外傷性脳動脈瘤—とくに，大脳鎌の関与について

TRAUMATIC ANEURYSM OF ANTERIOR CEREBRAL ARTERY: IN REFERENCE TO THE ROLE OF CEREBRAL FALX

I．はじめに

　嚢状脳動脈瘤の発生原因には，先天的に内弾性板と中膜の欠損に基く先天説と動脈硬化や動脈壁の変性に基く後天説とある。一方，稀なものとして，細菌による炎症性動脈瘤や外傷に基因する外傷性動脈瘤が挙げられている^12）。しかも，前大脳動脈に発生した外傷性動脈瘤の報告は少ない。われわれは閉鎖性頭部外傷が原因で発生した外傷性前大脳動脈の動脈瘤2症例を経験し，とくに，その1例において，動脈瘤の発生とその増大の様子を追跡しえたので報告する。

We experienced 2 cases of traumatic aneurysmfollowing closed craniocerebral trauma.

Case 1. 8 year old boy: On admission aftercerebral trauma he showed coma, decerebraterigidity, retinal bleeding and conjugate deviationto the right side. Bilateral subdural hematoma wasimmediately removed trephination. An aneurysmwas demonstrated angiographically on the trunk ofthe left pericallosat artery 11 days after trauma.It was accompanied by intracerebral and intraven-ricular hematoma. The neck of the aneurysm wasclipped and the hematoma was removed. Comacontinued for about 3 weeks, and right spastichemiparesis and right hemi-hypaesthesia has remai-ned until the present.

Case 2. 21 year old man: No aneurysm wasvisualized in arteriogram done immediately afterhead trauma, while aneurysm was shown on thebifurcation between the right anterior cerebralartery and the frontopolar artery 7 days aftertrauma. Repeated angiograms demonstrated enlarge-ment and bleb-formation of the traumatic aneurysmfora month. Surgical clipping was done, and his postoperative course was uneventful.

These results lead to the following conclusions:

1) On cranial impulse to the temporal area, follo-wing erebral acceleration and deceleration, anteriorcerebral arteries were stretched, curved and shearedby cerebral falx. Therefore the wall of vessel waspresumably injured. This may be the cause of cere-bral traumatic aneurysm.

2) Angiograms must be carefully scrutinized tovisualize small traumatic aneurysm. Repeat angio-graphy also may be adequate for diagnosis oftraumatic aneurysm 5-10 days after trauma.

3) Surgical clipping of traumatic aneurysm isthe favored treatment because traumatic aneurysmgrows and enlarges usually more rapidly than con-genital berry aneurysm.