抄録
Nontraumatic or “spontaneous” acute subdural hematoma (SDH) is rare, and “pure” acute SDH without subarachnoid hemorrhage (SAH) due to aneurysmal rupture is extremely rare. We report a case of nontraumatic pure acute SDH caused by the rupture of a cortical middle cerebral artery (MCA) aneurysm. A 43-year-old man with no antecedents, except hypertension, presented to the emergency department with acute-onset moderate headache and nausea after swimming. He reported neither preceding head trauma nor dental check-up. Neurological examinations and laboratory tests were unremarkable. Computed tomography (CT) showed an acute SDH on the left convexity without SAH, but both magnetic resonance (MR) angiography and three-dimensional CT (3D-CT) angiography disclosed no vascular abnormality. As he became drowsy, the patient emergently underwent an evacuation of the SDH. Unexpectedly, a small saccular aneurysm of a cortical branch of the left MCA was recognized at surgery. Although indocyanine green (ICG) angiography revealed this aneurysm was thrombosed, a clip was applied on the aneurysmal base. He was discharged home without any complications 21 days after admission. To seek the cause of nontraumatic acute SDH, supplementary examinations including 3D-CT, MR, and/or catheter angiography are necessary. Even if angiography reveals no vascular lesions, the present case warrants that the cortical surface should be meticulously inspected at surgery, because a thrombosed cortical artery aneurysm might be an underlying cause.
