Objective: To determine the frequency of isolated mega cisterna magna (MCM) in Saudi population, compare the accuracy of fetal ultrasound with postnatal neuro-imaging, report the associated central nervous system (CNS) anomalies on postnatal neuro-imaging.
Study Design: Retrospective study.
Place and Duration of Study: King Fahad Armed Forces Hospital Jeddah Saudi Arabia from Jan 2007 to July 2011.
Material and Methods: This was a retrospective study conducted at King Fahad Arrmed Forces Hospital Jeddah, Saudi Arabia. We included all reported cases of fetal mega cisterna magna from January 2007 till July 2011. Ante-natal and postnatal records and neuro-imaging studies of all the cases were reviewed and documented on the database. Neurological assessment was done by Pediatric Neurology Consultant at an average age of 8 months of life.
Results: MCM was diagnosed in 26 (0.12%) on fetal scans (15 male and 11 females). Post natal scans were available for 20/26 (77%) and 6/26 (23%) cases were missing. Of the 20 post natal scans, 12 (60%) scans were normal and 8 (40%) scans were abnormal. The following abnormalities were detected: 3 (37.5%) cerebellar hypoplasia, 2 (25%) partial dysgenesis of corpus callosum, 2 (25%) cases were confirmed as MCM and 1 (12.5%) arachnoid cyst. Neuro-developmental assessment was reported as normal in 50% of the cases with associated CNS anomalies.
Conclusion: The association of MCM with major CNS anomalies is significant in this study population. Post natal neuro-imaging confirmation is required for all fetuses with mega cisterna magna on fetal sonography.
Head ultrasound, Mega cisterna magna, MRI brain.