[An experience of dissecting cerebral aneurysm of the anterior cerebral artery].

Intracranial dissecting aneurysms have been reported occasionally in recent years. However, excluding dissecting aneurysms which extend from the proximal intracranial carotid artery, dissecting aneurysms arising merely in ACA are found only rarely. We are reporting here a case of a 42 year-old gentleman who did not present any particular causative etiology such as trauma or other basic diseases causing arteritis. Our patient is the 8th case, as far as we could find in the literature, in which the dissection of the arterial wall originated at the ACA. The patient was thought to have a tiny saccular aneurysm at the A 1-2 junction of the right ACA associated with vasospasm in the distal ACA on the angiogram. The patient had motor weakness on the left side and headache as well as a low density area in the territory of the ACA on the CT scan. A craniotomy was performed verifying the aneurysm to be dissecting in type without any sign of recent subarachnoid hemorrhage in the surrounding structures. No aggressive surgical treatment such as trapping of the aneurysm was done because the collateral blood circulation in that territory of the distal right ACA seemed to be poor and the patient no longer had neurological deficit at the time of operation. The patient was treated successfully with antiplatelet therapy. On the follow-up angiogram performed 3.5 months after the onset of the illness, we noted the disappearance of the abnormal angiographical findings of the dissecting aneurysm and distal arterial narrowing (pearl and string sign).(ABSTRACT TRUNCATED AT 250 WORDS)