Cranial Anomalies/Defects
These abnormalities range from major defects that are incompatible with life to those that are minor and insignificant. With large defects, there is often herniation of the meninges and/or brain:
Acrania: This is the absent of the calvaria and extensive defects of the vertebral column are often present. It is associated with anencephaly (partial absence of the brain). Anencephaly (meroencephaly) (fig. 21A) results from failure of the cranial end of the neural tube to close during the fourth week of development.
Craniosynostosis: This is a condition cause by prenatal premature closure of the cranial sutures and this result in the most severe abnormalities.
The shape of the skull depends on which of the sutures closed prematurely.
Cranioschisis: Is the failure of the cranial vault to form usually due to failure of the cranial neuropore to close. The brain tissue degenerates as a result of its exposure to amniotic fluid resulting in anencephaly.
These abnormalities range from major defects that are incompatible with life to those that are minor and insignificant. With large defects, there is often herniation of the meninges and/or brain:
Acrania: This is the absent of the calvaria and extensive defects of the vertebral column are often present. It is associated with anencephaly (partial absence of the brain). Anencephaly (meroencephaly) (fig. 21A) results from failure of the cranial end of the neural tube to close during the fourth week of development.
Craniosynostosis: This is a condition cause by prenatal premature closure of the cranial sutures and this result in the most severe abnormalities.
The shape of the skull depends on which of the sutures closed prematurely.
- Scaphocephaly: Is due early closure of the sagittal suture which results in frontal and occipital expansion and the skull become long and narrow
- Brachycephaly: Is due to premature closure of the coronal suture and results in a short, high skull
- Plagiocephaly: Is due to prenatal closure of the coronal and lambdoid sutures on one side only, and results to asymmetric craniosynotosis (fig. 21C)
- Trigonocephaly: Is due to premature closure of the frontal (metopic) suture and this result in a deformity of the frontal bone and other anomalies.
Cranioschisis: Is the failure of the cranial vault to form usually due to failure of the cranial neuropore to close. The brain tissue degenerates as a result of its exposure to amniotic fluid resulting in anencephaly.
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(Copyright © 2011 by U. Bala)