Dissecting Aneurysms at the A1 Segment of the Anterior Cerebral Artery. Two Case Reports.

Abstract

Two rare cases of dissections which involve the anterior cerebral artery (ACA) are reported. A 58-yearold woman presented with a ruptured dissecting aneurysm manifesting as sudden onset of severe headache and consciousness disturbance followed by aphasia, right hemiparesis, paresis of the left lower extremity, and choreoathetotic movements of the upper arms and face. Computed tomography and angiography revealed subarachnoid hemorrhage due to a dissecting aneurysm at the left A 1 segment. The dissecting aneurysm was trapped surgically on the day of onset. Her neurological deficits disappeared within a month. A 39-year-old woman experienced continuous dull headache from the day before onset, and then suffered right hemiparesis. Magnetic resonance (MR) imaging revealed cerebral infarction at the left globus pallidus. Angiography and MR imaging revealed a dissecting aneurysm at the left A 1 segment and occlusion of the left Heubner's artery. She received conservative treatment and her neurological findings were improved. Dissections or dissecting aneurysms involving the ACA can be classified into three types: Extension of a dissection to the ACA from the internal carotid artery, dissection at the A 1 segment, and dissection at the A 2 -A 4 segments. These types of dissection have distinct uniform clinical features.

Isolated Anterior Cerebral Artery Territory Infarction: Dissection as an Etiological Mechanism

“…To begin with, intracranial arterial lesions are more common in Asian patients than in non-Asian patients [19,20,21]. With respect to ACA dissection causing brain ischemia, the case reports that were published were almost exclusively from Japan [8,22,23,24,25,26,27,28,29]. However, another explanation for the difference may be that ACA dissection may not have been diligently sought and may have been underdiagnosed in the previous studies [1,2,3,4,5].…”

“…However, since the ACA is narrow and curved, small dissections may be hard to accurately diagnose. Advances in high quality diagnostic imaging techniques, such as MRA and 3D-RA, may provide a basis for accurate diagnosis of the dissection [8,22,23,24,25,26,27,28,29]. In particular, 3D-RA provides precise depiction of the intracranial vasculature, including aneurysms [30].…”

“…Of 10 patients who presented with ischemic stroke from case reports of ACA dissection, physical exertion was noted in 2 patients, headache was noted in 8, and sudden onset of stroke symptoms was described in 5 [22,23,24,25,26,27,28,29]. Such conditions seem to provide useful clues to the diagnosis of dissection.…”

3D-Rotational Angiographic Demonstration of Dissection of the Anterior Cerebral Artery

“…Although the double lumen sign, which is visible fl ow in both the true and false lumen [6] , has been suggested to be a pathognomonic, it is rarely seen in intracranial arteries [1] . To the best of our knowledge, only 4 cases of the double lumen sign in the ACA have been reported in the English literature [7][8][9] . Kazui et al [10] reported 17 patients with solitary infarction in the territory of the ACA, including 4 of undetermined etiology.…”

Subarachnoid Hemorrhage from Spontaneous Dissection of the Anterior Cerebral Artery

“…If there is a high risk of rebleeding (rebleeding under conservative treatment, growing dissecting aneurysm, giant dissecting aneurysm, traumatic dissecting aneurysm or dissection associated with uncontrolled hypertension), direct treatment of the dissection might be proposed. Several surgical techniques have been attempted such as wrapping [16,21,22,25] , trapping with [3] or without [6,8,11,17,19,20,23,26] bypass surgery or clipping of the aneurysmal bulge [11,16] . The endovascular treatment consists in proximal occlusion, obstruction of the aneurysmal bulge or stent placement [13] .…”