DIPG-38. CORTICOSPINAL TRACT TOLERANCE TO CATHETER POSITIONING FOR CONVECTION ENHANCED DELIVERY IN THE BRAIN STEM

Abstract

Abstract INTRODUCTION: Convection enhanced delivery (CED) has recently been explored as a therapeutic strategy for children with diffuse intrinsic pontine glioma (DIPG). An anterior or supratentorial approach for catheter positioning risks conflict with descending white matter bundles where they become concentrated in the internal capsule and crural pyramid. We describe our experience planning catheter trajectories in the context of eloquent structures and outcomes this patient population. METHODS: As part of a Phase 1 clinical trial using CED with 124I-8H9, a radiolabeled monoclonal antibody (NCT01502917), a flexible step-design infusion catheter (Brainlab Flexible Catheter, BrainLab, Munich, Germany) was surgically placed via a supratentorial approach. Surgical planning was conducted based on 3D T1, T2, and SWI sequences. A fully compatible MR-guidance platform was used for trajectory planning catheter deployment. A neurologic exam was performed immediately post-procedure, prior to initiating infusion, to assess for procedure-related deficits. Intra- and post-procedural MR images were analyzed for the anatomic position of catheter trajectories. Conflicts between the catheter tract and the posterior limb of the internal capsule and the pyramid of the crus cerebri were recorded. Correlation between motor deficits and the catheter path was evaluated. RESULTS: Thirty-three catheter insertions were performed for 28 children with DIPG. One patient experienced a slight worsening of an existing ipsilateral facial palsy likely related to the course of facial nerve fibers in the brainstem. The posterior limb of the internal capsule and the pyramid of the crus cerebri frequently overlapped the catheter tract without incident. CONCLUSIONS: Transgression of descending corticospinal motor tracts by catheters for intracranial infusion is acceptable. We observed that a supratentorial approach to the brainstem crossing eloquent fibers resulted in one neurologic deficit. There does not appear to be a functional risk requiring a need for avoidance of the dominant motor fiber tracts during trajectory planning.