Deep Brain Stimulation for Dystonia

Abstract

There is now strong evidence demonstrating that bilateral globus pallidus internus (GPi) stimulation improves motor function and disability in patients with severe primary generalised, segmental or cervical dystonia. The improvement is gradual, typically occurring over a period of about six months, with pain and then phasic components dissipating before the tonic elements of dystonia. Controlled data indicate that the benefits of GPi stimulation are in the order of 40–60% and are sustained at three years. Further work is required to better understand variation in the extent of the response. The procedure is usually performed under general anaesthesia and is well tolerated, although minor and hardwarerelated complications are common. GPi stimulation can also provide useful benefit to selected patients with secondary dystonia, with encouraging results reported for tardive dystonia, myoclonic dystonia and pantothenate-kinase-associated neurodegeneration. Currently, it is not known whether the nucleus ventralis intermedius of the thalamus or GPi is the optimal target for the surgical treatment of writer’s cramp.