Holoprosencephaly in neurosurgical practice.

The clinical, angiographic, and pneumoencephalographic features of seven cases with holoprosencephaly are reported. Three of the alobar type in this series revealed the facial dysmorphia characteristic of the anomaly. In the other four cases (one alobar, one semilobar, and two lobar), such facial anomaly was absent, and the diagnosis was achieved only after contrast studies. An azygous anterior cerebral artery running over the cerebral surface due to a defective interhemispheric fissure is pathognomonic for alobar and semilobar holoprosencephaly. Dysgenesis of the deep venous system was found in alobar, semilobar, and lobar holoprosencephaly, a finding helpful in diagnosis, especially of the lobar type. Air study and computerized tomography scan revealed incomplete separation of the ventricular system. The basic nature of holoprosencephalization and its differentiation from non-holoprosencephalic malformation are discussed. Six of the seven patients reported had hydrocephalus.