[Reversible stenosis of posterior cerebral artery after surgical revascularization for quasi-moyamoya disease: a case report].

The authors report a 32-year-old male who presented transient stenosis of the bilateral posterior cerebral artery (PCA) one week after right STA-MCA anastomosis and indirect bypass for quasi-moyamoya disease associated with Down syndrome. The bilateral PCA were intact on both cerebral angiography and MRA before surgery. One week after surgery, the patient suddenly developed left homonymous hemianopsia. Diffusion-weighted MRI revealed newly developed cerebral infarction in the bilateral MCA-PCA watershed zone. Simultaneous MRA revealed marked stenosis of the bilateral PCA. Follow-up MRA taken 5 months later showed that the stenosis of the bilateral PCA completely resolved. Although the precise mechanism of reversible PCA stenosis is still unknown, the phenomenon may play an important role in disease progression in patients with moyamoya or quasi-moyamoya disease.