Development of a de novo arteriovenous malformation after bilateral revascularization surgery in a child with moyamoya disease.

The development of a de novo arteriovenous malformation (AVM) in patients with moyamoya disease is extremely rare. A 14-year-old girl developed an AVM in the right occipital lobe during the 4-year postoperative period following successful bilateral revascularization surgeries. She suffered a transient ischemic attack with hemodynamic compromise of the bilateral hemispheres at the age of 10 years. Results of an initial examination by 1.5-T MRI and MR angiography satisfied the diagnostic criteria of moyamoya disease but failed to detect any vascular malformation. Bilateral direct and indirect revascularization surgeries in the anterior circulation relieved her symptoms, and she underwent MRI and MR angiography follow-up every year after surgery. Serial T2-weighted MRI revealed the gradual appearance of flow voids in the right occipital lobe during the follow-up period. Magnetic resonance angiography ultimately indicated the development of an AVM 4 years after these surgeries when catheter angiography confirmed the diagnosis of an AVM in the right occipital lobe. The AVM remained asymptomatic, and the patient remained free of cerebrovascular events during the time she was observed by the authors. Acquired AVM in moyamoya disease is extremely rare, with only 3 pediatric cases including the present case being reported in the literature. The development of a de novo AVM in a postoperative patient with moyamoya disease appears to be unique, and this case may provide insight into the dynamic pathology of AVMs.