Disorders of prosencephalic development

Abstract

Abnormal ventral induction may result in disorders of formation, cleavage, and midline development of prosencephalic structures. Holoprosencephaly is a developmental field defect of impaired cleavage of prosencephalon. The most widely accepted classification of holoprosencephaly recognizes three major varieties: the alobar, semilobar and lobar types, according to the severity of the malformation. The brain malformations, characterized by the fusion of the cerebral hemisphere along the midline are commonly associated with facial anomalies.Corpus callosum agenesis and septo-optic dysplasia are disorders of prosencephalic midline development, and usually have less severe presentations but still, affected subjects may suffer from neurodevelopmental retardation, and/or endocrinologic and visual disorders.In this article we report an up-to-date of pathogenesis, prenatal sonographic findings, differential diagnosis and prognosis of the aforementioned anomalies.

Prenatal diagnosis and outcome of partial agenesis and hypoplasia of the corpus callosum

“…An association with interhemispheric arachnoid cyst, holoprosencephaly, asymmetric ventriculomegaly and migration disorders is reported 19,20 . Prenatal diagnosis of fetal callosal underdevelopment remains a difficult task with only few cases of partial agenesis reported in the literature 10,11,20,21 . In fetuses with partial callosal agenesis a shorter corpus callosum may be demonstrated at ultrasound or MRI and eventually confirmed at pathology (Figures 2 and 3).…”

Malformations of cortical development with good clinical outcome: a case report and review of literature

“…Although optic nerve malformation is a well-known complication of partial defect of septum pellucidum,2 a dilated fundus examination and visual field screening test were normal and his visual acuity was 20/40 bilaterally. The patient was able to communicate in simple phrases.…”

Ultrasound Diagnosis of Congenital Brain Anomalies

“…Development the corpus callosum occurs at the same time as cerebral and cerebellar development, and therefore agenesis of the corpus callosum is associated with other brain anomalies in 80% of cases. Associated CNS anomalies may include midline intracerebral lipomas, encephalocele, interhemispheric arachnoid cyst, microcephaly, Dandy-Walker malformation, Arnold-Chiari malformation, holoprosencephaly, hydrocephalus, disorders of neuronal migration, such as neuronal heterotopias, lissencephaly, pachygyria, and schizencephaly (Hetts et al, 2006;Volpe, 2009). With partial agenesis (hypogenesis), the anterior portion (posterior genu and anterior body) is formed, but the posterior portion (posterior body and splenium) is not.…”