亜急性硬膜下血腫—自験例4症例と文献的報告

SUBACUTE SUBDURAL HEMATOMA : REPORT OF 4 CASES AND A REVIEW OF THE LITERATURE

　硬膜下血腫は，急性と慢性に大別され，その病態は全く異なるが，著者らは，両方の特徴が混在した亜急性硬膜下血腫の4症例を経験した。それらの特徴は，1）高齢者であること。2）外傷歴不明か，軽微な外傷後に発症すること。3）アルコール多飲歴，高血圧症，糖尿病など，high riskを有すること。4）頭部CT上，mixed density hematomaを呈すること。5）術中所見として，皮質動脈からの出血を認めることがあり，完成した血腫被膜は存在しないこと。6）転帰は合併症のため，不良となることもあること。などであった。以上のように，臨床経過およびCT所見は，慢性硬膜下血腫に類似しているが，その手術所見は，急性硬膜下血腫であり，術前診断は難しかった。亜急性硬膜下血腫の成立機転は，止血凝固異常，脳萎縮に関連した反復する小出血と考えられ，MRIにおけるmixed signal intensity所見は，診断上重要と思われた。また治療にあたっては，穿頭術では血腫残存の可能性が高く，大開頭による止血および血腫除去が必要と思われた。

Subdural hematoma is divided roughly into two types acute and chronic. The two show an entirely different mode of illness. The authors have en-countered 4 cases of subacute subdural hematoma in which characteristics of both types coexisted. These cases are characterized by the following. 1) The disease develops in the elderly persons with a history of trauma unknown or after minorhead injury. 2) There is a relatively long period of clear consciousness and they visit a hospital when they are in the subacute stage, 3) They have a history of drinking alcohol heavily as a habit and there is a high risk of hypertension and diabetes. 4) Brain CT finding sometimes reveals mixed density hematoma. 5) Hemorrhage from the cortical artery is occasionally noted as the oper-ative findings. Hematoma membrane is absent. 6) The outcome is generally pcor because of sys-temic complications.

As described above subacute subdural hematoma was similar to chronic subdural hematoma in the clinical course and CT findings. But operative findings of this disease indicated acute subdural hematoma. Repeated minor hemorrhage, related to coagulation disorder and brain atrophy would be important as the mechanism of subacute sub-dural hematoma. The effectiveness of perforation craniotomy as radical operation was low and removal of hematoma by major craniotomy was needed. The concept of subacute subdural hema-toma is considered important in deciding on a therapeutic policy.