Supracerebellar Infratentorial Keyhole Approach in Sitting Position Using 3-Dimensional Exoscope and Angled Endoscope for a Giant Pineal Tumor.

Pineal tumors are rare but surgically challenging due to their deep location and proximity to major veins and brainstem. ^{1 , 2} Getting a biopsy along with an endoscopic third ventriculostomy is essential before surgical resection. ^{3 , 4} The supracerebellar infratentorial approach provides direct symmetrical exposure of the pineal region inferior to the vein of Galen. ^{5 , 6} 3-Dimensional (3D) exoscopes are increasingly used due to better ergonomics, greater depth of field, and equivalent image quality of microscope. The endoscope provides angled optics to visualize hidden areas of tumor adherent to neurovascular structures, avoiding blind dissection. These become especially advantageous during suboccipital keyhole surgery in the sitting position, which averts both cerebellar retraction and frequent soiling of the endoscope. In this case of a giant pineal papillary tumor in a 16-year-old patient, we used both a 3D-exoscope and a 45-degree angled endoscope complementarily (Video 1). The tumor underwent straight-ahead internal decompression using an exoscope. Once some space became available, the angled endoscope was inserted to excise the tumor initially in the inferior aspect and then rotated toward either side to dissect the tumor from the basal veins of Rosenthal. Lastly, the superior pole stuck to the undersurface of the vein of Galen was gradually excised. There were no neurologic deficits. Histopathology was a high-grade papillary tumor. Magnetic resonance imaging confirmed gross total resection. This is probably the first report of a supracerebellar infratentorial keyhole approach for gross total resection of a giant pineal tumor, effectively using the better ergonomics and depth of field of a 3D exoscope along with angled optics provided by an endoscope, resulting in an excellent outcome.
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