218 Target Selection for Deep Brain Stimulation in Children with Secondary Dystonia Utilizing Temporary Depth Electrodes for Stimulation and Chronic Recording

Abstract

Abstract INTRODUCTION The optimal target for deep brain stimulation (DBS) treatment in children with secondary dystonia is not known, and the target may vary depending on the etiology and anatomic distribution of injury in each child. We present a new technique for determining optimal neuro-anatomical targets in these patients. METHODS Up to ten depth electrodes are implanted in each child in multiple brain regions, including bilateral STN, GPi, and the VLa (Vo), VLp (Vim) and VPL nuclei of the thalamus. Each electrode had both high-impedance micro contacts to identify single unit firing and macro contacts for identifying local field potentials and for performing test stimulation. Children were monitored for up to one week with continuous recording from all electrodes and intermittent test stimulation at bilateral contact pairs. RESULTS >No single consistent pattern of abnormality was found. Most often, single-unit recording showed high firing rates in GPi, and dystonic movement correlated with activity VLa or VLp. The optimal stimulation target varied between children, with rapid improvement of dystonic postures during stimulation in either VLa, VLp or VPL. Stimulation of STN caused resolution of spasms during sleep in one child. Stimulation in GPi did not produce an immediate effect during the recording period, consistent with known latency of treatment effect. All of the children were implanted with up to 4 permanent stimulation leads connected to implanted pulse generators. Preliminary clinical observations show significant beneficial effect in all children. CONCLUSION This new method of DBS targeting identified targets that varied between children. Early response to therapy suggests a beneficial effect that exceeds what would be expected for GPi stimulation alone. This technique may increase the effectiveness of DBS in secondary dystonia and may allow application to a broader range of conditions in children not previously known to respond to stimulation.