Objective: This study aimed to measure the changes in the posterior brain in fetuses with Dandy-Walker malformation (DWM) with complete agenesis of the cerebellar vermis between 11(+0) and 13(+6) weeks of gestation.
Methods: In the midsagittal view, the brain stem (BS) diameter and the brain stem to occipital bone (BSOB) diameter were measured, and the BS/BSOB ratio was calculated in four fetuses with confirmed DWM and 40 normal fetuses. Delta values corrected for CRL were compared between both groups.
Results: In contrast to the normal controls, in fetuses with DWM at 11(+0) to 13(+6) weeks of gestation, the border between the fourth ventricle and the cisterna magna was not visible. There were no significant differences in the BS diameter between the two groups (p<0.3). In the DWM group, the mean diameter of the BSOB was found to be significantly higher than in the controls (p=0.0011), and it was above the 95th centile in all four cases. In addition, the BS/BSOB ratio was significantly decreased in fetuses with DWM (p=0.0011).
Conclusions: At 11-13 weeks, fetuses with DWM have measurable abnormalities in the posterior brain. An abnormal appearance of the fourth ventricle-cisterna magna complex was present in all four cases of DWM.
© 2012 John Wiley & Sons, Ltd.