[Normal pressure hydrocephalus. Pre- and postoperative study of 56 cases (author's transl)].

56 patients considered to have a low pressure hydrocephalus were treated between 1973 and 1979 by a ventriculo-atrial shunting, using a medium pressure Holter valve. Apart from a standard clinical examination, these patients underwent a pneumoencephalography, an isotope cisternography, a measurement of ventricular pressure, and a determination of the C.S.F. resistance to flow by mean of an infusion test. A 6 months to 5 years follow up study showed that the operative result could be considered a success in 47%, a failure in 53%. No precise correlation could be found between any clinical sign or response to investigations, and the functional results. However, an early and really unsteady gait, an important ventricular enlargement without image of cortical atrophy, and the presence of pressure waves on I.C.P. recordings, seem to be frequently associated with good results.