Does idiopathic normal pressure hydrocephalus always mean a poor prognosis?

The objective was to assess whether idiopathic normal-pressure hydrocephalus (iNPH) has a worse prognosis than other forms of hydrocephalus, as has been suggested.

A total of 125 patients with chronic hydrocephalus, 75 of whom suffered from iNPH and the remaining (non-INPH) from sNPH or non-communicating hydrocephalus, were shunted using gravitational valves. Clinical state was assessed with our clinical grading (KI) and a co-morbidity index (CMI). Average follow-up was 5.1 +/- 1.6 years.

Spearman, Kruskal-Wallis, ANOVA, chi(2)- and the Wilcoxon U tests at a significance level of pi < 0.05 were used.

Shunt responder rates for iNPH and non-iNPH were 72% and 86%, respectively. With shorter anamnesis (< or =1 year) or preoperative KI < 6 points, iNPH patients had a similar or even better outcome than non-iNPH patients with longer anamnesis or a worse KI. Most impressive was the influence of co-morbidity: 86% of iNPH patients with a low CMI (< or =3 points) experienced clinical improvement after shunting, which was contrasted by a responder rate of 64% for non-iNPH with worse CMI.

The diagnosis of iNPH does not by itself mean a worse prognosis, and iNPH patients with favorable preconditions may have a similar or better prognosis than patients with any other kind of hydrocephalus. The worse overall clinical results of iNPH result from late recognition and in most instances worse preconditions.