Estimated ventricle size using Evans index: reference values from a population‐based sample

• Published in: European journal of neurology Vol. 24; no. 3; pp. 468 - 474
• Main Authors: Jaraj, D., Rabiei, K., Marlow, T., Jensen, C., Skoog, I., Wikkelsø, C.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.03.2017
• Subjects: Aged; Aged, 80 and over; Algorithms; Annan medicin och hälsovetenskap; Cerebral Ventricles - anatomy & histology; Cerebral Ventricles - diagnostic imaging; dementia; Dementia - diagnostic imaging; epidemiology; Evans index; Female; Humans; Hydrocephalus, Normal Pressure - diagnostic imaging; idiopathic normal‐pressure hydrocephalus; Male; Other Medical and Health Sciences; Population; Reference Values; Sex Characteristics; Sweden; Tomography, X-Ray Computed; ventricular enlargement; epidemiology; dementia; reference values; ventricular enlargement; idiopathic normal-pressure hydrocephalus; Evans index
• DOI: 10.1111/ene.13226
• ISSN: 1351-5101; 1468-1331

Background and purpose 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. Methods 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. Results 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). Conclusions 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.