Demonstration of Microsurgical Technique and Nuances for the Resection of a Midbrain Tectal Glioma via the Transcollicular Approach: 3-Dimensional Operative Video.

Tectal gliomas are a rare subset of intrinsic brainstem lesions. The microsurgical resection of these lesions remains a major challenge.1,2 Transcollicular approaches on one side, via the superior or inferior colliculi or both, are neurologically well tolerated without obvious or major auditory or oculomotor consequences. However, any postoperative acute visually triggered saccadic abnormalities caused by iatrogenic superior colliculus damage generally resolve during the postoperative period, as other oculomotor structures compensate for these functions in unilateral lesions.  In this surgical video, we present a 37-yr-old man with long-standing seizures, new onset headaches, progressive ataxic gait, and imbalance. Magnetic resonance imaging (MRI) showed a circumscribed nonenhancing dorsal midbrain cystic mass with compression on the aqueduct causing hydrocephalus. The lesion had a low signal intensity on T1-weighted images and a high signal intensity on T2-weighted images. The patient first underwent an endoscopic third ventriculostomy. Although his headaches greatly improved after the third ventriculostomy, he remained quite symptomatic in terms of gait imbalance and ataxia. The patient underwent a supracerebellar, infratentorial, transcollicular approach for resection of the tectal tumor. Simultaneously, motor and somatosensory evoked potentials were monitored.  Both the surgery and the postoperative course were uneventful, with postoperative MRI showing gross total resection of the mass, and histopathology indicating a WHO (World Health Organization) grade I pilocytic astrocytoma. The patient continued to do well without recurrence at 2-yr follow-up.  In this video, we demonstrate step-by-step microsurgical techniques for resecting these challenging tectal gliomas via the infratentorial-supracerebellar-transcollicular approach. The patient consented to the procedure and publication of his images.