DOES SELECTION BIAS DETERMINE THE PREVALENCE OF THE CAVUM SEPTI PELLUCIDI

This study was undertaken to ascertain the prevalence of the persisten t cavum septi pellucidi in children and adults by magnetic resonance i maging (MRI) and to compare the clinical indications for neuroimaging in the two age groups as a measure of group selection bias. All scans performed at West Virginia University during 1997 were reviewed for th e presence of a persistent cavum septi pellucidi, The clinical indicat ions for the MRI study were determined in 100 consecutive adult (17 ye ars of age or alder) and 100 consecutive pediatric (younger than 17 ye ars of age) scans. In the 203 pediatric patients the prevalence of a p ersistent cavum septi pellucidi was 6.9%, and in the 814 adults the pr evalence was 2.1%, Mental retardation/developmental delay was the clin ical indication for at least 26% of the pediatric patients but was not an indication for neuroimaging in the adult study group. The known as sociation of persistent cavum septi pellucidi with mental retardation and in several groups of patients with conditions clinically character ized by mental dysfunction suggests that the higher prevalence in the pediatric study group may primarily be the result of the patient selec tion bias operating through the different clinical indications for neu roimaging in the two populations. (C) 1998 by Elsevier Science Inc, Al l rights reserved.