The Importance of Catheter Angiography in Computed Tomography Angiography-Negative Subarachnoid Hemorrhage

: Computed tomography angiography (CTA) has become an effective tool in the evaluation of patients with subarachnoid hemorrhage (SAH), but it still has limitations. Up to 15% of non-traumatic SAH cases are negative on CTA. The benefits of catheter angiography in the evaluation of certain cases of CTA-negative SAH have been previously demonstrated. Here, we present the case of a 48-year-old female who presented with headache and right-sided hemiparesis, who later became apneic and required intubation. A computed tomography (CT) scan of the head demonstrated a diffuse SAH. A CTA of the head and neck showed no vascular abnormality. Catheter angiography diagnosed a conical-shaped aneurysm at the left A1-A2 junction of the anterior communicating artery complex measuring 3.5 mm by 1 mm. The aneurysm was successfully treated with a craniotomy and microvascular clipping using a 4.7 mm curved Yasargil miniclip (Aesculap, Tuttlingen, Germany). This case illustrates the importance and benefit of catheter angiography in CTA-negative cases of SAH.