title: 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.
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.
  
  
  BACKGROUND
  The study has been registered at clinicaltrials.gov, identifier NCT00874198.
authors.affiliation: Hydrocephalus Research Unit, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden. Carsten.Wikkelso@neuro.gu.se
authors.forename: Carsten
authors.initials: C
authors.lastname: Wikkelsø
authors.forename: Per
authors.initials: P
authors.lastname: Hellström
authors.forename: Petra Margarete
authors.initials: PM
authors.lastname: Klinge
authors.forename: Jos Th J
authors.initials: JT
authors.lastname: Tans
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002557:Cerebrospinal Fluid Shunts; D003072:Cognition Disorders / Q000209:etiology; D004185:Disability Evaluation; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid* / Q000175:diagnosis* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D012307:Risk Factors; D016896:Treatment Outcome