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Research paper
The European iNPH Multicentre Study on the predictive values of resistance to CSF outflow and the CSF Tap Test in patients with idiopathic normal pressure hydrocephalus
  1. Carsten Wikkelsø1,
  2. Per Hellström1,
  3. Petra Margarete Klinge2,
  4. Jos Th J Tans3,
  5. on behalf of the European iNPH Multicentre Study Group
  1. 1Hydrocephalus Research Unit, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
  2. 2Department of Neurosurgery, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
  3. 3Department of Neurology, Medical Centre Haaglanden, The Hague, The Netherlands
  1. Correspondence to Professor C Wikkelsø, Hydrocephalus Research Unit, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden; Carsten.Wikkelso{at}neuro.gu.se

Abstract

Objective The objective was to determine the sensitivity, specificity, and positive and negative predictive values of the CSF Tap Test (CSF TT) and resistance to CSF outflow (Rout) for the outcome of shunting in a sample of patients with idiopathic normal pressure hydrocephalus (iNPH).

Methods 115 patients were included in this European multicentre study. Diagnosis was based on clinical symptoms and signs, and MRI changes. All patients were treated with programmable ventriculoperitoneal shunts and re-examined 12 months after surgery. Outcomes were measures with a newly developed iNPH Scale and the modified Rankin Scale (mRS). Before surgery, a CSF TT and measurement of Rout was performed, with the results blinded to all caregivers. The 12 month outcome was correlated with Rout and the result of the CSF TT.

Results Rout and the results of the CSF TT showed no correlation with outcome measured by either domain, or with total iNPH score or mRS score. Only an increase in the gait task (10 m of walking at free speed) of the CSF TT correlated significantly (r=0.22, p=0.02) with improvement in iNPH score. The positive predictive value of both tests was >90% and the negative predictive value <20%. Rout >12 had an overall accuracy of 65% and the CSF TT 53%. Combining both tests did not improve their predictive power. No correlation was found between Rout and the results of the CSF TT.

Conclusions Rout and the results of the CSF TT did not correlate with outcome after 12 months. Rout and CSF TT can be used for selecting patients for shunt surgery but not for excluding patients from treatment.

Trial registration The study has been registered at clinicaltrials.gov, identifier NCT00874198.

  • Clinical Neurology
  • Neurosurgery
  • Csf Dynamics
  • Gait
  • Cognition

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