Diagnosis and Treatment of Cerebral Aneurysm Associated with Segmental Arterial Mediolysis: Our Experience and Systematic Review.

Background: Segmental arterial mediolysis (SAM) is a nonatherosclerotic, noninflammatory 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 previously reported cases and our cases.

Methods: We systematically searched cases of SAM-associated cerebral aneurysms using an online database. The findings of each included study and our cases were systematically reviewed in terms of characteristics, aneurysm, and clinical course.

Results: In addition to our 2 cases, 41 cases from 32 publications were included. SAM-associated cerebral aneurysms were common among East Asians, particularly Japanese, aged 40-50 years, and typically presented as subarachnoid hemorrhage (SAH; 86%). Most aneurysms (75%) were dissection aneurysms. Subarachnoid hemorrhage (SAH) cases had a higher risk of successive intra-abdominal hemorrhage (IAH) caused by visceral aneurysm rupture (59%), with a mortality of 41%. It was most likely to occur 8.2 ± 7.3 days after SAH. If operations were accomplished, the prognosis was relatively good (modified Rankin Scale score 0-3; 71%).

Conclusions: SAM-associated cerebral aneurysms can be life-threatening because of the risk of rupture and can lead to successive IAH after SAH. However, the prognosis is relatively good if an operation is successful. Therefore, precise diagnosis is required for suspected cases at first, and appropriate surgical treatment is required. Moreover, appropriate management of successive IAH is required among patients with SAH.