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

There have been reports of sporadic cases of holoprosencephaly recognized by MRI. This is a pathology with precocious origin (during the organogenesis of the brain, that originates from a cleavage failure of the primitive prosencephalon. Its incidence is of around 1 out of 10.000 births (Sanders, 1996). According to its level of severity, holoprosencephaly is classified in alobar, semilobar and lobar (Table 1). Despite few accounts in literature, MRI does seem to be beneficial to characterizing an intrauterine lobar holoprosencephaly, enabling a more precise differential evaluation with agenesis of the corpus callosum and Dandy-Walker deformity (Girard, 1993; Lair-Milar, 1997).

Fetuses with holoprosencephaly of both the alobar and semilobar types tend to die at birth. Survival relates to the most mild forms of the disorder, including the lobar type, and is associated with mental retardation.