Dystonia is a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. Primary and secondary dystonias are distinguishable and both can be classified by the extent of body involvement as generalised, focal, segmental, multifocal and hemidystonic. The treatment of primary dystonias involves the exclusion of secondary causes such as drug-induced (particularly common with dopamine blocking agents) and Wilson’s disease. This should be followed by a trial of levodopa, especially in cases of onset in the first 3 decades of life.
Symptomatic oral pharmacotherapy includes anticholinergic agents, baclofen, clonazepam and carbamazepine. The use of intrathecal baclofen infused by a surgically implanted pump has been advocated for intractable axial dystonia. Botulinum toxin A injections have become the treatment of choice of many focal dystonias (e.g. blepharospasm, cervical dystonia, jaw closure dystonia, hyper-adduction laryngeal dystonia). Jaw opening dystonia, writer’s cramp and more complex limb dystonias may also benefit from botulinum toxin A. Paroxysmal kinesigenic dystonias are responsive to phenytoin, carbamazepine, phenobarbital (phenobarbitone), primidone and diazepam. Paroxysmal nonkinesigenic dystonias do not respond as well to these agents and may warrant a trial of other agents such as acetazolamide, clonazepam, oxazepam, baclofen or anticholinergic agents.
Surgical interventions include stereotactic thalamotomy for severe generalised dystonia unresponsive to intensive pharmacological trials, and ‘peripheral’ surgeries designed to address specific types of focal dystonia that are unresponsive to botulinum toxin (e.g. orbital myectomy for blepharospasm and cervical ramisectomy for cervical dystonia). Orthotic devices for limb dystonia, and writing aid devices and other physical therapy measures can provide assistance in selected patients.