内頸動脈解離による脳梗塞発症31病日にくも膜下出血を起こしたde novo aneurysmの1例  [in Japanese] A Case of Cervical Internal Carotid Artery Dissection-induced Cerebral Infarction Followed by Subarachnoid Hemorrhage with de novo Aneurysm on Day 31  [in Japanese]

We report the case of 41-year-old woman with a de novo aneurysm originating at the antero-lateral wall of the contralateral internal carotid artery (ICA) 31 days after the cerebral infarction due to the dissection of the ipsilateral cervical ICA. She developed right hemiparesis and aphasia. Head CT showed fresh cerebral infarction in the left ICA territory, and head MRA showed a stenosis in the left cervical ICA. Carotid ultrasonography indicated an intramural hematoma at the origin of the left ICA, and staccato flow was observed on the Doppler examination, suggesting the dissection of the ICA. Although neuroprotective and anticoagulant therapies were carried out, she developed a sudden severe headache and generalized convulsion on Day 31 since cerebral infarction. Head CT revealed subarachnoid hemorrhage, and a following 3D-CT angiogram showed a saccular de novo aneurysm at the anterolateral and non-branching wall of the supraclinoid ICA on the right. We performed right fronto-temporal craniotomy and neck clipping of the aneurysm. Since no aneurysms had been observed at the affected site on the initial MRA, which was conducted at the onset of cerebral infarction, it was surmised that a de novo aneurysm developed over a short period of time as a result of the hemodynamic stress after the occlusion of the left ICA. This case study may be of importance for clarifying the pathogenesis of aneurysms.