Surgical Treatment of Dystonia

Abstract

Neurosurgical operations for the treatment of dystonia patients comprise extracerebral and intracerebral procedures. Several retrospective studies using selective peripheral denervation and selective myotomy for the treatment of patients with cervical dystonia (CD) reported functionally relevant improvements in the order of 50–60 % according to different, sometimes descriptive assessment scales. In the only prospective study performed to date, the same surgical technique improved scores of the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) significantly but to a lesser degree by 30 %. Most frequently observed side effects were sensory loss in the area of the dissected nerves and muscle weakness. Pallidal deep brain stimulation (GPi-DBS) seems to be more effective in CD patients than extracerebral surgery. In retrospective studies, improvements in TWSTRS subscales (severity, disability, pain) ranged from 55 to 63 %, 59 to 69 % and 50 to 58 %, respectively. Two prospective studies documented for most subscales improvements of >60 %. Patients with generalised or segmental dystonia treated in controlled, randomised studies responded to GPi-DBS with an average improvement of 50 %. Even though less frequently documented compared to primary dystonia, also in rare dystonia types such as Meige syndrome, myoclonus dystonia or dystonia secondary to heterodegenerative diseases, pallidal neuromodulation seems to be effective. Despite medication-induced tardive dystonia, which seems to be as responsive as primary dystonia, the application of GPi-DBS in patients with secondary dystonia is still an individual case-by-case decision.