Use of botulinum toxin in the treatment of cervical dystonia.

Idiopathic cervical dystonia, like other adult-onset focal dystonias, has been notoriously difficult to treat. Multiple approaches, including systemic drug treatment with anticholinergics, antidopaminergics, anticonvulsants, muscle relaxants and many other drugs as well as physiotherapy and psychotherapy, usually lead to only temporary amelioration in a minority of patients. Surgical selective EMG-controlled denervation of dystonic neck muscles produces better and, in the hands of some, lasting improvement. However, the procedure is invasive and as such less well accepted by patients. Local injections of botulinum toxin are strikingly successful in improving postural deviation and pain in about 80% of patients. They can be made on an outpatient basis and appear to be safe even over many repeat sessions. Dysphagia is potentially the most serious side-effect but can be decreased in incidence and severity by injecting lower doses, particularly into the sternomastoid. Major drawbacks at present are a lack of prospective data to establish optimal dosage and volume of injection guidelines to preserve good efficacy at a reduced risk of side-effects, and the need to continue indefinitely with repeat injections approximately every 3 months.