Arachnoid cyst causing obstructive hydrocephalus Luis Izquierdo, MD Article Published: Apr 17, 2003 Miami, Florida This is a case of arachnoid cyst, towards the base of the skull at the level of the circle of Willis. It seemed that the posterior cerebral and the posterior communicating vessels are displaced.  The power Doppler shows circulation to middle cerebral artery and anterior vessels. A repeat examination 3 weeks later demonstrated obstructive hydrocephalus as a complication. Discussion Board Start a discussion about this article Add to Favorites Favorite