DUTCH NORMAL-PRESSURE HYDROCEPHALUS STUDY - RANDOMIZED COMPARISON OF LOW-PRESSURE AND MEDIUM-PRESSURE SHUNTS

Object. The goal of this prospective study was to compare outcome afte r placement of a low-or medium-pressure shunt in patients with normal- pressure hydrocephalus (NPH). Methods. Ninety-six patients with NPH we re randomized to receive a low-pressure ventriculoperitoneal shunt (LP V; 40 +/- 10 mm H2O) or medium high-pressure ventriculoperitoneal shun t (MPV; 100 +/- 10 mm H2O). The patients' gait disturbance and dementi a were quantified by applying an NPH scale, and their level of disabil ity was evaluated by using the modified Rankin scale (mRS). Patients w ere examined prior to and 1, 3, 6, 9, and 12 months after surgery. Pri mary outcome measures were determined by differences between preoperat ive and last NPH scale scores and mRS grades. The LPV and MPV shunt gr oups were compared by calculating both the differences between mean im provements and the proportions of patients showing improvement. Intent ion-to-treat analysis of mRS grades yielded a mean improvement of 1.27 +/- 1.41 for patients with LPV shunts and 0.68 +/- 1.58 for patients with MPV shunts (p = 0.06). Improvement was found in 74% of patients w ith LPV shunts and in 53% of patients with MPV shunts (p = 0.06) and a marked-to-excellent improvement in 45% of patients with LPV shunts an d 28% of patients with MPV shunts (p = 0.12). All outcome measures ind icated trends in favor of the LPV shunt group, with only the dementia scale reaching significance. After exclusion of serious events and dea ths unrelated to NPH, efficacy analysis showed the advantage of LPV sh unts to be diminished. Reduction in ventricular size was also signific antly greater for patients in the LPV shunt group (p = 0.009). Subdura l effusions occurred in 71% of patients with an LPV shunt and in 34% w ith an MPV shunt; however, their influence on patient outcome was limi ted. Conclusions. Outcome was better for patients who had an LPV shunt than for those with an MPV shunt, although most differences were not statistically significant. The authors advise that patients with NPH b e treated with an LPV shunt.