The predictive value of ventricular CSF removal in normal pressure hydrocephalus

We report the impact of diagnostic ventricular CSF removal (VCR) on the gait disturbance in 24 patients with suspected normal pressure hydrocephalus (NPH) who had an intraventricular catheter for studies of CSF dynamics in order to select patients for shunt surgery. There were no complications related to removal of 24 ml CSF over a period of 6 hours in four instances or to the removal of 15-18 ml at one time in twenty instances. Seventeen out of 24 patients were diagnosed as having NPH. Two of those patients who had relatively mild symptoms had a prolonged amelioration of their gait disturbance after diagnostic VCR. Thirteen patients underwent subsequent shunt operations. Eleven of them had good functional and symptomatic improvement on follow-up. In those six patients who had a marked amelioration of their gait disturbance after diagnostic VCR, not only improvement of the gait disturbance was observed after shunting, but a consistent overall improvement as well. The predictive value of VCR was more variable in those six patients who had only a moderate response to VCR. No change of the gait disturbance after VCR was noted in seven patients in whom the diagnosis of NPH was not confirmed. Diagnostic VCR might be a valuable ancillary test in specialized centers which routinely use intraventricular CSF monitoring in the selection of patients for shunt surgery.