特発性脳内血腫

SPONTANEOUS INTRACEREBRAL HEMATOMA

緒言

　脳内血腫の原因としては，外傷，脳動脈瘤あるいは脳動静脈奇形の破裂，高血圧性脳出血などが主なものであるが，脳内血腫あるいは脳内出血を分類する場合には，外傷性と特発性（spontaneous）または1次性（primary）に分ける人が多い。したがつて特発性脳内血腫という場合には，外傷以外のすべての原因によるものを含むので，高血圧性脳内出血が大きな比率を占める。Russell^28）の特発性頭蓋内出血の剖検例461例の病因分析によつても，高血圧性のものが50％を占めている。

　しかし脳内血腫のなかには，高血圧を有しない比較的若年者におこるもので，もちろん外傷や明らかな血管奇形を有せず，主として大脳半球の白質内に，被膜を有する凝血を混じた血液貯留として発見されるものがあり，このようなものは，いわゆる卒中型の発病型式をとらず，徐々に脳圧充進症状と局所神経学的症状が発展してきて，脳腫瘍に類似した経過をとり，手術によつてはじめて血腫が発見されるものが多く，したがつて手術の予後も高血圧性脳内血腫に較べるとはるかによいものである。

Although majority of intracerebral hematoma is a result of trauma, rupture of aneurysm or arteri-ovenous malformation, and hypertensive cerebral hemorrhage, it sometimes takes place in younger generation without apparent cause. Such particular type of intracerebral hematoma is usually not as-sociated with sudden onset, and is characterized by progressive development of the signs of raised in-tracranial pressure and of neurological deficits. Therefore, the patients are apt to be brought into operation under a diagnosis of brain tumor. In ad-dition, the patients usually show dramatic postopera-tive recovery, whereas the surgical results of clas-sical hypertensive capsular hematoma is frustrating.

Four cases of such non-hypertensive spontaneous intracerebral hematoma have been encountered in our department. All of them have shown satis-factory recovery following surgical evacuation of hematomas.

Two of them had experienced minor head injury serveral years prior to admission. However, trauma was thought to have nothing to do with the direct cause of hemorrhage, because the intracerebral clot appeared to be relatively fresh in nature.

Some investigators emphasized the presence of small vascular malformation as a source of bleeding. Though a small anomalous vascular shadow was demonstrated on preoperative angiograms in one of our patients, actual recognition of vascular anomaly was unable to be made macro- and microscopically at the operation.