RT Journal Article SR Electronic T1 Arachnoid cyst of the posterior fossa JF Neurosciences Journal JO Neurosciences (Riyadh) FD Prince Sultan Military Medical City SP 277 OP 279 VO 15 IS 4 A1 Mohammed Aggouri A1 Said A. Boujraf A1 Mohammed Benzagmout A1 Mohammed E. Chaoui YR 2010 UL http://nsj.org.sa/content/15/4/277.abstract AB Arachnoid cysts of the posterior fossa are uncommon. Our case of a 49-year-old man presented with a 2 month history of headaches, nausea, and vertigo associated with walking instability. An MRI revealed a median well-circumscribed cystic lesion of the posterior fossa, with similar signal characteristics to CSF, and without connection to the fourth ventricle. This aspect suggested either arachnoid or hydatid cysts. Direct open surgery was performed allowing complete removal of the cyst wall, with a good outcome.