Third ventriculostomy in normal pressure hydrocephalus.

Improvement in three out of four cases of normal pressure hydrocephalus after third ventriculostomy is reported. Pre- and postoperative ventricular pressure recording suggested that this improvement may be occurring in the absence of an improvement in ventricular pressures. Third ventriculostomy may relieve periventricular tissue stress and thus improve local blood flow, which is a likely mechanism in the syndrome of normal pressure hydrocephalus.