TY - CHAP M1 - Book, Section TI - Hydrocephalus A1 - Bianchi, Diana W. A1 - Crombleholme, Timothy M. A1 - D'Alton, Mary E. A1 - Malone, Fergal D. Y1 - 2015 N1 - T2 - Fetology: Diagnosis and Management of the Fetal Patient, 2e AB - Key PointsHydrocephalus is usually due to obstruction of CSF flow, either within (noncommunicating hydrocephalus) or outside (communicating hydrocephalus) the ventricles.Ventriculomegaly simply refers to enlargement of intracranial ventricles. It can be associated with hydrocephalus or abnormal brain development.Ventriculomegaly is commonly defined as a measurement of 10 mm or greater in the posterior horns of the lateral ventricles noted on an axial brain scan, irrespective of gestational age.Approximately 40% of cases of ventriculomegaly have associated CNS or extra-CNS abnormalities, and 12% have an abnormal karyotype.Underlying causes include aqueductal stenosis, meningomyelocele, intrauterine infection (CMV, toxoplasmosis, syphilis), agenesis of corpus callosum, X-linked hydrocephalus syndromes, intracranial hemorrhage, Dandy–Walker malformation, and intracranial tumors.L1CAM gene mutations account for up to 25% of male cases of isolated congenital hydrocephalus.Recurrence risk, in the absence of a positive family history, or a known L1CAM mutation, is approximately 4%. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/11/05 UR - obgyn.mhmedical.com/content.aspx?aid=1106396532 ER -