大動脈縮窄に合併する脳動脈瘤

CEREBRAL ANEURYSMS ASSOCIATED WITH COARCTATION OF THE AORTA

I．はじめに

　脳動脈瘤の病因をめぐつて，先天性説，後天性説，あるいはその双方を重視するものと大略3つの立場があるが，脳動脈瘤に先天奇形，ことに血管系の異常を高率に合併するかどうかが一つの焦点になつている。大動脈縮窄は脳動脈瘤を合併することが多いが，この際の脳動脈瘤の成因についても，従来の先天奇形の合併という考え方に対して，大動脈縮窄に因ずく高血圧症と血管壁の退行変性が脳動脈瘤形成に関係しているという考えがうちだされている。

　最近，当施設で経験した2例の大動脈縮窄に合併した脳動脈瘤の症例を報告し，この合併病態について若千の文献をもとに検討を加える。又，脳動脈瘤手術に低血圧麻酔が導入されて，悩外科医にとつて大きな福音となつているが，大動脈縮窄がある場合には体循環，脳循環動態の異常が存在するため，低血圧麻酔による腎あるいは脳の血行不全に対して考慮を払わねばならないことを，症例の経験から強調したい。

Coarctation of the aorta was associated in two cases out of 195 patients of intracranial aneurysms admitted during past seven years. The patients were a 38-year-old woman who had usual type of coarctation of the aorta and a 15-year-old boy whose stenosis was preisthmic: both patients were admitted with subarachnoid hemorrhage due to rupture of the anterior communicating aneurysm and were successfully operated on.

Concerning the pathogenesis of the cerebral aneurysm associated with coarctation of the aorta, questions are in debates whether the aneurysm is of congenital nature or the result of concomitant hypertension and premature atherosclerosis seccn-dary to coarctation of the aorta.

Coarctation of the aorta is a rare congenital anomaly and about 10% of the patients dies of intracranial hemorrhages. The incidence of cerebral aneurysm with coarctation of the aorta is much higher than that in the general population. Esti-mating from the previous reports and our experi-ence, neurosurgeons may have a chance to encounter the associated coarctation out of 100 to 250 aneu-rysmal patients. The motality due to this con-comitant lesions is extremely high, if not treated, and the prompt diagnosis and surgical treatment for both the intracranial and cardiac lesions should be applied.

Induced hypotension is now a choice of anesthesia for aneurysmal surgery, but, in case of intracranial aneurysm associated with coarctation of the aorta, the effect of reduced blood flow to the organs supplied by poststenotic arteries should be taken into account.