title: Computerized tomographic study of normal Evans index in adult Nigerians.
abstract: BACKGROUND
  The evaluation of degree of ventricular enlargement should be based on established indices rather than on personal experience as this is highly subjective. Our aim was to establish normal values for Evans index in a Nigerian adult population as none has been found in the Nigerian medical literature.
  
  
  METHODS
  Axial computerized tomographic brain scans of 488 normal subjects were reviewed retrospectively. Of them, 319 (65.36%) of the patients were males and 169 (34.63%) were females; their ages ranged from 18 to 84 years with a mean age of 37.26 years. The images were acquired using a multi-slice GE Sigma excite scanner. Evans index was measured as the linear ratio of the total width of the frontal horns of the cerebral lateral ventricles to the maximum intracranial diameter.
  
  
  RESULTS
  The mean value for Evans index for the studied population was 0.252 ± 0.04. The EI increased with age and it was slightly higher among males. The difference in Evans value in males and females was not statistically significant. Individuals above 60 years old had the highest Evans values in both sexes.
  
  
  CONCLUSIONS
  This study has established ranges of normal value for Evans index in a Nigerian population. It agrees with the diagnostic cut-off value of > 0.3 for hydrocephalus and it compares well with that of the Caucasians.
authors.affiliation: Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna, Nigeria.
authors.forename: Ahmed Umdagas
authors.initials: AU
authors.lastname: Hamidu
authors.affiliation: Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna, Nigeria.
authors.forename: Sefiya Adebanke
authors.initials: SA
authors.lastname: Olarinoye-Akorede
authors.affiliation: Department of Anatomy, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna, Nigeria.
authors.forename: David Solomon
authors.initials: DS
authors.lastname: Ekott
authors.affiliation: Department of Anatomy, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna, Nigeria.
authors.forename: Barnabas
authors.initials: B
authors.lastname: Danborno
authors.affiliation: Department of Surgery, Neurosurgery Unit, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna, Nigeria.
authors.forename: Muhammad Raj
authors.initials: MR
authors.lastname: Mahmud
authors.affiliation: Department of Medical Microbiology, Ahmadu Bello University Teaching Hospital, Zaria, Kaduna, Nigeria.
authors.forename: Muhammad Shakir
authors.initials: MS
authors.lastname: Balogun
keywords: Computerized tomography; Evans index; Nigeria; normal; normal adults