Neurodevelopmental outcome after antenatal diagnosis of posterior fossa abnormalities

Posterior fossa abnormalities are sonographically diagnosable in the fetus. Anomalies of this region include Dandy-Walker malformation, enlarged ciste rns magna, and arachnoid cyst. Despite prenatal diagnosis, the uncertaintie s related to natural history and neurodevelopmental outcome in survivors ma ke patient counseling difficult. The purposes of this study were to determi ne the accuracy of prenatal diagnosis of these lesions and elucidate long-t erm neurodevelopmental outcome in survivors in prenatally diagnosed posteri or fossa abnormalities. Fifteen cases of posterior fossa abnormalities were reviewed. Antenatal diagnoses of Dandy-Walker malformation was made in 13 of these cases, arachnoid cyst in one case, and enlarged cisterna magna in one case. Hydrocephalus was present in 66% of patients. The sonographic dia gnosis was concordant with the pathologic or neonatal radiologic diagnosis in 13 of 15 cases. Seven fetuses (47%) exhibited additional cranial or extracranial anomalies. A karyotypic abnormality (trisomy 18) was found in one of 15 cases of post erior fossa abnormalities. Neurodevelopmental delay was present in 80% of s urvivors with follow-up study to 4 years of age. Prenatal diagnosis of post erior fossa abnormalities is highly accurate, yet the differential diagnosi s can be challenging. Cognitive and psychomotor developmental delays remain commonplace despite early diagnosis and treatment. The approach with famil ies in cases of prenatal diagnosis of posterior fossa abnormalities should include a search for additional central nervous system and extra-central ne rvous system anomalies in the fetus and counseling of parents regarding pot ential adverse outcome for survivors.