title: Incidence of Idiopathic Normal-Pressure Hydrocephalus in Northern Spain.
abstract: BACKGROUND
  Although the incidence of idiopathic normal-pressure hydrocephalus (iNPH) can be 1.20 cases/1000 inhabitants/year in individuals ≥ 70 years old, in most series, the incidence of shunt-responsive iNPH appears to be <1/100,000 inhabitants/year. We report the results of a prospective 10-year longitudinal study of the incidence of iNPH in a northern Spanish population.
  
  
  METHODS
  In a stable population of 590,000 inhabitants served by a single neurosurgical department, we periodically asked all primary care practitioners, neurologists, and geriatricians to refer for iNPH screening any patient with ventricular dilation who was complaining of motor disturbances, cognitive impairment, or sphincter dysfunction.
  
  
  RESULTS
  From January 2003 to December 2012, 293 patients were referred with suspected normal-pressure hydrocephalus. In 187 patients, iNPH was diagnosed; 89 of these patients were classified as probable iNPH, and 98 were classified as possible iNPH. Cerebrospinal fluid diversion was performed in 152 patients, and 119 showed a good outcome. The incidence of iNPH was significantly greater in male patients and patients >60 years old and increased exponentially with age. After age 60, the standardized age- and sex-adjusted incidence rates for iNPH, shunt surgery for iNPH, and shunt-responsive iNPH were 13.36 cases/100,000 inhabitants/year, 10.85 cases/100,000 inhabitants/year, and 8.55 cases/100,000 inhabitants/year. No differences were detected in the response rate between probable and possible iNPH (80.52% vs. 76.00%; P = 0.497).
  
  
  CONCLUSIONS
  Even with a protocol for patient referral in place, reported iNPH incidence was lower than predicted, reflecting a persistent problem of underdiagnosis in our population.
authors.affiliation: Department of Neurosurgery-Spine Unit, University Hospital "Marqués de Valdecilla", Santander, Spain. Electronic address: rmlaez@yahoo.es.
authors.forename: Rubén
authors.initials: R
authors.lastname: Martín-Láez
authors.affiliation: Department of Neurosurgery-Spine Unit, University Hospital "Marqués de Valdecilla", Santander, Spain.
authors.forename: Hugo
authors.initials: H
authors.lastname: Caballero-Arzapalo
authors.affiliation: Section of Neuroradiology, University Hospital "Marqués de Valdecilla", Santander, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Valle-San Román
authors.affiliation: Department of Neurosurgery-Spine Unit, University Hospital "Marqués de Valdecilla", Santander, Spain.
authors.forename: Luis Ángel
authors.initials: LÁ
authors.lastname: López-Menéndez
authors.affiliation: IKERBASQUE, Basque Foundation for Science, University of Deusto, Bilbao, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Arango-Lasprilla
authors.affiliation: Department of Neurosurgery-Spine Unit, University Hospital "Marqués de Valdecilla", Santander, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Vázquez-Barquero
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002557:Cerebrospinal Fluid Shunts; D060825:Cognitive Dysfunction / Q000209:etiology; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000601:surgery; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D000068079:Motor Disorders / Q000209:etiology; D018579:Patient Selection; D011446:Prospective Studies; D012737:Sex Factors; D013030:Spain / Q000453:epidemiology; D016896:Treatment Outcome
keywords: Cerebrospinal fluid shunts; Epidemiology; Idiopathic normal-pressure hydrocephalus; Incidence; Shunt-responsive hydrocephalus; Ventriculomegaly