[A case of suprasellar arachnoid cyst followed up for a long time].

We followed a case of suprasellar arachnoid cyst for 12 years. The patient was a sixteen-year-old girl without particular problems in her general condition. She showed optic atrophy in both eyes and optic nerve hypoplasia with an inferotemporal quandranopsia in the left eye. A suprasellar arachnoid cyst communicating with the tubarachnoid space was found to extend into the sella turcica as an empty sella. A cyst wall was resected and a cyst-peritoneal shunt performed. After 12 years from the operation, sensitivity was slightly depressed in the visual field where it had already been disturbed. Although there are few reports in the literature on involvement of the optic nerves and chiasma by suprasellar arachnoid cysts, papilledema and optic atrophy are often found in children, and infero-temporal quandranopsia or homonymous hemianopsia have been reported. Visual field defects were most likely caused by compression of the optic nerve by cyst or prolonged papilledema. We also suspect that some kind of disturbance to the optic nerve occurred during extension of the arachnoid cyst as an empty sella, or during formation of arachnoid cyst in the fetus stage.