Literature Reviews Diagnosis and treatment of cerebral aneurysm associated with segmental arterial mediolysis: our experiences and systematic review

Segmental arterial mediolysis (SAM) is a non-atherosclerotic, non-inflammatory vascular disease, initially reported in 1976 by Slavin and Gonzalez-Vitale. SAM-associated cerebral aneurysms have been reported in limited cases, and the disease entity is not fully understood. Therefore, we propose a diagnostic and treatment strategy with a systematic review of previous reported cases and our cases. We systematically searched cases on SAM-associated cerebral aneurysms using an online database. Findings of each included study and our cases were systematically reviewed in terms of characteristics, aneurysm, and clinical course. In addition to our two cases, a total of 41 cases from 32 publications were included. SAM-associated cerebral aneurysms were common among East Asian, particularly Japanese, aged 40-50 years, and typically presented as subarachnoid hemorrhage (SAH, 86%). Most (75%) aneurysms were dissection aneurysms. Notably, subarachnoid hemorrhage (SAH) cases had a higher risk of successive intra-abdominal hemorrhage (IAH) due to visceral aneurysm rupture (59%), with a mortality rate of 41%. It was most likely to occur on 8.2±7.3 days after SAH. If operations were accomplished, prognosis was relatively good (modified Rankin Scale 0-3: 71%). SAM-associated cerebral aneurysms can be life-threatening due to the risk of rupture, and can lead to successive IAH following SAH. However, prognosis is relatively good if operation is accomplished. Therefore, precise diagnosis is required for suspected cases at first, and appropriate surgical treatment is required. Moreover, appropriate management on the alert of successive IAH is required among SAH cases.