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[Aneurysms of the distal anterior cerebral artery. Report of 18 cases and review of 191 reported cases].

Of 344 patients with intracranial aneurysms treated at the Shimane Medical University and Mat sue Red Cross Hospital, eighteen (5.2%) had aneurysms of the distal anterior cerebral artery (DACA). Five were male and thirteen were female. Their ages ranged from 39 to 67 years. Seven teen patients had had at least one episode of subarachnoid hemorrhage (SAH) caused by rupture of the aneurysm of DACA. Motor disturbance found in 8 cases was a rather specific clinical feature on admission. There were 4 cases with hemiparesis predominant in the lower limb, 3 with monoparesis of a leg, and 1 with tetraparesis. Six of the aneurysms were located at the bifurcation of the pericallosal artery (PCA) and callosomarginal artery, 6 at the bifurcation of PCA and anterior inter nal frontal artery, 3 at the distal end of azygos anterior cerebral artery (ACA), and 3 on the peripheral PCA. Eleven aneurysms were on the left side, 4 on the right, and 3 on the midline. Six pa tients were shown to have multiple aneurysms. Azygos ACA was noted in 3 cases and bihemispheric ACA in 2. In 7 cases, PCA made a sharp bend at the genu of the corpus callosum where the aneurysm was located. Computerized tomography (CT) scans were done in 6 cases. Blood was found in the basal cisterns and bilateral Sylvian fissures in symmetrical distribution, and extended into the anterior interhemispheric fissure and pericallosal cistern in all six. Two cases had a large in tracerebral hematoma in the corpus callosum. Direct surgical attack on the aneurysm was made in 17 cases. Long-term follow-up results revealed that 10 cases had no neurological deficits, 2 had minimal deficits, 2 were moderately disabled, and 3 died. From an analysis of these 18 cases and 191 cases reported in the literature, the following results were obtained: 1) The incidence of DACA aneurysm was approximately 5%. There was no difference in sex distribution, and most cases were found in the fifth to sixth decade. 2) Seventy-one percent were located at the pericallosal bifurcation, 15% in the infracallosal portion of PCA, and 6% on the supracallosal portion. Multiple aneurysms were found in 29%. 3) Leg monoparesis and predominantly crural hemiparesis may be rather specific clinical features. 4) Anomalies and anatomical variations of DACA were found, such as azygos ACA, bihemispheric ACA, supreme anterior communicating artery, and acute angulation of PCA at the genu of corpus callosum.