Endoscopic third ventriculostomy, or ETV, is indicated for patients with obstructive hydrocephalus. The obstruction typically occurs around the tectum due to a tumor in the aqueduct or congenital aqueductal stenosis. It can also be considered in patients with development of subdural hematomas after shunting. An opening is created in the floor of the third ventricle and the membrane of Lilliequist1 using an endoscope placed in the ventricular system through a burr hole. This allows the cerebrospinal fluid to flow directly to the basal cisterns, bypassing any obstruction. Complications include hypothalamic injury, injury to the pituitary stalk or gland, transient cranial nerve III and VI palsies, injury to the basilar artery, posterior communicating artery, or posterior cerebral artery, uncontrollable bleeding, cardiac arrest, and traumatic basilar artery aneurysm. Overall success rate is about 56%. Pathologies such as tumor, previous shunting or subarachnoid hemorrhage, prior whole brain radiation, and adhesions decrease the success rate. The ETV Success Score is on a scale of 0-90% and is calculated based on age, etiology, and shunt history.


  1. Mortazavi MM, Rizq F, Harmon O, Adeeb N, Gorjian M, Hose N, Modammadirad E, Taghavi P, Rocque BG, Tubbs RS. Anatomical variations and neurosurgical significance of Liliequist's membrane. Childs Nerv Syst. 2015 Jan;31(1):15-28. doi: 10.1007/s00381-014-2590-5. Review. PMID: 25395307