Hydrocephalus after aneurysmal subarachnoid hemorrhage.

Hydrocephalus is a common and potentially devastating complication of aneurysmal subarachnoid hemorrhage (SAH). Its incidence is approximately 20% to 30%, and its onset can be acute, within 48 hours after SAH, or rarely chronic, occurring in a delayed fashion weeks and even months after the hemorrhage. Early recognition of its signs and symptoms and accurate interpretation of computed tomography (CT) studies are important for the management of patients with SAH. Clinically, a poor neurologic grade has the highest correlation with an increased incidence of hydrocephalus. Radiographically, the bicaudate index on CT studies has emerged as the best marker of this condition. Although further studies are needed to understand the complex pathophysiology of this condition, hydrocephalus after SAH can be treated effectively using current technology.