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State of the Art Cranial Ultrasound Imaging in Neonates
Published on: February 2, 2015
Holoprosencephaly: a survey of the entity, with embryology and fetal imaging
Thomas C Winter1, Anne M Kennedy, Paula J Woodward
1From the Abdominal Imaging Section, Department of Diagnostic Radiology, University of Utah Medical Center, 30 N 1900 E, Room 1A071, University Hospital, Salt Lake City, UT 84132-2140.
Insights
Holoprosencephaly (HPE) is a severe brain malformation affecting fetal development. This review details HPE spectrum findings, associated anomalies, and outcomes for improved diagnosis and counseling.
Area of Science:
- Developmental Biology
- Neuroscience
- Medical Imaging
Background:
- Structural brain malformations cause significant childhood mortality and morbidity.
- Holoprosencephaly (HPE) is a severe congenital brain malformation due to abnormal prosencephalon cleavage.
- The HPE spectrum includes alobar, semilobar, lobar forms, and variants like middle interhemispheric variant (MIH).
Purpose of the Study:
- To review the spectrum of fetal findings in Holoprosencephaly (HPE).
- To discuss brain embryology, HPE imaging characteristics, epidemiology, and associated anomalies.
- To summarize outcomes for surviving children and aid parental counseling.
Main Methods:
- Review of fetal ultrasonography and magnetic resonance imaging.
- Correlation with clinical, autopsy, and postnatal imaging data.
- Synthesis of existing literature on HPE embryology, imaging, and outcomes.
Main Results:
- HPE spectrum findings range from severe brain malformations to subtle forms.
- Facial anomalies are common and can predict brain involvement.
- Prognosis varies; milder forms may allow survival into adolescence with significant developmental delays.
Conclusions:
- Accurate recognition of HPE spectrum findings in fetuses is crucial.
- Understanding associated anomalies and prognosis aids in parental counseling.
- Fetal imaging plays a key role in diagnosing and managing HPE.
Abstract:
Structural malformations of the brain are an important cause of childhood mortality and morbidity, with the latter having long-term financial and psychosocial implications for the affected child and family. Holoprosencephaly (HPE) is a severe brain malformation characterized by abnormal cleavage of the prosencephalon in the 5th gestational week. Aprosencephaly and atelencephaly occur earlier because of failure in the formation of the prosencephalon and telencephalon, respectively. The HPE holoprosencephaly spectrum classically includes alobar, semilobar, and lobar forms, although there are no clear-cut defining features. The middle interhemispheric variant (MIH), also known as syntelencephaly, is classified as a variant of HPE holoprosencephaly with midline interhemispheric fusion. Other conditions sometimes included in the spectrum of HPE holoprosencephaly include septo-optic dysplasia (SOD); "minimal" HPE holoprosencephaly , which is associated with subtle craniofacial malformations and mild developmental delay; and microform HPE holoprosencephaly , which by definition excludes brain involvement. The focus of this article will be on the spectrum of findings visible in fetal manifestation of the HPE holoprosencephaly spectrum. Brain embryology; the imaging characteristics, epidemiology, and embryology of HPE; and the more common associated anomalies, particularly those of the face ("the face predicts the brain") are reviewed. Recognition of these anomalies is important for accurate parental counseling, since the prognosis is poor but not invariably lethal; children with the milder forms may live well into their teens with severe developmental delays, endocrine dysfunction, and disrupted homeostasis. Available data on outcome in surviving children are summarized. Illustrative fetal ultrasonographic and magnetic resonance images are presented with clinical, autopsy, and postnatal imaging correlation.
