Third ventriculostomy for acquired non-communicating hydrocepahlus is an ex
cellent alternative to shunting procedures. Nevertheless, complications can
be severe and even fatal (e.g., lesion of the basilar artery), especially
if the floor of the 3(rd) ventricle is very tough and/or opaque. The author
s describe a safe method of sharp perforation of the floor, which should be
applied if blunt fenestration cannot be achieved easily.