Dissection of anterior cerebral artery presenting with cerebral infarction in contralateral frontal lobe

Although diagnosis of dissection in the anterior cerebral artery (ACA) has increased, cerebral infarction in frontal lobe due to contralateral ACA dissection is rare. A 52-year-old woman developed headache and motor weakness in the left hemibody. Magnetic resonance images demonstrated a fresh cerebral infarction in the right frontal lobe and thin right ACA. The initial diagnosis was a cerebral infarction in the right frontal lobe due to right ACA stenosis. Angiography performed nine days after onset showed dilatation and stenosis of the left ACA, and a small diameter of the right ACA. An intramural thrombus in the left ACA was demonstrated on MRI. The diagnosis was a cerebral infarction in the right frontal lobe due to dissection of the contralateral left A2 and A3 of ACA. There is a possibility that cerebral infarction in frontal lobe is induced by the contralateral ACA abnormality in a case with bihemispheric ACA.