抄録
Although computed tomographic angiography (CTA) is often the only modality for imaging before surgical treatment of intracranial aneurysms, it has some limitations and pitfalls. We report a case of diffuse subarachnoid hemorrhage (SAH) in which CTA revealed a small enhanced saccular abnormality on the surface of the caudal loop of the left posterior inferior cerebellar artery (PICA) that was highly suggestive of ruptured aneurysm. Surgical exploration failed to identify any PICA aneurysm but revealed an abnormal small structure with blood clot and a fibrous wall close by the PICA. The structure was connected to an irregularly shaped arteriole and easily bled, and was thus clipped with two hemoclips to prevent bleeding. Postoperative CTA scan demonstrated the hemoclips in precisely the same position as the enhanced abnormality on the preoperative image. We made a diagnosis of SAH caused by a distal PICA dissecting lesion with a false-positive saccular aneurysm on CTA and presumed that the contrast extravasation mimicked a distal PICA aneurysm. Physicians should be aware that the finding of a small aneurysm on CTA indicates a risk of a false-positive result, especially in patients being investigated for a ruptured aneurysm. Confirmatory imaging by repeated CTA or digital subtraction angiography is recommended in such cases.
