Prevalence and Length of Cavum Septi Pellucidi in Normal Adult Human Brains Using Magnetic Resonance Imaging

Purpose: In view of the fact that the reported prevalence of cavum septi pellucidi (CSP) in normal adult human brains varies enormously from 0.1% to 87.5% and that this prevalence has not been yet studied in Iran, this study was designed to determine the prevalence and length of CSP in normal adult human brains using magnetic resonance imaging (MRI). Materials and Methods: 29 healthy volunteers (21 males, 8 females) between the ages 17-65 (36.52æ 12.66) were included in this study after verification of their health through - general health questionnaires (GHQ-28). All the subjects underwent a 3-D brain MRI of full coronal series, 1.5 mm slices without interslice gaps. CSP was assessed by counting the number of slices containing CSP (n). The length of CSP was calculated by multiplying the number of slices containing CSP (n) by the thickness of slices (1.5 mm). The cavum septi pellucidi was categorized in two ways. In the first classification, CSP was considered as normal if n=1-3 and as abnormal if nA4 (the length of cavity A6 mm). In the second classification, CSP was categorized as small if n=1-2 and as large if nA4. Finally, the data were analyzed by Fisher's exact test and Spearman's Rho test. Results: This study showed that the CSP was present in 62.1% of normal adult human brains. In 72.2% of the normal adults who had CSP, the size of the cavity was normal and in the other 27.8%, the CSP was abnormal. If n=3 was omitted from the study, in 68.8% of the normal adults who had CSP, the size of the cavity was small and in the other 31.3%, the CSP was large. Although the normal females had a greater prevalence of CSP (75%) than the normal males (47.6%), the difference was not significant. The prevalence of abnormal and large CSP was similar between two sexes. There was no correlation between the age and prevalence of CSP or its size. Conclusion: The CSP is a congenital brain anomaly in more than half of the normal adult population. In most normal adult people, the length of the cavity is less than 6mmand limited to the anterior part (near the genu of corpus callosum).