[An autopsy case of a persistent primitive trigeminal artery aneurysm].

A case of an aneurysm on the persistent primitive trigeminal artery (PPTA) is reported. A seventy-five-year-old woman with subarachnoid hemorrhage was admitted to the Hospital six hours after the onset. She was lethargic and had stiffness of her neck with severe headache and vomiting. Computed tomographic examination showed marked subarachnoid hemorrhage in the basal cisterns, especially in the ambient cistern on the right side. Cerebral angiogram revealed the right PPTA having a saccular aneurysm on the trunk. Her advanced age and the special location of the aneurysm did not allow direct operation in the acute stage. She died of rebleeding of the aneurysm thirty days after admission. Pathological study showed that the PPTA was originated from the cavernous portion of the right internal carotid artery and joined to the cephalad portion of the basilar artery. The aneurysm, 10 X 7 mm in size, was located at the curved midportion of PPTA, 9 mm proximal to the basilar artery. The proximal portion of the PPTA to the aneurysm had severe arteriosclerosis, whereas the distal portion showed less sclerotic change. However, there were no evidences of developmental anomaly in the wall of the PPTA. Eighteen cases of PPTA with the aneurysm arisen from PPTA itself or at its junction with internal carotid artery have been previously reported. PPTA in any case has not been examined pathologically. It has been speculated that dysplasia of the PPTA wall contributes to initiating the aneurysm on the PPTA. However our histopathological examination of the PPTA revealed no evidence of dysplasia in the PPTA wall.(ABSTRACT TRUNCATED AT 250 WORDS)