Delayed Hydrocephalus and Perianeurysmal Cyst Formation After Stent-Assisted Coil Embolization of a Large, Unruptured Basilar Apex Aneurysm: A Case Report and Literature Review

Purpose: Endovascular aneurysm embolization possesses a unique set of infrequently seen complications distinct from those associated with microsurgical clipping, which may arise after an otherwise uncomplicated coil embolization procedure, including postembolization, hydrocephalus, and perianeurysmal cyst formation. Design: The authors report an illustrative case of 2 rarely seen complications of aneurysm embolization with literature review. Methods: We present a case of a basilar apex aneurysm that was treated with endovascular coil embolization with multiple Cerecyte (Micrus Endovascular, San Jose, Calif) coils and 2 Enterprise (Codman & Shurtleff, Inc, Raynham, Mass) stents. Results: Postembolization angiography demonstrated complete aneurysm obliteration without distal branch occlusion or other complication. Twenty-two months after the embolization, however, the patient presented with progressively worsening headaches. Repeat magnetic resonance imaging revealed hydrocephalus and a perianeurysmal cyst measuring 1 × 2 cm adjacent to the previously coiled basilar apex aneurysm. After endoscopic third ventriculostomy, the patient experienced significant relief of her headaches and was discharged to rehabilitation. Conclusions: Clinicians should be aware that worsening or new neuro-ophthalmic findings may be the presenting sign of postembolization hydrocephalus or perianeurysmal cyst formation.