被膜形成を伴う血腫へ進展する急性硬膜下血腫の検討

A Study of Acute Subdural Hematoma Developing into Hematoma with Capsule Formation

I．はじめに

　急性硬膜下血腫（ASDH）からいわゆる慢性硬膜下血腫様の血腫への進展例の存在は一般に認識されてはいるが^7,8,13），臨床上これを経験することは少なく，文献的にも数件の報告が渉猟できるのみである^{6,16-18,23）}．その正確な頻度は不明であるが，ASDH保存的治療群に限定しても本経過は9-10％に過ぎない^3,17）．そのため，本病態の検討が十分になされたとは言えず，特に，どのようなASDH例が本経過をとるのか，また，本経過で進展形成された血腫を慢性硬膜下血腫とする診断は妥当なのか等の疑問は未だ解決されていない．

　今回，われわれは過去13年間に集積した10症例から，本経過例の特徴点につき検討したところ，本病態に関する若干の知見の集積をみたので報告する．

There are some cases in which conservatively treated acute subdural hematoma (ASDH) does not dis-appear naturally and progresses to chronic subdural hematoma-like hematoma (CSDH) (hematoma withcapsule formation). The objective of the present study was to identify factors which can be used to predictthis unfavorable course during the early phase after the onset of the lesion. During the past 13 years, 10 of96 cases of mild, conservatively treated ASDH (excluding suckling infants) progressed to CSDH, andthose 10 patients showed the following background characteristics. There were 7 males and 3 females, andthe mean age was 63.1 years. Five of the patients had a history of alcohol consumption, and one case eachhad a history of cerebral infarction, cerebral hemorrhage and a VP shunt. Acute-phase computerizedtomography (CT) at the time of ASDH showed, in all 10 cases, an expansive-type lesion with a low densi-ty area in the hematoma, with expansion of the hematoma into the interhemispheric fissure. The hema-toma was observed to undergo transient natural shrinkage in the acute phase. The period for progressionto CSDH was indicated to be a mean of 20.5 days after the onset of the lesion, and its cure was possiblewith trepanation. In consideration of these results, it was surmised that ASDH patients with the followingcharacteristics have a high risk of progression to CSDH during the subacute and chronic phases when con-servative therapy is administered during the acute phase of the lesion: (1) old age, (2) a history indicativeof brain atrophy, (3) an expansive-type image of ASDH on acute-phase CT, and (4) acute-phase CT in-dicative of cerebrospinal fluid mixing in the hematoma.