Long-term follow-up study of chronic deep brain stimulation of the subthalamic nucleus for cervical dystonia.

Objectives. Medically refractory cervical dystonia has recently been treated using deep brain stimulation (DBS), targeting the subthalamic nucleus (STN). There has been limited literature regarding short-term outcomes and no literature regarding long-term outcomes for refractory cervical dystonia following DBS of the STN. Materials and Methods. Two patients with medically refractory cervical dystonia underwent STN DBS. Patients were rated using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) preoperatively and immediately postoperatively as well as just prior to turning on the stimulators and subsequently at 24-48 hours, six months, one, two, and three years after stimulation. Microrecordings were used to identify the STN and substantia nigra reticulata (SNr). Results. Significant immediate and sustained long-term improvements were seen in motor, disability, pain, and total TWSTRS scores. In one patient, only unilateral stimulation was required. The STN and SNr were easily identified as having activity similar to off-state Parkinson's patients. Conclusions. DBS therapy for cervical dystonia utilizing the STN as the surgical target may be novel and may be an alternative target to the globus pallidus internus as supported by this first long-term outcome report. Further studies need to be performed to confirm these conclusions.