Non-visualization of the cavum septi pellucidi is not synonymous with agenesis of the corpus callosum

Objectives: To describe a cohort of fetuses with non-visualization of the cavum septi pellucidi (CSP) without callosal agenesis and to assess the significance of this finding with respect to postnatal development.

Methods: We reviewed the files of all patients referred because of suspected fetal supratentorial midline anomalies, and identified those fetuses with a diagnosis of non-visualization or obliteration of the CSP.

Results: From an initial cohort of 114 patients we identified 23 cases. Mean ( ± SD) gestational age at referral was 24.5 ± 1.3 weeks; referral diagnoses (with more than one in some cases) included: non-visualization or an echogenic CSP (n = 18), suspected callosal anomaly (n = 5), other findings (n = 5). The fetuses were examined for the first time at the Fetal Neurology Clinic at a mean gestational age of 26.6 ± 3.1 weeks (range, 22-34 weeks; median, 27 weeks). In all of the fetuses the zone where fluid should have been observed was echogenic. In 17 fetuses this was an apparently isolated finding and in six it was associated with other findings, but only one fetus had associated malformations. Follow-up was available for 16 children at a mean age of 17.4 months (range, 4-36 months; median, 19.5 months). Normal development was reported in 14 children. One child had infantile hypotonia but normal developmental milestones and another had mild motor delay and language delay. These two children did not have associated anomalies at the prenatal scan.

Conclusion: Non-visualization of the CSP is not always associated with agenesis of the corpus callosum. When isolated it may be considered a variation of normal development.