Semilobar Holoprosencephaly - A Rare Cephalic Disorder

Holoprosencephaly (HPE) is a rare cephalic disorder resulting from incomplete or absent cleavage of the forebrain into distinct cerebral hemispheres.It comprises of a spectrum of malformations affecting the forebrain, usually accompanied by facial anomalies.Semilobar HPE includes structural anomalies of intermediate severity.A preterm male baby at 28 weeks of gestation was still born to a 26 year old woman.Prenatal ultrasonography suggested semilobar HPE.On examination, the baby had microcephaly and midline facial defects.Spina bifida occulta and imperforate anus were also present.On dissection of the brain, the cerebral hemispheres were fused across the midline except in the occipital region.Section across the forebrain revealed a monoventricle, fused thalami and absent corpus callosum.The etiology of HPE is heterogenous.Early antenatal diagnosis is crucial, 3D ultrasonography being the investigation of choice.