A Case of Segmental Arterial Mediolysis: Hemoperitoneum with Hemorrhagic Shock due to Rupture of a Visceral Artery Aneurysm Following Subarachnoid Hemorrhage.

Objective: Segmental arterial mediolysis (SAM) is a non-inflammatory and non-atherosclerotic vascular disease characterized by segmental medial defect/necrosis of muscular arteries as a result of mediolysis. SAM affects the visceral and intracranial arteries, and causes arterial dissection and aneurysm. We report a case of aneurysmal subarachnoid hemorrhage (SAH) followed by hemoperitoneum due to a ruptured visceral artery aneurysm. Case Presentation: A 54-year-old man developed SAH from a ruptured anterior communicating artery aneurysm, which was clipped on the same day. Thereafter, he was treated to prevent cerebral vasospasm. Six days after onset, he developed acute anemia and his blood pressure decreased, suggesting hemorrhagic shock. Hemoperitoneum was detected on computed tomography and abdominal angiography was performed. Irregular and stenotic arterial findings, and an unusual aneurysm with contrast stasis were found in a branch vessel from the right gastroepiploic artery. SAM was diagnosed based on the clinical course and angiographic characteristics. Endovascular treatment consisted of embolization of the visceral artery aneurysm with liquid embolic material. after embolization, the vital signs stabilized and he recovered from shock. Acute treatment for SAH was continued. Although the patient did not develop vasospasm-related sequelae, he was transferred to the rehabilitation hospital 7 weeks after onset and his modified Rankin Scale score at 3 months after onset was 2. Conclusion: Visceral artery aneurysm associated with SAM should be considered as the cause of hemoperitoneum with hemorrhagic shock during the acute phase of SAH.