ABSTRACT
The authors describe the case of a 60-year-old patient with basilar artery aneurysm who in time developed normal pressure hydrocephalus (NPH). Clinical examinations and laboratory tests did not reveal other data from which the pathology could be attributed to causes other than the vascular malformation already considered. The mechanical obstruction exerted by the aneurysm lodged on the floor of the third ventricle represents, according to the authors, the physiopathogenetic mechanism by which a temporal delay is developed between the endoventricular pulsation and that of the cerebral veins so as to produce a precise pulsatile gradient in a centrifugal direction to allow the formation of an active hydrocephalus proportional to the entity of cerebrospinal fluid (CSF) pulse.
