Category:Definition Of HPE
From Holoprosencephaly
What is Holoprosencephaly?
Holoprosencephaly (HPE) is a congenital anomaly in which there is incomplete development of the brain. In utero, the developing forebrain (prosencephalon) fails to divide into two separate hemispheres and ventricles. Specifically, there is incomplete cleavage into right and left hemispheres; into the telencephalon and diencephalons; and into the olfactory and optic bulbs and tracts. Based on the level of cleavage, Holoprosencephaly is classified into 4 subtypes: Alobar, Semilobar, Lobar and MIHV.
This disorder consists of a spectrum of defects, malformations and associated abnormalities. Disability is based upon the degree in which the brain is affected. Moderate to severe defects may cause mental retardation, spastic quadriparesis, atheoid movements, endocrine disorders, epilepsy and other serious conditions. Whereas, mild brain defects may only cause learning or behavior problems with few motor impairments.
Prenatal Diagnosis of Holoprosencephaly
Prenatal detection of Holoprosencephaly (HPE) is possible by targeted ultrasound examination. Severe cases of HPE can often be detected on prenatal ultrasonography at approximately 16 weeks’ gestation, although less severe forms may not be reliably detected.
A prenatal history should be obtained to determine if any teratogen exposure occurred. A karyotype for chromosome analysis should be obtained.
Diagnosis of Holoprosencephaly at Birth
Facial features characteristic for Holoprosencephaly (HPE) may suggest the diagnosis in the newborn period. Ultrasound of the head may be used for initial diagnosis. CT or MRI of the brain can confirm the diagnosis.
Diagnosis of Holoprosencephaly in Infant/Childhood
If the child shows developmental delays, an MRI may be requested by the pediatrician. Only MRI or CT scans can confirm the diagnosis.
Click here to read about: New Diagnosis of Holoprosencephaly
Click here to read what specialists have to say about caring for children with Holoprosencephaly: Doctor Q&A
Types of Holoprosencephaly
Holoprosencephaly can range from mild to severe and is classified into four types:
- Alobar Holoprosencephaly (severe)--where the brain is not divided and there are severe abnormalities (there is an absence of the interhemispheric fissure, a single primitive ventricle, fused thalami, and absent third ventricle, olfactory bulbs and tracts and optic tracts).
- Semi-Lobar Holoprosencephaly (moderate)--where the brain is partially divided and there are some moderate abnormalities; where there are two hemispheres in the rear but not the front of the brain (there are partially separated cerebral hemispheres and a single ventricular cavity).
- Lobar Holoprosencephaly (mild)--where the brain is divided and there are some mild abnormalities (there is a well developed interhemispheric fissure however there is some fusion of structures).
- Middle Interhemispheric Variant of Holoprosencephaly (MIHV) -- where the middle of the brain (posterior frontal and parietal lobes) are not well separated.
