Subarachnoid hemorrhage (subarachnoid hemorrhage)

Japanese: くも膜下出血(蜘蛛膜下出血) - くもまくかしゅっけつ（英語表記）subarachnoidal hemorrhage

This refers to bleeding that occurs in the subarachnoid space (the space between the pia mater and the arachnoid membrane) from the arteries and veins running along the surface of the brain and spinal cord. Because the subarachnoid space is filled with cerebrospinal fluid, in this case the bleeding is not limited to a local area, but spreads throughout the cerebrospinal fluid of the brain and spinal cord. Causes of subarachnoid hemorrhage include head trauma, cerebral aneurysms, and cerebral arteriovenous malformations. Subarachnoid hemorrhage accounts for 8% of all cerebrovascular disorders, and about 70% of these are caused by ruptured cerebral aneurysms. Including unruptured cerebral aneurysms, cerebral aneurysms are found in about 1% of the total population, making them a common occurrence.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

脳･脊髄表面を走る動･静脈からくも膜下腔(軟膜とくも膜との間の間隙)に起こった出血をいう。くも膜下腔は髄液で満たされているので，この場合出血は局所にとどまらず，脳･脊髄の髄液全体に拡散する。くも膜下出血の原因としては，頭部外傷，脳動脈瘤，脳動静脈奇形などがある。全脳血管障害の8％をくも膜下出血が占め，その約70％が脳動脈瘤の破裂によるものである。未破裂のものも含めると，脳動脈瘤は全人口の1％ほどに見いだされ，発生頻度が高い。

出典　株式会社平凡社世界大百科事典第２版について　情報

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