Unusual delayed hydrocephalus after bare platinum coil embolization of an unruptured aneurysm

A 69-year-old woman developed hydrocephalus after the embolization of an incidentally detected unruptured large internal carotid artery aneurysm with bare platinum coils. Endovascular embolization resulted in near-total aneurysm occlusion. She complained of mild headache 18 hours after the procedure and magnetic resonance (MR) imaging performed on the 6(th) post-treatment day revealed wall enhancement and perianeurysmal brain edema. Follow-up MR imaging showed recanalization of the aneurysm and gradual ventricular enlargement. She presented with typical symptoms of hydrocephalus including disorientation, gait disturbance, and urine incontinence at 7 months post-embolization. We removed 30 ml of cerebrospinal fluid by lumbar tap, which improved her condition without symptom recurrence for 2 months. She did not require shunt placement. Post-interventional hydrocephalus is known in patients with unruptured aneurysms embolized with bioactive second-generation coils. This case shows that hydrocephalus can occur after aneurysm embolization with bare platinum coils without intracranial hemorrhage.