Prevalence of Septum Pellucidum Variations: A Retrospective Study

Abstract

Background: The septum pellucidum is a vertical double membrane, extending from the lower surface of the corpus callosum to the fornix. Cavum septi pellu-cidi (CSP) is a cavity formation between the two membranes that separate the septum pellucidum from the anterior horn of the lateral ventricle. Cavum vergae (CV) is the extension of the cavity between the two leaflets posterior to the splenium of the corpus callosum. In addition, another cystic variation, cavum velum interpositum (CVI), can be found at the level of crus fornices and corpus pineale. The aim of the present study was to retrospectively determine the type and prevalence of septum pellucidum variations in the adult population using Magnetic resonance imaging (MRI). Methods: Using a retrospective study design, the presence of septum pellucidum variations was investigated in 3128 patients aged 18 - 80 years. The variations were defined as either CSP or CV on sagittal, axial, coronal T1- and T2-weighted images. In addition, the presence of CV and septum pellucidum agenesis was evaluated. Results: No variation was found in the septum pellucidum in 93.82% of cases. CSP was the most frequent variation with a prevalence of 3.7%. CV had a prevalence of 3.1%. Apart from these variations, CVI was observed in 1% of all cases. Conclusion: Embryological development of the septum pellucidum and the neighboring anatomical structures occurs simultaneously. The authors believe that the present study might serve as a preliminary study for other clinical studies related to these variations.