Cave of septum pellucidum

The cave of septum pellucidum (CSP) is a potential midline cavity between the two leaflets of the septum pellucidum. It contains fluid similar to cerebrospinal fluid but is not part of the ventricular system, as it lacks an ependymal and choroid plexus lining and normally does not communicate with the ventricles or subarachnoid space.

Boundaries

Its boundaries are the genu of the corpus callosum anteriorly, body of the corpus callosum superiorly, columns and pillars of the fornix posteriorly, anterior commissure and rostrum of the corpus callosum inferiorly, and the two septal leaflets laterally. Posteriorly, it may be continuous with the cavum vergae.

Developmentally, the septal leaflets begin to fuse at approximately 6 months of gestation, with fusion progressing from posterior to anterior. The cavum septum pellucidi therefore commonly persists at birth but usually closes during the first 3–6 months of life. Persistence beyond infancy is generally an incidental normal anatomical variant when isolated.

Clinical correlates

A simple cavum septum pellucidi is usually asymptomatic. In fetal imaging, visualization of the CSP is an important marker of normal midline forebrain development; its nonvisualization warrants assessment for associated cerebral anomalies.