Callosal anomalies with interhemispheric cyst: Expanding the phenotype

Aim: To determine the frequency and clinical features of corpus callosum hypoagenesis, dysgenesis or hypoplasia in conjunction with extraparenchymal interhemispheric cyst. Methods: A retrospective study of clinical files and imaging records of all 2500 children referred to the University Department of Paediatrics, Catania, Italy, who underwent neuroimaging by ultrasound, computerized tomography or magnetic resonance imaging in 1992 - 2003. Five children ( all girls, aged 2 - 18 y) were found to have abnormalities of the corpus callosum associated with interhemispheric cyst. Results: Three cases were type 2b, one type 2c and one mixed type 2b and 2c according to the classification proposed by Barkovich et al. The onset of clinical symptoms was very early, with severe neurological involvement, seizures that were difficult to treat and profound psychomotor retardation. Conclusions: In callosal anomalies with cysts, a prevalence in females is not confined to type 2b cysts, the spectrum of abnormalities of the corpus callosum is more varied than previously recorded, and the natural history and outcome of the condition are poor with profound developmental delay and drug-resistant seizures. The finding that all the cases were of type 2 suggests that the overall phenotype is more widespread than previously thought and may present in association with other complex syndromes.