Home > Diagnoses & Conditions > Neural Tube Defects > Description
Neural Tube Defects - Description
ICD-9
741, Spina bifida
See NTD ICD9
(
71 KB)
for a complete list of codes associated with neural tube defects.
Description
Neural tube defects (NTD), including spina bifida, comprise a group of conditions in which there has been improper development of the spine during embryonic development, at about the end of the first month of gestation. The entire human nervous system develops from a plate of specialized cells that form along the back of the embryo. The edges of this elongated plate curl toward each other, joining in as many as four places to form a tube and then proceeding caudally (tailward), where the end of the spinal cord will form, and cephalad (toward the head), where further specialization will lead to brain development. Spina bifida results from problems during this amazingly complex process and genetic and environmental factors are involved. [Kaufman: 2004] [Finnell: 2003] Defects can be classified as open (spina bifida, encephalocele) or closed (spina bifida occulta, diastematomyelia). Types of NTD include:- myelomeningocele: The most common symptomatic form of NTD and the most severe. The spinal cord and the meninges protrude through the posterior openings in the vertebrae. See the Myelomeningocele Illustration (MedlinePlus)
- meningocele: The meninges protrude through the posterior openings in the vertebrae, but the spinal cord is not involved.
- encephalocele: The meninges or brain tissue protrude through the skull
- anencephaly: The cephalic end of the neural tube fails to close, resulting in the absence of a major portion of the brain, skull, and scalp. Anencephaly is not compatible with life; infants born with anencephaly, on average, live only a few hours.
- spina bifida occulta: There is an opening or defect in one or more vertebrae with no pathology in the spinal cord. This is generally asymptomatic
- closed neural tube defects: This comprises a diverse group of defects where the spinal cord is malformed, but the vertebral column is intact. These include lumbosacral lipomas and diastematomyelia. These defects may have clinical presentations ranging from mild to very severe. Infants with these defects may be asymptomatic at birth and then develop symptoms over time. Midline sacral skin tags, hairy patches, hemangiomata and other cutaneous markers may signal the presence of a closed neural tube defect and should be looked for in all newborns [Brand: 2007]
- Abnormal spinal cord development results in some degree of paralysis, or muscle weakness, and sensory loss below the level of the defect. The neurologic lesions are complicated and unique for each child. The paralysis is most likely to be a flaccid paralysis, although tethered cord and other accompanying defects may lead to lower extremity spasticity
- Bowel and bladder dysfunction are almost universal, even in low sacral lesions
- Hydrocephalus and abnormal brain development - most children with myelomeningocele also have hydrocephalus (70-90%) and may need a shunt to relieve the fluid pressure in the brain (see Neurosurgical issues in children with spina bifida (general)). Children with myelomeningocele may also have abnormal brain development (Chiari II, thinning of the corpus callosum, with decreased neuron content in the posterior region of the brain)
- Neurogenic bladder - Because the bladders of children with myelomeningocele are paralyzed (neurogenic), reflux of urine up the ureters and into the kidneys (vesico-ureteral reflux) can occur. This can lead to kidney failure, particularly in the setting of frequent urinary tract infections
- Mobility problems
- Latex allergy
- Skin breakdown
- Constipation and other gastrointestinal problems
- Orthopedic problems
- Learning and mood problems
While 90% of neural tube defects occur without a personal or family history of NTDs, the CDC has identified some risk factors:
- A previous NTD-affected pregnancy
- Maternal folic acid deficiency (see Folic acid supplementation in NTD)
- Maternal insulin-dependent diabetes
- Use of certain anti-seizure/mood stabilizing medications (valproic acid and carbamazepine) during pregnancy
