Magnetic resonance angiography demonstrating adult moyamoya disease progressing from unilateral to bilateral involvement--case report.

A 21-year-old woman presented with moyamoya disease manifesting as speech disturbance and right quadrant hemianopsia on October 22, 1994. Magnetic resonance (MR) angiography showed occlusion of the left internal carotid artery (ICA) with the normal right ICA. The diagnosis was "unilateral" moyamoya disease by conventional angiography. Follow-up MR angiography revealed further occlusive changes of the right middle cerebral artery (MCA) trunk on July 30, 1995, which progressed to occlusion of the MCA on March 25, 1997. Conventional angiography confirmed occlusion of the right terminal ICA to MCA with basal moyamoya vessels. The diagnosis was "bilateral" moyamoya disease. She was successfully treated by bilateral superficial temporal artery-MCA anastomosis. Follow-up MR angiography should be performed in relatively young patients with "unilateral" moyamoya disease to detect any progression to bilateral moyamoya disease.