There are three major complications after a ruptured cerebral aneurysm: re-rupture, cerebral vasospasm, and hydrocephalus. Let’s talk about hydrocephalus today. First we classify hydrocephalus due to subarachnoid hemorrhage: by time: acute hydrocephalus (within 2 weeks) and chronic hydrocephalus (>2 weeks) by site of obstruction: obstructive hydrocephalus and communicating hydrocephalus What is the incidence of hydrocephalus due to subarachnoid hemorrhage? The bulk of cases summarized as acute hydrocephalus is 20%, 2/3 of acute hydrocephalus bleeding clinical symptoms, half of them can recover on their own. 10-20% of surviving patients develop chronic hydrocephalus. Why does hydrocephalus occur after subarachnoid hemorrhage? Blockage by blood clots is the result of obstruction of the interventricular foramen, aqueduct and fourth ventricular outlet, accumulation of blood in the brain pool, and obstruction of the arachnoid granules (or villi) by blood and degraded components leading to impaired cerebrospinal fluid circulation or absorption. How to deal with hydrocephalus after subarachnoid hemorrhage? 1, close observation if there is impaired consciousness should be performed extraventricular drainage. 2. Ventricular drainage after ventricular hemorrhage is not correlated with re-rupture of the aneurysm. 3.For patients with impaired consciousness caused by hydrocephalus, the author tried to perform extraventricular drainage and cerebral aneurysm clamping at the same time with satisfactory results. 4, chronic hydrocephalus should be performed ventriculoperitoneal shunt.