L'idrocefalo normoteso: problematiche di fisiopatologia e diagnostica

We expose a review of the various hypotheses on the genesis and evolution of the normal pressure hydrocephalus (NPH). Described in 1964 by Hakim, the NPH is characterized by a deterioration of intellective functions, gait difficulty and urinary incontinence. From the beginning few attention has been paid to the biomechanic properties of the cerebral tissue in the liquoral hydrodynamics genesis. Nor the cisternography nor other methods, like the liquoral infusion test, the intracranial pressure (ICP) continuous recording, the CT, the SPECT, the Xenon-CT led to definitive results. Various studies demonstrated variations in ICP curve prophile from normal values to higher ones with continuous "beta" activity, so that in the realm of NPH we must consider active hydrocephalic states alongside with compensated ones. A key pathogenetic role has been attributed to the liquoral outflow resistance (R0) though still a demonstrted linear correlation between R0 and ICP raising is lacking, as well as between R0 and ventricular dilatation. Recently has been introduced the concept of ventricles as thrre-dimensional space entities surrounded by cerebral tissue; the endoventricular pressure could influence the cerebral volume by interacting with the capillary pressure. The raising of ventricular volume (e.g. in the NPH) would provoke a shrinkage of the cerebral tissue, by a reduction in its interstitial fluid containt, so, the NPH could be caused by an alteration in this mechanism