Cortical blindness: an unusual complication after removal of a ganglioneuroma of the neck.

A 5-year-old girl was operated upon after a huge mass had been found on the left side of her neck. Preoperatively the anatomy was studied using MRI, including 3D-reconstruction of the tumor. The left vertebral artery was seen to cross the tumor, and during the operation the vessel was preserved. Postoperatively it thrombosed and a permanent cortical blindness developed. One year later MRI angiography of the intracerebral vessels was performed and a pre-existing anomaly of the circle of Willis was demonstrated, which had contributed to the development of the cortical blindness.