Minimally-invasive Parafascicular Surgical (MIPS) Approach for the Management of a Pediatric Third Ventricular Ependymoma: Case Report and Review of Literature.

Minimally-invasive parafascicular surgery (MIPS) has evolved into a safe alternative to access deep-seated subcortical and intraventricular pathologies. We present a case of a port-mediated resection of a pediatric third ventricular tumor. The patient is a 7-year-old male who presented with worsening headache, nausea, vomiting, dizziness, unsteady gait, photophobia, and "blind spots" with positional changes. MRI revealed a large isointense mass, with areas of hyperintensities suggestive intratumoral hemorrhage, centered in the posterior segment of the third ventricle with extension into the aqueduct of Sylvius. The superior frontal sulcus was utilized as an access corridor for the port to the frontal horn of the lateral ventricle en route to the third ventricle. Intraoperative visualization was aided with a 3D exoscopic system. Following cannulation, the tumor was seen within the foramen of Monro and tethered to the thalamostriate vein. Tumor was removed completely, with the exception of small residual attached to the thalamostriate vein, which was left intentionally. A flexible endoscope was placed through the port to verify the absence of residual along the superior wall of the third ventricle. Intraoperative MRI confirmed presence of residual, along with normal postoperative changes, including pneumocephalus. Postoperative MRI revealed cortical recovery along the sulcal path and resolution of ventriculomegaly. The patient improved from baseline, with no remaining visual deficits, headaches, or balance issues. Pathology reported a WHO grade II tanycytic ependymoma. To the best of our knowledge, few cases have reported the utilization of port-based MIPS in pediatric patients.