末梢性前大脳動脈瘤

ANEURYSMS OF THE PERIPHERAL ANTERIOR CEREBRAL ARTERY

I．緒言

　前大脳動脈瘤はその局在により3群に分けられる。すなわち，（1）交通動脈前部（Flsher A₁），（2）前交通動脈分岐部（A₁，A₁の境界点），（3）前交通動脈分岐部より末梢部（A₁およびそれ以後）に発生するものである。

　これらの動脈瘤は同一動脈より発生するものではあるが，その局在の相違により症候学的特徴またその外科的治療方針において，それぞれ特有な問題を持つている。これらの各動脈瘤の発生頻度は（2）でもつとも高く，つぎに（3），（1）の順序である。（1）の動脈瘤は前大脳動脈の外側前穿通動脈より発生するが，その発生場所がHeubner動脈より近位か遠位かの局在が発生する症状を理解するうえにたいせつなことはCritchley （1930）^9）の精力的膨大な論文において強調された。

Aneurysms of the peripheral anterior cerebral artery are relatively uncommon and range from 2.5 to 5.5% of incidence in statistics reported by many authors. In this paper 6 cases of the peripheral anterior cerebral aneurysm are reported and their clinical data, radiological findings and operations are discribed.

Incidences of anomalies of the anterior cerebral artery coexisting with aneurysm are significantly higher than the statistical incidences reported from ordinary autopsies and this fact suggests these de-velopmental anomalies of the artery might play crucially important roles in the development of this aneurysm.

Rupture of this aneurysm develops rather charac-teristic symptoms by extravasation of blood and in-duction of arterial spasm, earring out what is in fact a more or less posteriorly placed leucotomy or cin-gulectomy with all the untoward effects of it as im-parment of consciousness, psychic symptoms, motor and sensory disturbances dominant on the lower limb and disturbance of micturition. It is also emphasized that especially the left peripheral anterior cerebral aneurysm shows more serious than the right.

One case which failed to recover to an operable stage died of her third haemmorrhage. Other five cases were operated on by approaching along the medial aspect of the frontal lobe and wrapping, clipping or ligating aneurysm. There was no oper-ative or remote mortality. When an aneurysm itself horizontally bilobular on its antero-posterior view of angiography, special precaution should be always kept in mind in its dissecting process because of possible nesting of its partial aneurysmal lobule in the adjacent brain substance and also not to injure its parent artery during operation.

During convalescent period 3 cases showed mild temporary psychic symptoms, showing euphoria, illusion, akinetic mutism and catatonia ; 2 of 3 show-ed temporary urinal incontinence and 1 showed per-sisting hemiplegia. All these 3 cases had aneurysm of the left anterior cerebral artery treated with silver clipping and this fact might emphasize the speciality and subtlety of the left anterior cerebral aneurysm in the clinical and therapeutic points of view.