Delayed Posterior Choroidal Artery Aneurysm Formation and Rupture in a Postsuperior Temporal Artery to Middle Cerebral Artery Bypass Moyamoya Disease Patient

Abstract

Background Moyamoya disease is a rare vascular disease that presents with stenosis of the internal carotid artery accompanied by formation of abnormal, fragile blood vessels at the base of the brain. This pathology often presents with aneurysms, which may cause ischemic or hemorrhagic complications. We present a case of posterior choroidal artery aneurysm in a moyamoya disease patient that ruptured following a 6-year asymptomatic period after the patient received superior temporal artery to middle cerebral artery bypass.

Observations A 57-year-old female Japanese patient who received superficial temporal artery to middle cerebral artery bypass for moyamoya disease presented to the Nippon Medical School Hospital emergency room for sudden loss of consciousness after a 6-year asymptomatic period following her bypass procedure. She was diagnosed with left subcortical hemorrhage with ventricular rupture and hydrocephalus associated with a left medial posterior choroidal artery aneurysm. This was then subsequently managed with bilateral ventricular drainage, clipping, spinal drainage, and finally lumbar–peritoneal shunt.

Conclusion Our case demonstrates delayed aneurysm formation at the posterior choroidal artery even after bypass surgery. Our patient’s 6-year silent period after her bypass surgery highlights the need for long-term surveillance after the immediate postoperative period even if the patient is asymptomatic due to the possibility of chronic cerebrovascular changes following bypass that may go undetected.