Evaluation of the PaCER Algorithm for Postoperative Subthalamic Nucleus Deep Brain Stimulation Electrode Localization.

Deep Brain Stimulation (DBS) is an established therapy for many movement disorders. DBS entails electrical stimulation of precise brain structures using permanently implanted electrodes. Following implantation, locating the electrodes relative to the target brain structure assists patient outcome optimization. Here we evaluated an open-source automatic algorithm (PaCER) to localize individual electrodes on Computed Tomography imaging (co-registered to Magnetic Resonance Imaging). In a dataset of 111 participants, we found a modified version of the algorithm matched manual-markups with median error less than 0.191 mm (interquartile range 0.698 mm). Given the error is less than the voxel resolution (1 mm3) of the images, we conclude that the automatic algorithm is suitable for DBS electrode localizations.Clinical Relevance- Automated DBS electrode localization identifies the closest electrode to the target brain structure; allowing the neurologist to direct electrical stimulation to maximize patient outcomes. Further, if none of the electrodes are deemed suitable, localization will guide re-implantation.

Can pedobarography predict the occurrence of heel rocker in children with lower limb spasticity?

BACKGROUND: Pedobarography software calculates the centre-of-pressure trajectory in relation to the foot to quantify foot contact patterns. This study presents two new pedobarography measures using the centre-of-pressure trajectory to assess heel rocker. METHODS: To validate these pedobarography measures against 3D gait analysis, emed®-x and Vicon Nexus gait analysis data were captured from 25 children aged 8-16 years (11 male) with unilateral (n = 18) and bilateral (n = 7) cerebral palsy or acquired brain injury. 3D gait analysis identified whether heel rocker was intact (n = 22 feet) or absent (n = 28 feet) based on centre-of-pressure at initial contact and the ankle kinematic curve between 0 and 2% of the gait cycle. Pedobarography measures calculated from the initial centre-of-pressure point were the distance to the heel (point of initial contact) and to the most posterior point of the trajectory (rollback), reported as a percentage of foot length. FINDINGS: The median point of initial contact in limbs with an intact heel rocker was 9% (range 7-12%) and median rollback was 0% (range 0-0.2%), whereas the median point of initial contact in limbs with an absent heel rocker was 58% (range 8-78%) and rollback was 18% (range 0-40%). Point of initial contact is the more accurate method for predicting heel rocker, with a threshold of 14% of foot length identifying the correct heel rocker status in 94% of cases. INTERPRETATION: Point of initial contact can assess heel rocker with high accuracy. Both point of initial contact and rollback provide sensitive information on foot strike pattern, enhancing the utility of pedobarography.