RESUMO
Endoscopic third ventriculostomy (ETV) is a well-established neurosurgical procedure. However, it carries risks of intraoperative complications, among which major vascular injury is the most dangerous. Reportedly, prominent bleeding during ETV has been noted in <1% of cases. Herein, we describe a case of a 34-year-old woman with occlusive hydrocephalus caused by a quadrigeminal cistern arachnoid cyst, who developed a pseudoaneurysm after injury of the basilar artery apex during ETV. Complete obliteration of the pseudoaneurysm with endovascular balloon-assisted coiling was done on the first postoperative day, and the patient demonstrated gradual recovery, but approximately 4 weeks later, she suffered massive rebleeding, seemingly due to rupture of the weak pseudoaneurysm wall, which resulted in her death. Careful evaluation of sagittal T2-weighted magnetic resonance images before ETV may be invaluable for assessment of the basilar artery position in relation to the third ventricle floor. In addition, use of a blunt surgical instrument (instead of a sharp one or cautery) for fenestration may be safer for prevention of arterial injury. Finally, special care should be applied in cases with an opaque third ventricle floor and inability to visualize the basilar artery during ETV.