Application of Endoscopic Underwater Surgery for Brain Tumors from Ventricle to Cistern: A Report of Pediatric and Elderly Cases.

Postoperative brain collapse and subdural fluid collection are potential complications after craniotomy in pediatric and geriatric neurosurgery. We have been using underwater surgery for intraventricular tumors in pediatric patients since 2011 and have recently expanded its use for extra-axial brain tumors in older adult patients. Herein, we introduce our underwater surgical technique and present 3 cases: the first application of underwater surgery for a pediatric intraventricular tumor, and 2 recent cases of cisternal tumors in older adults treated with this technique. We have only used underwater surgery for non-highly-vascularized extra-axial tumors located in the ventricle or cistern, which are considered amenable to hemostasis in the underwater surgical setting. During underwater surgery, the patient is positioned such that the craniotomy site is at the highest position. The craniotomy is limited to 3 cm, and the surgical field is irrigated with artificial cerebrospinal fluid during intradural surgery. In the cases of patients with extra-axial tumors reported herein, underwater surgery was successfully performed without postoperative complications such as subdural fluid collection. Consequently, this surgical method shows promise for preventing postoperative cerebral subsidence and subdural fluid collection in both pediatric and geriatric patients, although its application is contraindicated for large and hemorrhagic tumors.