drug, rendering it ineffective. Frequent dosing intervals (less than three months), the use of "booster" doses, and the use of large doses (greater than 300-400 units) are associated with the development of these antibodies. When there is a suspicion that therapy is not working due to toxin antibodies, a test for antibodies to BOTOX type A may be utilized. The toxin test is designed both to evaluate patients not responding to BOTOX type A therapy and to monitor patients undergoing BOTOX therapy.
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