Failure of endoscopic third ventriculostomy in the treatment of idiopathic normal pressure hydrocephalus.

Even though the main indication for neuroendoscopic management of normal pressure hydrocephalus (NPH) is the presence of an aqueductal block, recent reports suggest the possible efficacy of endoscopic third ventriculostomy (ETVS) in idiopathic NPH. We present 14 cases with apparently idiopathic NPH treated by ETVS, and report on the low rate of success (21 %). A closer analysis of the successful cases reveals possible elements which may explain the good outcome, and should be taken into consideration when defining the best strategy to address NPH.