Midline developmental abnormalities of the posterior fossa: correlation of classification with outcome. 
Fifty children with developmental retrocerebellar cysts of the posterior fossa, treated over an 11-year period, were assessed.  The cysts were classified according to a morphological classification based on axial computerized tomography scans in order to assess the usefulness of this classification with regard to treatment and outcome.  There were 35 patients with the Dandy-Walker complex and 15 patients with posterior fossa cysts.  All surgically treated patients had cerebrospinal fluid shunting as the only form of treatment.  Cystoperitoneal shunts were the treatment of choice.  Although the morphological classification has relevance with regard to the embryological development of the cyst, it does not influence the selection of treatment nor the surgical outcome following shunt insertion.