Subarachnoid Hemorrhage Caused by Ruptured Distal Middle Cerebral Artery Aneurysm Mimicking Trauma-associated Onset after a Closed Head Injury: A Case Report

Abstract

A 52-year-old woman fell off her bike and sustained a head injury. In the emergency department, the patient was conscious but confused. Computed tomography (CT) revealed a subarachnoid hemorrhage (SAH) predominantly in the right Sylvian fissure. Fractures of the left temporal, clavicular, shoulder, and rib bones were also observed. Both CT angiography (CTA) and digital subtraction angiography (DSA) performed upon admission failed to identify the aneurysm. CTA performed 8 days later also failed to reveal the aneurysm. DSA performed 17 days after onset revealed a distal middle cerebral artery (d-MCA) aneurysm. Because of the traumatic event and the angiographically occult nature of the aneurysm up to 17 days after onset, it was difficult to determine whether it was a true aneurysm or a pseudoaneurysm. The patient underwent trapping and excision of the aneurysm, whereupon the pathological diagnosis was true aneurysm. The postoperative course was uneventful, and the patient was discharged 42 days after onset with no neurological deficits. Distinguishing between an aneurysmal SAH (a-SAH) and traumatic SAH (t-SAH) is difficult. In this study, we focused on identifying clinical differences between a-SAH and t-SAH and a surgical strategy for ruptured d-MCA aneurysms.