Soletra

The globus pallidus internus (GPi), subthalamic nucleus (STN) and ventral intermediate nucleus (VIM) were selected as the location of surgery, which was decided by a multiple‐member disciplinary team. The locations were determined by using T2 weighted magnetic resonance imaging (MRI) (1.5 T; General Electric Healthcare) and confirmed with intraoperative macrostimulation. Quadripolar DBS electrodes (model 3387 for STN and GPi and 3389 for VIM; Medtronic) were implanted under local anesthesia, and motor function and adverse effects were strictly monitored during macrostimulation. The detailed location of GPi and STN target were mentioned in our previous study.14 VIM target planning started with standard stereotactic coordinates relative to the posterior commissure (PC) on the anterior–posterior commissure (AC‐PC)‐aligned MRI: 10.5‐11 mm lateral to the wall of the third ventricle, 6‐7 mm anterior, and 0 mm dorsal. Patients remained in our hospital for three nights using a 3625 external stimulator for trial stimulation. Permanent IPGs were implanted only after temporary stimulation showed preliminary efficacy. The IPG (Soletra, 37603 or 37612RC; Medtronic) was then implanted subclavicularly under general anesthesia. Postoperative MRI or CT was performed for each patient to confirm the location of the electrodes.

Surgery was performed under isofluorane general anesthesia, in view of the young age of the children. Stereotactic MRI was performed pre-operatively under anesthesia with a Leksell G Frame in place to determine co-ordinates targeted in the postero-latero-ventral GPi. Bilateral electrodes were implanted in each case. The electrodes used are all Medtronic 3389 circumferential electrodes: contacts 0.5 mm apart and 1.5 mm in length. Final electrode placement was confirmed by post-operative stereotactic CT scan, under the same general anesthetic, fused with the intra-operative in-frame pre-surgical MRI. The pulse generator was then inserted (Soletra and Kinetra until 2008, and Activa RC pulse generators thereafter, Medtronic, Minneapolis, MN, USA).
Accuracy of electrode placement within our service has been studied previously (22 (link)). Mean Euclidean distance between final electrode tip position and target position was 2.2 mm with no difference in accuracy between isolated genetic/idiopathic and acquired dystonia cases. No correlation was found between outcome at 1 year and Euclidian distance between target and actual position (22 (link)).