Septopreoptic Holoprosencephaly: A Mild Subtype Associated with Midline Craniofacial Anomalies

Department of Neurology, Medical Center, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5235, USA.
American Journal of Neuroradiology (Impact Factor: 3.68). 10/2010; 31(9):1596-601. DOI: 10.3174/ajnr.A2123
Source: PubMed

ABSTRACT SUMMARY: HPE is a congenital brain malformation characterized by failure of the prosencephalon to divide into 2 hemispheres. We have identified 7 patients who have a mild subtype of HPE in which the midline fusion was restricted to the septal region or preoptic region of the telencephalon. This subtype, which we call septopreoptic HPE, falls in the spectrum of lobar HPE, but lacks significant frontal neocortical fusion seen in lobar HPE. Other imaging characteristics include thickened or dysplastic fornix, absent or hypoplastic anterior CC, and single unpaired ACA. The SP was fully formed in 4, partially formed in 2, and absent in 1. Mild midline craniofacial malformation, such as SMMCI and CNPAS were found in 86% and 71%, respectively. Patients outside of infancy often manifested language delay, learning disabilities, or behavioral disturbances, while motor function was relatively spared.

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    ABSTRACT: Introduction The circle of Willis is a large arterial anastomotic ring present at the basal cistern of the brain, uniting the internal carotid and the vertebrobasilar system. Branches from this arterial ring are distributed to supply the brain. In the year 1664, Sir Thomas Willis was the first to describe the importance of the circle in maintaining collateral flow. It was observed that there is very little mixing of blood between the collateral branches of the circle. These collaterals may however open up during occlusive episodes of the proximal feeding vessels. The anatomy of the circle is known to vary considerably and functionally a complete circle is a rare finding. This type of incomplete or variant forms off the circle may diminish its role as a collateral route. Methods The morphological pattern of circle of Willis of 70 healthy individuals from northeast India was studied retrospectively using Time of Flight-Magnetic resonance angiography (TOF-MRA). Results Only 17 (24.28%) MRA's presented with a complete (classic) circle of Willis. Most common variant observed in our study was unilateral hypoplastic posterior communicating artery (20%). Most common variant observed in the anterior circulation was unilateral hypoplastic A1 segment of anterior cerebral artery (11.42%). Discussion Most of the variant forms observed were comparable with earlier established findings. This variability (rare patterns) can be distinguished from an anomalous architecture if correlated phylogenically and embryologically.
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    ABSTRACT: Holoprosencephaly (HPE) is the most common developmental defect of the forebrain characterized by inadequate or absent midline division of the forebrain into cerebral hemispheres, with concomitant midline facial defects in the majority of cases. Understanding the pathogenesis of HPE requires knowledge of the relationship between the developing brain and the facial structures during embryogenesis. A number of signaling pathways control and coordinate the development of the brain and face, including Sonic hedgehog, Bone morphogenetic protein, Fibroblast growth factor, and Nodal signaling. Mutations in these pathways have been identified in animal models of HPE and human patients. Because of incomplete penetrance and variable expressivity of HPE, patients carrying defined mutations may not manifest the disease at all, or have a spectrum of defects. It is currently unknown what drives manifestation of HPE in genetically at-risk individuals, but it has been speculated that other gene mutations and environmental factors may combine as cumulative insults. HPE can be diagnosed in utero by a high-resolution prenatal ultrasound or a fetal magnetic resonance imaging, sometimes in combination with molecular testing from chorionic villi or amniotic fluid sampling. Currently, there are no effective preventive methods for HPE. Better understanding of the mechanisms of gene–environment interactions in HPE would provide avenues for such interventions.For further resources related to this article, please visit the WIREs website.Conflict of interest: The authors have declared no conflicts of interest for this article.
    01/2015; 4(1). DOI:10.1002/wdev.161
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