Heron Werner, MD & Pedro Daltro, MD
Clínica de Diagnóstico por Imagem (CDPI) & Instituto Fernandes Figueira (IFF) – FIOCRUZRio de Janeiro – Brazil

Dorothy I. Bulas M.D.
Professor of Radiology and Pediatrics
Children's National Medical Center
George Washington University Medical Center
111 Michigan Ave, NW,   Washington D.C. 20010

Hydranencephaly is the complete or nearly complete destruction of the cerebral cortex and basal ganglia. Despite the absence of the cerebral hemispheres, there is the presence of the brain stem, thalamus and cerebellum. The falx cerebri is smaller in size, absent at times, with large amounts of fluid above the non-fused thalami and cerebellum. The differential diagnosis is given through the big hydrocephaly as well as the alobar and semilobar holoprosencephaly. The etiology is heterogeneous, resulting probably form the intrauterine destruction of the cerebral parenchyma that originates in vascular alterations (total and bilateral obstruction of the internal carotid artery) or in infectious alterations (cytomegalovirus, toxoplasmosis).