Rupture Risk Factors and Strategies for Unruptured Distal Anterior Cerebral Artery Aneurysms.

BACKGROUND: Distal anterior cerebral artery (dACA) aneurysms are rare. Ruptured dACA aneurysms typically present with subarachnoid hemorrhage in conjunction with intracerebral hematoma and cause neurological deterioration. This study aimed to determine their risk of rupture and examine associated factors. METHODS: We retrospectively analyzed patients with dACA aneurysms to compare patient and aneurysm characteristics between ruptured and unruptured aneurysms. Clinical outcome was used the modified Rankin scale. Univariate analyses were performed to identify rupture risk factors. RESULTS: One hundred three patients with dACA aneurysms were examined (51 ruptured and 52 unruptured). The median aspect ratio of ruptured and unruptured aneurysms was 1.69 and 1.22, respectively (P < 0.01). The median maximum diameter of ruptured and unruptured aneurysms was 5.2 and 3.1 mm, respectively (P < 0.01). The median size ratio of ruptured and unruptured aneurysms was 3.32 and 2.17, respectively (P < 0.01). Maximum diameter was <5 mm in 45.2% of ruptured dACA aneurysms. dACA aneurysm, showing size ratio >2.4 and aspect ratio >1.4, had ruptured in 71.4% and 78.6%, respectively. We suggested that these are the threshold of size ratio and aspect ratio for rupture of dACA aneurysms. A total percentatge of 78.1% of aneurysms with aspect ratio >1.4 and size ratio >2.4 had ruptured. CONCLUSIONS: Distal anterior cerebral artery (dACA) aneurysms may rupture, even when small. We found a significant difference between ruptured and unruptured aneurysms with respect to maximum diameter, aspect ratio, and size ratio. Treatment for small aneurysms should be considered based on size ratio and aspect ratio, not just size.

Ruptured Distal Middle Cerebral Artery Aneurysms-Characteristics and Strategy.

BACKGROUND: Distal middle cerebral artery (dMCA) aneurysms are very rare. Most ruptured dMCA aneurysms lead to subarachnoid hemorrhage (SAH) coexisting with intracerebral hematoma (ICH), resulting in a deteriorating state. The risk factors of rupture of dMCA aneurysms remain unknown. To elucidate the risk of rupture, we studied differences between 4 ruptured and eleven unruptured dMCA aneurysms. METHODS: We retrospectively analyzed patients diagnosed with a dMCA aneurysm according to the maximum size of the aneurysm, aspect ratio, and aneurysm size to vessel size (size ratio). RESULTS: Four patients presented with SAH coexisting with ICH, resulting in a midline shift, caused by rupture of the dMCA aneurysm. The median aspect ratio of ruptured and unruptured dMCA aneurysms was 2.38 and 1.65, respectively, with no significant difference. The median maximum diameter of ruptured and unruptured dMCA aneurysms was 2.98 and 3.78 mm, respectively, with nonsignificant difference. The median size ratio of ruptured and unruptured dMCA aneurysms was 3.13 and 1.84, respectively, being significant difference (P < 0.02). The outcomes of 4 patients having ruptured dMCA aneurysm were as follows: one patient died due to the initial attack, and the others were severely disabled due to cerebral infarction caused by vasospasm. CONCLUSIONS: Distal MCA aneurysms, even if they are small, may be likely to rupture leading to SAH complicated by ICH and result in a poor neurological state and unfavorable outcomes. We recommend aggressive treatment for dMCA aneurysms considering morphological factors such as the size ratio even if they are small and unruptured.

A Case of Intracranial Vertebral Artery Dissection Undetected by CT, MRI, and MRA at the Onset of Headache That Caused Subarachnoid Hemorrhage Seven Days Later.

Objective: We report a patient with normal imaging findings at the onset of preceding headache who developed subarachnoid hemorrhage (SAH) due to intracranial vertebral artery dissection 7 days later. Case Presentation: A 51-year-old woman with a history of chronic headache visited our emergency outpatient department with a complaint of mild to moderate right nuchal pain. CT, MRA, and MRI (diffusion-weighted image, T2-weighted image, FLAIR, MR cisternography, and basi-parallel anatomical scanning) were normal. Seven days later, she was admitted to our hospital with sudden disturbance of consciousness. CT revealed SAH and CTA demonstrated dilatation of the right vertebral artery (VA). The dilated lesion with an intimal flap on the right VA proximal to the posterior inferior cerebellar artery was confirmed on DSA. The dilated lesion and the proximal VA were occluded endovascularly using coils. The condition of the patient improved gradually, and she was transferred to the rehabilitation hospital on day 45 with a modified Rankin Scale score of 2. Conclusion: The clinical course of the presented case, although rare, should be kept in mind in daily clinical practice.

Non-Sinus-Type Laterocavernous Sinus Dural Arteriovenous Fistula Treated by Transarterial Venous Coil Embolization: A Case Report.

Objective: Laterocavernous sinus dural arteriovenous fistulas (DAVFs) are rare and not always accessible transvenously due to their angioarchitecture. We report a case of non-sinus-type laterocavernous sinus DAVF treated by endovascular transarterial venous coil embolization. Case Presentation: A 78-year-old woman was admitted to our hospital with loss of consciousness, right hemiparesis, and motor aphasia. CT demonstrated intracerebral hematoma in the left frontal lobe and subarachnoid hemorrhage. On CTA and MRA, a DAVF was found in the left laterocavernous sinus region associated with the accessory meningeal artery (AMA) and draining directly into the superficial middle cerebral vein. The diagnosis was confirmed by DSA, which revealed a DAVF fed by the large and straight AMA and the internal carotid artery's meningohypophyseal trunk. Endovascular transarterial venous coil embolization was performed through the AMA. A microcatheter was advanced beyond the shunt point into the origin of the draining vein, and coils were placed in the venous and arterial sides of the fistula. The fistula was completely occluded, and 15-month follow-up angiography demonstrated stable obliteration of the fistula. Conclusion: Transarterial venous coil embolization may be a treatment option for non-sinus-type laterocavernous sinus DAVF with a large fistula size and a large and straight feeding artery.