術後過灌流が再燃して症候化したと考えられる成人もやもや病の1例

Recurrent Hyperperfusion after Revascularization Surgery for Adult Moyamoya Disease: A Case Report

Ⅰ．はじめに

　もやもや病は，内頚動脈終末部の狭窄や閉塞とウィリス動脈輪周囲で形成される異常な血管網を特徴とする疾患である^6,8)．虚血発症のもやもや病に対する外科治療は浅側頭動脈-中大脳動脈（superficial temporal artery to middle cerebral artery：STA-MCA）バイパスに代表される直接血行再建術と，encephalo-duro-myo-arterio-pericranial synangiosis（EDMAPS）などの間接血行再建術に分けられる⁷⁾．間接血行再建術は，側副血行路が構築されるまでに時間を要するのに対して，直接血行再建術は，脳循環代謝をただちに改善することができる．その一方で，近年，もやもや病に対する直接血行再建術の後に過灌流現象（hyperperfusion）が発生し得ることもわかってきた．この現象は場合によっては痙攣や脳出血などの重大な合併症につながり得るため注意が必要である．過去の報告では，過灌流現象は直接血行再建術後の1週間以内に発生し，長い場合は約2週間程度継続するとされている^5,9)．今回，われわれは，術後2日目にいったんは改善した過灌流現象がその後に再燃し，症候化して脳出血を来した稀な1例を経験したので報告する．

　Direct bypass surgery for moyamoya disease is quite useful for rapidly improving cerebral hemodynamics and resolving ischemic attacks but may induce hyperperfusion syndrome. In this report, we present a rare case of recurrent hyperperfusion after surgery for moyamoya disease. A 47-year-old woman developed left homonymous hemianopsia and was admitted to our hospital. Magnetic resonance（MR）imaging/angiography revealed definitive moyamoya disease presenting with acute cerebral infarction in the right temporoparietal lobe. She was treated with anti-hypertensive agents because she had severe hypertension. She successfully underwent right superficial temporal artery-middle cerebral artery double anastomosis and indirect bypass. A cerebral blood flow study just after surgery demonstrated marked hyperperfusion in the operated hemisphere. A repeat study 2 days later revealed that the hyperperfusion was dramatically improved. Subsequently, however, she developed a severe ipsilateral headache and focal seizure regardless of the blood pressure control. She complained of the headache for ＞2 weeks. Follow-up MRI showed a small subcortical hemorrhage in the right frontal lobe. Single-photon emission computed tomography revealed that the hyperperfusion relapsed 9 days after surgery and then gradually disappeared. This study shows that preoperative severe hypertension may induce uncontrollable hyperperfusion after direct bypass surgery for moyamoya disease.