DBS can improve abnormal postures, tremor and pain due to dystonia. DBS can thereby improve function such as eating and driving and improve quality of life. DBS can reduce the need to take dystonia medication and botulinum toxin injections – however, if needed, such treatments can be continued after having DBS.

The benefit of DBS on dystonia is not immediate but accrues over months and years. The degree of benefit from DBS on dystonia is variable and hard to predict, ranging from no effect to almost total relief. Primary dystonia (where there is no brain lesion and intellectual function is normal) tends to respond much better than secondary dystonia (where there is a brain lesion such as due to cerebral palsy or a previous stroke) Dystonia of the limbs (arms and legs) usually improves more than dystonia of the midline (e.g. speech and neck). For primary generalised dystonia, improvement is often above 50% whereas for primary dystonia affecting only the neck (cervical dystonia/torticollis) improvement averages around 40%. For patients with cerebral palsy, the improvement for dystonia averages around 25%. DBS is not a cure for dystonia – and dystonia recurs if stimulation is switched off. However, the benefit of DBS usually remains as long as stimulation continues (it does not usually wear off).

For dystonia, we almost always implant DBS into the Globus Pallidus interna (GPi).

Side effects from this type of stimulation occur uncommonly and usually rapidly resolve once recognised and DBS is adjusted. Side effects can include muscle spasms and tingling (from spread of DBS to a neighbouring brain region) and slower movement.

The greatest issue with DBS for dystonia is not usually side effects – but incomplete response of the dystonia.