Chiasmatic arachnoiditis and empty sella: report and discussion of a case.

The case is presented of a 5-year-old boy with progressive visual loss and physical findings suggestive of pituitary dysfunction. A craniotomy revealed opticochiasmatic arachnoiditis and empty sella. The concomitance of these conditions has not been reported. Both entities are associated with arachnoid cysts or cyst-like swellings of the arachnoid, according to the literature. It is proposed that a primary arachnoid cyst may have displaced the pituitary in the sella resulting in secondary inflammatory responses which affected the chiasm. An alternate, but similar explanation, would involve a perichiasmatic arachnoiditis of unknown cause resulting in cystic invasion of the sella. Rupture of the presumed cyst is believed to have occurred late in the preoperative course, and to have been responsible for aggravation of the symptoms.