Early Development of Intimal Thickening in Superficial Temporal Arteries in Patients With Moyamoya Disease

Background and Purpose Moyamoya disease is a progressive cerebrovascular occlusive disease that occurs in children. The etiology is unknown. We examined the superficial temporal arteries from patients with moyamoya disease, particularly children, to determine whether the extracranial arteries as well as the intracranial arteries are involved in this disease. Methods Small branches of the superficial temporal arteries were obtained from 22 patients with moyamoya disease during indirect arterial bypass surgery. Histological examinations were performed, and the findings were compared with those of arteries from 12 control patients. Results Intimal thickening was observed in 9 of 17 patients with moyamoya disease younger than 20 years but in none of 7 control patients under the age of 20 years ( P <.02, Fisher's exact test). Intimal thickening appeared from age 20 years in control patients. The arteries of moyamoya patients showed fibrocellular intimal thickening with a paucity of lipid. The arteries from moyamoya patients contained strongly stained multilayered elastic fibers in the thickened intima, while those from control patients showed only weakly stained elastic fibers in the intima. Conclusions Our findings suggest that moyamoya disease is a systemic vascular disease. The results indicate systemic etiologic factors that may promote the early development of intimal thickening in moyamoya disease.