The "Canopy Approach": Case Series Using Immersive Virtual Reality for Bottom-Up Target-Based Preoperative Planning in Pediatric Neurosurgery

Abstract

Background: Virtual reality (VR) is increasingly used for trajectory planning in neurosurgery.

Objective: To describe a case series showing the application of immersive VR involving both "top-down" from skull to lesion and "bottom-up" from lesion to skull approaches for trajectory planning in pediatric neurosurgical patients.

Methods: We detail the preoperative and intraoperative application of VR and clinical courses of 5 children (aged 7-14 years) with anatomically challenging intraparenchymal lesions that posed operative risks to nearby vascular anatomy and fiber tracts. Preoperative planning consisted of standard presurgical evaluation with computed tomography and magnetic resonance imaging used to render 3-dimensional models that could be viewed and manipulated using desktop software and immersive VR headsets and hand controllers by the surgeon and family. Patient satisfaction was evaluated by survey. Surgical outcomes were degree of seizure control or extent of resection.

Results: Three patients underwent lesion resection and 2 laser ablation. Modifications to 2-dimensional and "top-down" VR trajectory plans were made after "bottom-up" navigation in all cases. All families reported that the VR enhanced their understanding of the procedure. There were no complications, and no patients suffered permanent neurological deficits postoperatively. Gross total resection was achieved in all lesional cases, and patients with epilepsy achieved seizure freedom at 2 years postoperatively.

Conclusion: Immersive VR allows operative corridors to be virtually traveled and viewed from a "top-down" and "bottom-up" perspective, as if looking up from under a forest canopy of overlying anatomy, for optimal trajectory planning and improvement of family understanding in pediatric neurosurgery.

Keywords: Pediatric brain tumor; Pediatric epilepsy surgery; Pediatric neurosurgery; Preoperative planning; Virtual reality.

FIGURE 1.

Hemorrhagic parietal synovial sarcoma. A, Axial noncontrast computed tomography shows a hyperdense lesion (arrow), intraparenchymal hematoma (arrowhead), interhemispheric hemorrhage, and 6 mm of midline shift. Postoperative B, Axial, C, Coronal, and D, Sagittal T1-weighted MR images show a residual contrast-enhancing lesion (arrows) along the superior sagittal sinus. E, Three-dimensional reconstruction of blended computed tomography and magnetic resonance imaging recreates the hemorrhagic tumor resected during the patient's first surgery (crimson) and residual tumor underlying the craniotomy edge (green). F, A “bottom-up,” intracranial vantage point reveals margins of the tumor underside of the superior sagittal sinus extending contralaterally.

FIGURE 2.

Left temporal neuroepithelial tumor of the young (PLNTY). A, Preoperative axial T1 and sagittal T2-weighted magnetic resonance B. Virtual reality 3-dimensional view from a posterior-lateral approach with the proposed operative trajectory to lesion (red). The optic radiations travel superiorly away from the lesion. C, “Bottom-up” view reveals a serpiginous vessel along the deepest surface of the lesion with the proposed posterior trajectory (turquoise arrow). D, High-magnification view from a lateral view shows a possible en passage vessel (arrows) traveling through the lesion and toward the optic radiations. The deep serpiginous vessel is seen in silhouette through a partially translucent lesion. E, Intraoperative image reveals a fully dissected en passage vessel (arrow) and the deep serpiginous vessel (arrowheads).

FIGURE 3.

Left parietal focal cortical dysplasia. A, Coronal and sagittal fluid-attenuated inversion-recovery sequences reveal a hyperintense transcortical, “transmantle sign” (highlighted circle). B, Parietal entry point and C, “Canopy Approach” views of an optimal corridor to the lesion avoiding the neighboring motor tracts. D, Design of the potential transcortical approach using reconstructed parenchymal anatomy. E, Reconstructed skull and scalp planes used for planning optimal head positioning.

FIGURE 4.

Trajectory planning for laser ablation of a hypothalamic hamartoma. A, Low-magnification trajectory view of the proposed laser fiber path. B, High magnification of the trajectory path reveals a potential contrast-enhancing vessel along trajectory. C, Side/intracranial and D, “Canopy” views of trajectory with on-the-fly, 3-dimensional adjustment of trajectory points.

FIGURE 5.

Stereo-EEG electrode placement and trajectory planning for laser ablation of the cingulate gyrus ictal onset zone. A, “Canopy” views of sEEG electrodes placed in the anterior (Ant CG) and middle (Mid CG) gyrus. Preplanned trajectories are blended with implanted sEEG electrodes. B, “Canopy” view of a laser ablation fiber implanted to a middle cingulate gyrus ictal onset zone through a parietal entry point. CG, cingulate gyrus; sEEG, stereo-electroencephalogram.