脳梗塞発症を契機に診断されたホモシスチン尿症の1成人例

A Case of Young Adult Presenting with Cerebral Infarction Caused by Homocystinuria

　要旨　21歳女性が左片麻痺，構音障害を主訴に来院した。頭部MRIで右半球に多発する新鮮梗塞が観察された。脳血管造影では右内頸動脈が起始部で完全閉塞していた。アミノ酸分析の結果，血中のメチオニン，ホモシステインの増加，尿中のホモシスチンの増加がみられホモシスチン尿症と診断した。本邦では，ホモシスチン尿症は1977年より行われている新生児マス・スクリーニングにより，発症前に治療が可能となり，典型的症状で発見されることはほとんどない。本例のごとく新生児期に発見されず，21歳になり脳梗塞で診断された例はきわめて稀である。若年性脳梗塞に遭遇した場合，ホモシスチン尿症の存在を考慮し，必要に応じてアミノ酸分析を行うべきである。

　Homocystinuria is a congenital metabolic disorder, and has been known as life-threatening risk factor of vascular disease including ischemic stroke. We report a case of cerebral infarction due to homocystinuria. The patient was a 21-year-old woman exhibiting left hemiparesis and a previous history of ectopia lentis. Magnetic resonance imaging showed multiple fresh infarctions in the right frontal and temporal lobes, basal ganglia, corona radiata, and internal capsule. The right common carotid angiogram demonstrated complete occlusion at the origin of the right internal carotid artery. Further investigation clarified increased level of serum methionine and homocysteine and urinary homocystin due to cystathionine beta-synthase deficiency. Homocystinuria was diagnosed as the cause of cerebral infarction. The patient was treated by low methionine diet and administration of folic acid, cobalamin, and aspirin. It should be recognized that some patients with homocystinuria are missed in the neonatal screening for congenital metabolic disorders. Recent studies indicated that the homocysteinemia is one of risk factors of ischemic stroke in the general population as well as in the patients of homocystinuria. We recommend metabolic screening for homocystinuria, when treating a juvenile patient with ischemic stroke of unknown etiology.

（Received : March 1, 2004）