Presentation
Macrocephaly.
Patient Data
large monoventricle communicating posteriorly with dorsal cyst, exerting compression upon both cerebellar hemispheres, with subsequent tonsillar herniation below the foramen magnum
absent midline structures, including the corpus callosum, septum pellucidum, and falx cerebri
fused thalami
the remaining part of the cerebral cortex is compressed anteriorly and laterally by the large monoventricle
Case Discussion
Holoprosencephaly is a congenital brain malformation that results from the failure of the division of the prosencephalon into two distinct cerebral hemispheres. Alobar holoprosencephaly should be differentiated from severe hydrocephalus, hydranencephaly, and Dandy-Walker malformation. Severe hydrocephalus is characterised by preserved falx cerebri and distinct lateral ventricles. In hydranencephaly, the thalami are not fused. Both Dandy-Walker malformation and hydranencephaly show preserved falx cerebri, inter-hemispheric fissure, corpus callosum, and third ventricle.