Department of Neurology, Showa University Fujigaoka Hospital, Yokohama, Japan;
Department of Neurology, Machida-Keisen Hospital, Machida, Japan;
Department of Neurosurgery, Showa University Fujigaoka Hospital, Yokohama, Japan;
Cryptogenic; Brain; Abscess; Patent; Foramen; Ovale; Posterior; Circulation; Area; Aging;