Aneurysms of the vein of Galen are uncommon vascular malformations. They are most frequently seen in infants and children, leading to heart failure and hydrocephalus. Exceptionally, they are detected in adults. Several theories have been proposed to explain hydrocephalus in these patients: obstruction of the cerebral aqueduct, impaired absorption of CSF after subarachnoid hemorrhage, passive ex-vacuo mechanism, or thrombosis of an aneurysm. Hydrocephalus has been treated mainly with cerebrospinal shunt procedures, but also direct surgery, radiosurgery and embolisation of the malformation have proved to be effective. We report the case of a partially thrombosed ectasia of the vein of Galen in a 44-year-old male, with huge hydrocephalus successfully treated with an endoscopic third ventriculostomy
