[Delayed Hydrocephalus Following Embolization with Hydrogel Coils for an Unruptured Aneurysm at the Tip of the Basilar Artery:A Case Report].

We report the case of a 62-year-old woman with delayed hydrocephalus following endovascular embolization with hydrogel coils for an unruptured aneurysm at the tip of the basilar artery. She underwent the first and second embolizations with bare platinum coils and matrix coils, respectively. However, recanalization and regrowth of the aneurysm was observed, and a successful third embolization with hydrogel coils(2 mm/4 cm×2)was performed. However, progressive ventricular enlargement was observed during 8 months after the third treatment. MRI with fluid-attenuated inversion recovery sequence showed edema in the perianeurysmal white matter, as well as marked communicating hydrocephalus. The aneurysmal wall was enhanced with the administration of gadolinium-DTPA. The cerebrospinal fluid(CSF)protein level was 113 mg/dL. A ventriculo-peritoneal shunt was placed, and the patient was discharged without symptoms. It was postulated that endovascular embolization with hydrogel coils causes inflammation of the aneurysmal wall and perianeurysmal white matter, followed by elevation of CSF protein and subsequent communicating hydrocephalus.