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Neurology

Holoprosencephaly

credit for this information goes to Neurology Channel

The face and forebrain (or prosencephalon) of an embryo normally begin to develop in the 5th and 6th weeks of pregnancy. If the forebrain fails to divide into normal right and left hemispheres, deformities in the face and brain, or holoprosencephaly, results.

Types
The most serious form is alobar holoprosencephaly, in which the hemispheres completely fail to separate. It is characterized by severe facial and brain abnormalities so profound that they often cause intrauterine death. In semilobar holoprosencephaly the brain's hemispheres develop only a slight separation. Lobar holoprosencephaly is marked by substantial, but still incomplete, separation of the hemispheres.

Causes
The cause of most cases of Holoprosencephaly is unknown. Nearly half of all cases are linked to chromosomal factors, such as Patau's syndrome (trisomy 13) and Edwards' syndrome (trisomy 18). There appears to be an increased risk for Holoprosencephaly in infants of diabetic mothers, but the significance of this is not well understood.

Signs and Symptoms
The most severe forms of Holoprosencephaly produce seizures and mental retardation. Typical facial defects involve the eyes, nose, and upper lip. In some cases, the nose may be missing entirely or may develop above the eye in the form of a proboscis, a tubular appendage. Other facial anomalies include:

Ethmocephaly (rare): absent nose; a proboscis separates narrow-set, sometimes abnormally small, eyes

Cebocephaly: small, flattened nose with a single nostril beneath incomplete or underdeveloped narrow-set eyes

Premaxillary agenesis median (cleft lip)

Cyclopia: single eye located in the area normally occupied by the root of the nose

Treatment
Treatment is largely symptomatic.

Prognosis
Infants born with most forms of Holoprosencephaly face a poor prognosis. Few who survive achieve significant mental development.

Support and additional information

Families for Hope,Inc.

 The Cerebral Palsy Network©1997/2014. All graphics are the exclusive property of CPN, unless otherwise indicated. Contact Cerebral Palsy Network   for further information. Last updated 05/04/14