Semilobar holoprosencephaly

Case contributed by Mohammad A. ElBeialy
Diagnosis almost certain


Newborn female baby with poor feeding and abnormal facies, cleft lip and hypotelorism.

Patient Data

Age: 13 days
Gender: Female
  • partial cleavage of the cerebral hemispheres with fusion across the frontal lobes

  • monoventricle with partial occipital and temporal horns of the lateral ventricles

  • partially fused thalami which are abnormally rotated and anteriorly situated with consequently small sized 3rd ventricle

  • absence of septum pellucidum

  • rudimentary falx cerebri and interhemispheric fissure which is formed caudally with cleavage and separation of the occipital lobes

  • hypoplasia of the corpus callosum

Case Discussion

Semilobar holoprosencephaly is an intermediate form of holoprosencephaly with partial cleavage of the prosencephalon. 

Absent septum pellucidum is present in all types of prosencephaly and the presence of septum pellucidum virtually excludes holoprosencephaly. 

Alobar holoprosencephaly is non-cleavage of the cerebral hemispheres with single monoventricle (crescentic-shaped holoventricle), dorsal cyst widely communicating with the single monoventricle, horse-shoe configuration of the cerebral mantle, fused thalami & absence of the corpus callosum, falx cerberi, interhemispheric fissure, optic tracts and olfactory bulbs as well as absent 3rd ventricle, internal cerebral veins, vein of Galen, straight sagittal sinus and Sylvian fissures.

Lobar holoprosencephaly is just rostral or anteroinferior fusion of the cerebral hemispheres & the absence of the septum pellucidum is the clue for diagnosis. The differential diagnosis is septooptic dysplasia or De-Morsie syndrome.  

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