Ruptured intracranial aneurysm during pregnancy with false-negative computed tomography angiography findings: a case report.

A 34-year-old female was admitted at 34 weeks of gestation with sudden onset of a severe headache accompanied by vomiting. Neurological examination revealed neck rigidity, and computed tomography (CT) of the brain revealed a subarachnoid hemorrhage (SAH). Although the hemorrhage was located primarily in the left Sylvian fissure, computed tomography angiography (CTA) performed immediately after CT did not reveal any obvious vascular abnormalities such as an intracranial aneurysm. An emergency cesarean section was performed, and a healthy infant was delivered. Cerebral digital subtraction angiography (DSA) was performed the day following surgery, which revealed a saccular aneurysm measuring 4.3 mm × 2.4 mm in the left middle cerebral artery. Left craniotomy and clipping of the aneurysm were performed. The clot around the aneurysm was relatively solid. This case report is of significance given that initial CTA was negative for SAH during pregnancy, suggesting the requirement for immediate DSA or another CTA in such cases. There are many previous reports on false-negative CTA findings or disappearance and reappearance of aneurysms in SAH patients, and various biophysical and dynamic parameters are suggested to cause such phenomena. However, there are no reports on similar occurrences during pregnancy. Although the precise cause remains unclear, multiple factors associated with homeostasis during pregnancy were possibly associated with the transient disappearance in this patient.