- Medically diagnosed obesity in the mother
- Exposure to high temperature in early pregnancy (prolonged fever or hot tub use)
- Maternal race/ethnicity (more common among white women than black and more common in Hispanic women than non- Hispanic women)
- Lower maternal socio-economic status
Genetics
Because genetic factors may be involved, families who have a child with a NTD should be referred to genetic counseling if they are considering having another child. [Deak: 2008] Environmental influences, especially maternal folic acid ingestion and valproic acid exposure are also important. [Yerby: 2008]Prognosis
Infants with myelomeningocele typically undergo surgery to close the lesion soon after birth. Post repair, more than 75% of children born with myelomeningocele survive to early adulthood, although late complications are common. [Bowman: 2001] [Wong: 2001] Greater morbidity and mortality are associated with higher lesions, including the presence and difficulty of managing hydrocephalus and the presence of vesico-ureteral reflux and/or frequent urinary tract infections. [Wong: 2001]Prevalence
Neural tube defects occur in 1 per 1,365 births in Utah, with myelomeningocele comprising the vast majority (96% compared to only 4% for meningocele). The incidence is higher for families that already have one child with NTD (5%), two children with NTD (10%), or one parent with NTD (10%). Spina bifida occulta is very common in the general population, with some estimates as high as 40%, although most people with this form are unaware of it.Impact
Spina bifida is the second most common cause of chronic disability in young adults. [Nassau: 1997]Pearls And Alerts
On Treatment And Management Page
Helpful Articles
PubMed search for review articles on Neural Tube Defects in children for the last 3 years.
Frey L, Hauser WA.
Epidemiology of neural tube defects.
Epilepsia.
2003;44 Suppl 3:4-13.
PubMed abstract
Rossi A, Biancheri R, Cama A, Piatelli G, Ravegnani M, Tortori-Donati P.
Imaging in spine and spinal cord malformations.
Eur J Radiol.
2004;50(2):177-200.
PubMed abstract
Neural Tube Defects Module Authors
| Authors: | Paula Peterson APRN, PNP, 11/2008 Lynne M Kerr MD, PhD, 11/2008 |
| Reviewing Author: | Sarah Winter M.D., 7/2008 |
| Content Last Updated: | 2/2009 |
The authors listed above are responsible for the overall Neural Tube Defects Module. Authors contributing to individual pages in the module are listed on those pages.
Page Bibliography
Bowman RM, McLone DG, Grant JA, Tomita T, Ito JA.
Spina bifida outcome: a 25-year prospective.
Pediatr Neurosurg.
2001;34(3):114-20.
PubMed abstract
Brand MC.
Part 3: examination of the newborn with closed spinal dysraphism.
Adv Neonatal Care.
2007;7(1):30-40; quiz 41-2.
PubMed abstract
An excellent discussion of the types of and significance of cutaneous markers for closed neural tube defects in babies.
Deak KL, Siegel DG, George TM, Gregory S, Ashley-Koch A, Speer MC.
Further evidence for a maternal genetic effect and a sex-influenced effect contributing to risk for human neural tube defects.
Birth Defects Res A Clin Mol Teratol.
2008;82(10):662-9.
PubMed abstract
Finnell RH, Gould A, Spiegelstein O.
Pathobiology and genetics of neural tube defects.
Epilepsia.
2003;44 Suppl 3:14-23.
PubMed abstract
This is an interesting article about the embryology of NTD and the genetic and environmental contributions to NTD.
Kaufman BA.
Neural tube defects.
Pediatr Clin North Am.
2004;51(2):389-419.
PubMed abstract
Interesting article regarding the embryology of NTD. This article also points out that NTDs are not progressive and any deterioration
should prompt evaluation and treatment.
Nassau JH, Drotar D.
Social competence among children with central nervous system-related chronic health conditions: a review.
J Pediatr Psychol.
1997;22(6):771-93.
PubMed abstract
Wong LY, Paulozzi LJ.
Survival of infants with spina bifida: a population study, 1979-94.
Paediatr Perinat Epidemiol.
2001;15(4):374-8.
PubMed abstract
Yerby MS.
Teratogenicity and antiepileptic drugs: potential mechanisms.
Int Rev Neurobiol.
2008;83:181-204.
PubMed abstract