脳動脈瘤の新生および増大を観察し得た1症例

Observation of De Novo Formation and Growth of an Intracranial Aneurysm: A Case Report

Ⅰ．はじめに

　以前の画像で認められなかった脳動脈瘤が新たに発見された場合，新生脳動脈瘤という．近年，いくつかの新生脳動脈瘤のシリーズの報告がある^10,13,15,23)が，そのほとんどは，くも膜下出血から平均10年前後に破裂して診断されている．一方，1回目のくも膜下出血から2年以内の短期間に新生，破裂して発見された症例報告も散見される^{1,5,11,16,17,24)}．しかし，くも膜下出血後に定期的に画像検査を行い，脳動脈瘤の新生および増大を観察した報告はこれまでにない．われわれは家族歴のある若年女性の右内頚動脈瘤破裂によるくも膜下出血手術後に，残存した未破裂左中大脳動脈瘤を6カ月ごとに画像で観察したところ，6年後に右前大脳動脈遠位部に新生して増大した動脈瘤の1手術例を経験したので報告する．

　We observed a de novo formation and growth of an aneurysm in a 43-year-old woman who was followed up after treatment of a subarachnoid hemorrhage (SAH).

　In 2002, the patient, whose mother had a history of SAH, presented with SAH at the age of 36. Three-dimensional computed tomography angiography (3D-CTA) and digital subtraction angiography showed an aneurysm in the right internal carotid-posterior communicating artery. The aneurysm was clipped and postoperative course was uneventful without neurological deficit.

　The patient was followed up by 3D-CTA and magnetic resonance angiography every 6 months, because of an untreated small aneurysm, 3 mm in diameter, in the left middle cerebral artery (MCA). The MCA aneurysm remained unchanged but a de novo aneurysm, 1.5 mm in diameter, developed in the right anterior cerebral artery (ACA) 6 years after the first surgery. The ACA aneurysm grew to 4 mm in diameter during the following 10 months but the MCA aneurysm remained unchanged. Both aneurysms were clipped in one session. The MCA aneurysm had a smooth wall but the ACA aneurysm had an irregular and thin wall. The postoperative course was uneventful.

　Young female patients who have developed SAH with familial history,like this case,should receive long-term follow up to check whether a de novo aneurysm has developed.