[Dissecting aneurysm of the anterior cerebral artery: report of a case].

A 43-year-old man suddenly experienced severe headaches and involuntary flexion-extension movements of four limbs, which were followed by hypertonic extension of the limbs lasting for a few hours. Two days later, he experienced generalized tonic seizure without loss of consciousness. After the seizures, he remained hemiparetic on the right side. His past medical history was non-remarkable, and the histories of hypertension, diabetes mellitus, head trauma and significant infectious diseases were all denied. Cerebral angiography performed 22 days after the onset showed a segmental, irregular narrowing of the left A2 segment and an aneurysmal outpouching immediately proximal to the stenosis. CT scan revealed a low density area in the left frontal lobe, corresponding to the territory of the involved left anterior cerebral artery. Cerebral angiography was repeated twice in the succeeding 6 months. Each time, the involved A2 segment showed persistence of narrowing, but its shape showed definite changes with the passage of time. A diagnosis of dissecting aneurysm of the anterior cerebral artery was reached by the characteristic angiographic features, and the patient was treated conservatively. Dissecting aneurysm of the cerebral arteries have been reported much less frequently than those of the aorta or other extracranial arteries. Recently, however, such reports are increasing in number, seemingly due to enhancement of knowledge of typical angiographic features, such as string sign, rosette sign, pearl reaction, double lumen and several others. Most of intracranial dissecting aneurysms involve the middle cerebral artery or vertebral-basilar artery, and the ones involving solely the anterior cerebral artery as in this present case are very rare.(ABSTRACT TRUNCATED AT 250 WORDS)