Figure 1

Axial (A), coronal (B) and sagittal (C) computed tomography angiography scans showing a dilated precommunicating segment of the right anterior cerebral artery. An angiogram of the right internal carotid artery (D) showing a false lumen at the level of the precommunicating segment of the right anterior cerebral artery suspected to be a dissecting aneurysm. An angiogram of the left internal carotid artery (E) demonstrating that both right and left postcommunicating segments of the anterior cerebral artery are perfused from the left anterior cerebral artery. An angiogram of the right internal carotid artery (F) showing the impossibility of accessing the aneurysm via an endovascular route due to its characteristic features and the vasospasm.