title: Estimated ventricle size using Evans index: reference values from a population-based sample.
abstract: Evans index is an estimate of ventricular size used in the diagnosis of idiopathic normal-pressure hydrocephalus (iNPH). Values >0.3 are considered pathological and are required by guidelines for the diagnosis of iNPH. However, there are no previous epidemiological studies on Evans index, and normal values in adults are thus not precisely known. We examined a representative sample to obtain reference values and descriptive data on Evans index.
  
  
  
  A population-based sample (n = 1235) of men and women aged ≥70 years was examined. The sample comprised people living in private households and residential care, systematically selected from the Swedish population register. Neuropsychiatric examinations, including head computed tomography, were performed between 1986 and 2000.
  
  
  
  Evans index ranged from 0.11 to 0.46. The mean value in the total sample was 0.28 (SD, 0.04) and 20.6% (n = 255) had values >0.3. Among men aged ≥80 years, the mean value of Evans index was 0.3 (SD, 0.03). Individuals with dementia had a mean value of Evans index of 0.31 (SD, 0.05) and those with radiological signs of iNPH had a mean value of 0.36 (SD, 0.04).
  
  
  
  A substantial number of subjects had ventricular enlargement according to current criteria. Clinicians and researchers need to be aware of the range of values among older individuals.
authors.affiliation: Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.|Neuropsychiatric Epidemiology Research Unit, Gothenburg, Sweden.|Hydrocephalus Research Unit, Gothenburg, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Jaraj
authors.affiliation: Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.|Hydrocephalus Research Unit, Gothenburg, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Rabiei
authors.affiliation: Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.|Neuropsychiatric Epidemiology Research Unit, Gothenburg, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Marlow
authors.affiliation: Institute of Clinical Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Jensen
authors.affiliation: Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.|Neuropsychiatric Epidemiology Research Unit, Gothenburg, Sweden.
authors.forename: I
authors.initials: I
authors.lastname: Skoog
authors.affiliation: Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.|Hydrocephalus Research Unit, Gothenburg, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Wikkelsø
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002552:Cerebral Ventricles / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D003704:Dementia / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000000981:diagnostic imaging; D008297:Male; D011153:Population; D012016:Reference Values; D012727:Sex Characteristics; D013548:Sweden; D014057:Tomography, X-Ray Computed
keywords: Evans index; dementia; epidemiology; idiopathic normal-pressure hydrocephalus; reference values; ventricular enlargement