OC72: Prenatal diagnosis of cerebellar anomalies by dedicated neurosonography

To describe the spectrum of cerebellar anomalies diagnosed at FNC between 1999 and 2007. We retrospectively reviewed 129 cases of suspected cerebellar anomalies referred to our institution. All patients underwent a detailed ultrasonographic anatomical survey followed by dedicated neurosonographic examination. The gestational age at the time of the first examination was 26 weeks 5 days (range, 12 weeks 5 days–37 weeks 6 days). Ultrasound was complemented by MRI in 76 patients. The initial examination was considered normal in 36 fetuses; in this group, we observed a minimal upward rotation of the vermis in seven. One of these patients was diagnosed as suffering from molar tooth sign syndrome shortly after birth. The vermis was not clearly visualized in three patients. Mega cisterna magna was found in 27 fetuses and arachnoid cysts in six; all these patients but one were delivered; one patient developed obstructive hydrocephalus necessitating cyst fenestration; another patient suffered from moderate psychomotor retardation. Classical DWM was diagnosed in 11 patients, vermian dysgenesis in 15 and vermian agenesis in two. Anomalies involving the entire cerebellum were diagnosed in 16: hypoplasia (10), dysgenesis (six). Miscellaneous findings were noted in the remaining 13 patients. Associated brain anomalies were found in 42 patients and non-CNS anomalies in 26. Dedicated neurosonography remains the main tool in prenatal diagnosis of cerebellar anomalies. With adequate knowledge of the cerebellar anatomy and the spectrum of possible pathologies, accurate diagnosis is possible in the majority of cases.