Epidural premotor cortical stimulation in primary focal dystonia: clinical and 18F-fluoro deoxyglucose positron emission tomography open study.

The aim of this study was to evaluate the efficacy and safety of epidural premotor stimulation in patients with primary focal dystonia. Seven patients were selected: 6 had cervical dystonia and 1 had right upper limb dystonia. In 2 patients, sustained muscle contractions led to a prevalently fixed head posture. Patients with cervical dystonia received a bilateral implant, whereas the patient with hand dystonia received a unilateral implant. Neurological and neuropsychological evaluations were performed before surgery (baseline), and 1, 3, 6, and 12 months afterward. The Burke-Fahn-Marsden scale (BFMS) and the Toronto Western spasmodic torticollis rating scale (TWSTRS) were administered at the same time points. Patients underwent resting (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scans, before and 12 months after surgery. No adverse events occurred. An overall improvement was observed on the BFMS and TWSTRS after surgery. Patients with prevalently fixed cervical dystonia had a reduced benefit. Presurgical neuroimaging revealed a significant bilateral metabolic increase in the sensorimotor areas, which was reduced after surgery.