Evoked Potentials During Peripheral Stimulation Confirm Electrode Location in Thalamic Subnuclei in Children With Secondary Dystonia

Abstract

Deep brain stimulation is an elective surgical intervention that improves the function and quality of life in children with dystonia and other movement disorders. Both basal ganglia and thalamic nuclei have been found to be relevant targets for treatment of dystonia in children, including the ventral intermediate nucleus of the thalamus, in which stimulation can control dystonic spasms. Electrophysiological confirmation of correct electrode location within the ventralis intermediate nucleus is thus important for the success of the surgical outcome. The present work shows the evoked potentials response during contralateral median-nerve stimulation at the wrist at low frequency (9 Hz) provides physiological evidence of the electrode’s localization within the thalamus. We show the correlation between evoked potentials and magnetic resonance imaging (MRI) and computed tomography (CT) in 14 children undergoing implantation of deep brain stimulation electrodes for secondary dystonia. High fidelity and reproducibility of our results provides a new approach to ensure the electrode localization in the thalamic subnuclei.

Stereotactic Awake Basal Ganglia Electrophysiological Recording and Stimulation (SABERS): A Novel Staged Procedure for Personalized Targeting of Deep Brain Stimulation in Pediatric Movement and Neuropsychiatric Disorders

“…Although variations in subjects’ anatomy was expected due to differences in underlying pathology, in all cases targeting performed using the Schaltenbrand-Wahren atlas aligned and scaled to the patient's AC-PC line appeared to identify appropriate targets, confirmed by 2 neurosurgeons. We have previously confirmed that this atlas adequately identifies the Vim/Vo boundary in thalamus 23…”

Deep brain stimulation in globus pallidus internus travels to thalamus and subthalamic nuclei along physiological pathways

“…This resulted in approximately 1000 segments per stimulus location, which were finally averaged to increase signal-to-noise ratio [50]. The stimulus-triggered averaging methodology presented by Sinclair et al [50] was repeated for both sets of polarity reversed stimulation settings, which were finally aligned to produce a polarity-reversed average with smaller stimulus and decay artifacts [42, 51, 52], as shown in Figure 2 4 .…”

“…[3]. The position of leads and electrode contacts was determined by alignment of a post-operative computed tomography (CT) scan with the preoperative magnetic resonance image (MRI) detailed anatomic scan [21]. Each implanted lead contains 6 low-impedance (1-2 kΩ) ring macro-contacts with 2 mm height and 5 mm on-center spacing, as well as 10 high-impedance (70-90 kΩ) microwire electrodes (50-µm diameter) referred to as micro-contacts.…”

“…Based on prior studies of clinical efficacy in children with dystonia , typical target regions for DBS include STN and GPi in basal ganglia, ventral intermediate (VIM), VO, and VA thalamic subnuclei [3]. The position of leads and electrode contacts was determined by alignment of a post-operative computed tomography (CT) scan with the preoperative MRI anatomic scan [19,20]. Each implanted lead contains 6 low-impedance (1-2 kΩ) ring macro-contacts with 2 mm height GA1; Hypertonic and hyperkinetic dystonia and 5 mm on-center spacing, as well as 10 high-impedance (70-90 kΩ) microwire electrodes (50-µm diameter) referred to as micro-contacts.…”

Increased movement-related signals in both basal ganglia and cerebellar output pathways in two children with dystonia

“…Electrode location was confirmed by co-registration of preoperative magnetic resonance imaging (MRI) and postoperative computed tomography (CT) scans. Thalamic targeting was confirmed by identification of leads in subnuclei known to have greater or lesser response to median nerve electrical stimulation (9).…”