Neural tube defects pdf

The importance of this condition has generated a large body of literature that seldom was written for the clinician in a comprehensive and didactic manner. In this book, each chapter is richly illustrated and dedicated to one disease with subheadings that encompass etiology, molecular biology, clinical anatomy, symptoms, rationale for surgical procedures, natural history and transition into adulthood. Get BOOK. Author : Jorge A. Section Navigation.

Facebook Twitter LinkedIn Syndicate. Facts about Neural Tube Defects. Minus Related Pages. Neural tube defects are severe birth defects of the brain and spine. Links with this icon indicate that you are leaving the CDC website. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.

In addition, in this chapter, we discuss anomalies occurring secondarily to open or closed neural tube defects, such as tethered cords, the Chiari II malformation, and hydrocephalus, as well as other major anomalies of the neural tube, such as holoprosencephaly and lissencephaly.

Ideally, the classification of congenital malformations of the brain and spinal cord would be based on the cause of abnormal- ity. However, as stated earlier, the causes of such defects are not known in many cases.

Therefore, in this chapter, we classify neural tube defects based on their anatomical features. More exhaustive coverage of neural tube defects appears elsewhere 2,3. From: Methods in Molecular Biology, Vol. II Edited by: R. Tuan and C. Our classification scheme is as follows: A. Open neural tube defects 1. Anencephaly 2. Spinal rachischisis a. Myeloschisis b. Myelomeningoceles meningoceles 3. Iniencephaly 4. Encephaloceles B. Closed neural tube defects 1.

Spina bifida occulta 2. Lipomas and lipomeningoceles 3. Split cords diastematomyelia, diplomyelia 4. Neurenteric cysts 5. Dermal sinuses 6. Sacral agenesis caudal regression Each of these neural tube defects will now be defined briefly. Classification of Neural Tube Defects 2.

Open Neural Tube Defects 2. Anencephaly Failure of the cephalic part of the neural tube to close results in a condition called exencephaly. Because the malformed brain tissue is exposed on the surface of the body and is not covered by skin, the vault i. During subsequent gestation, the exposed brain tissue degenerates, resulting in anen- cephaly literally, absence of the brain. Spinal Rachischisis Spina Bifida Operta Failure of the neural tube to close in the spinal cord region results in spinal rachis- chisis literally, cleft spine.

The term spina bifida aperta refers to the fact that the spines of the vertebrae are bifid. Thus, spinal rachischisis involves defects both of soft tissues i. There are two main types of spinal rachischisis: 1. Myeloschisis: The neural tube at the site of the defect is broadly open and the central canal is absent. This is the most deleterious type of neural tube defect. Myeloschisis commonly occurs at the thoracolumbar junction.

Myelomeningoceles: A central canal forms, although it may be open on its dorsal surface. The membranous coverings i.

Myelomeningoceles tend to occur in the lum- bar and sacral regions. Rarely, another malformation occurs at the spinal cord level in which the membranous coverings of the spinal cord protrude through the defect in the skin, but the spinal cord does not; this defect is called a meningocele.

In meningoceles, the spinal cord can still be abnormal, but the abnormality is usually less severe than in myelomeningoceles. Iniencephaly Iniencephaly is a defect in which the occipital bone is deficient and the brain is exposed. Iniencephaly differs from anencephaly in that it is asso- ciated with the formation of the cranial vault and spinal retroflexion. If the hernia contains both brain tissue and meninges, the defect would best be described by the term encephalomeningocele.

However, the term encepha- locele has been used traditionally by clinicians to describe this defect, and this tradition continues today. If the hernia contains only meninges, it is called a cranial meningocele.