Subarachnoid hemorrhage due to nonbranching aneurysm of the middle cerebral artery in a young adult with a history of Kawasaki disease

BACKGROUND: The incidence of subarachnoid hemorrhage (SAH) in young adults is relatively rare. Kawasaki disease is a systemic vasculopathy that is known to cause coronary artery aneurysms; however, its effect on cerebral arteries remains largely unclear. CASE DESCRIPTION: We report the case of a 20-year-old male with a history of Kawasaki disease who presented with SAH caused by the rupture of a nonbranching middle cerebral artery aneurysm. This is the third report of SAH associated with Kawasaki disease. Preoperative echocardiography of the patient rejected the presence of bacterial endocarditis and other heart abnormalities. An emergency craniotomy and clip occlusion of the aneurysm was successfully performed without obstructing the parent artery. Two weeks later, the patient was discharged without any apparent neurological deficit. We also performed a circumstantial pathological study on specimens obtained from the aneurysm wall. Our histological findings suggest that the elastic lamina and tunica intima were completely destroyed during the acute vasculitis phase of Kawasaki disease, which possibly led to the aneurysmal formation. CONCLUSIONS: Lack of active inflammatory changes and atherosclerotic lesions may explain the chronic feature of Kawasaki disease, not a typical aneurysmal formation.