Introduction:

Neural tube defects (NTDs) are among the most prevalent congenital anomalies resulting from improper neural tube closure along with the overlying mesoderm and ectoderm. These anomalies occur at an estimated rate of 1.5 per 1,000 live births, with a recurrence risk of 5 per 100 births in a second sibling. In North India, the incidence is reported to be as high as 3.9–9 per 1,000 live births1.

Etiology and Classification

NTDs primarily follow a multifactorial inheritance pattern. The lumbosacral region is the most frequently affected site; however, defects can involve any part of the spine, with variations in length and severity2.

Classification of Neural Tube Defects (NTDs): The spectrum of NTDs includes:

1. Spina Bifida

• Spina Bifida Occulta – A mild form where the spinal cord and meninges remain intact, often without symptoms.

• Meningocele – A sac-like protrusion of the meninges through a vertebral defect.

• Meningomyelocele – The most severe form, where both meninges and spinal cord herniate, causing neurological deficits.

2. Anencephaly

• Characterized by partial or complete absence of the brain and calvaria.

• A leading cause of fetal and neonatal mortality, often resulting in stillbirth or early neonatal death.

3. Encephalocele

• Herniation of brain tissue and meninges through a skull defect.

• Commonly associated with neurological deficits and developmental delays.

4. Craniorachischisis

• A severe form combining anencephaly and a continuous spinal defect, leaving neural tissue exposed.

5. Iniencephaly

• A rare condition characterized by occipital dysraphism with severe neck and spinal retroflexion.

Associated Complications and Long-Term Impact

NTDs often coexist with other congenital anomalies and systemic dysfunctions, including:
✅ Lower limb paralysis
✅ Bladder and bowel dysfunction
✅ Learning disabilities
✅ Hydrocephalus (due to Arnold-Chiari Type II malformation3)

In severe cases, individuals may experience neurological deficits, motor and physical disabilities, psychosocial challenges, and financial burdens due to lifelong medical care and rehabilitation needs1,4.

Clinical Presentation:

Spina bifida occulta accounts for approximately 5% of cases and is often asymptomatic. Meningocele and meningomyelocele are raw, red, fleshy plaques consisting of meninges, cerebrospinal fluid (CSF), nerve roots, and dysplastic spinal cord2.

• Meningocele: The sac is covered by skin and typically lacks neurological deficits.

• Meningomyelocele: Characterized by flaccid paraparesis, sensory deficits, fecal and urinary incontinence, and hydrocephalus4.

• Arnold-Chiari malformation may lead to facial weakness, swallowing difficulties, tongue movement impairment, and laryngeal stridor5.

Diagnosis of neural tube defects:

Management of NTDs:

A multidisciplinary team approach involving a pediatrician, neurologist, neurosurgeon, urologist, orthopedic surgeon, physiotherapist, social worker, and psychiatrist is essential. The severity of paralysis, presence of hydrocephalus, kyphosis, associated congenital anomalies, and infections influence treatment decisions7.

Surgical interventions include early closure of defects and ventriculoperitoneal (VP) shunting for hydrocephalus. Open lesions with CSF drainage should be surgically closed within 24 hours, while closed lesions require intervention within 48 hours8.

Lorber’s Criteria for Selective Surgery

Surgical intervention is not recommended in cases of:
🚫 Severe paraplegia below the L3 level
🚫 Kyphosis or scoliosis
🚫 Gross hydrocephalus
🚫 Major congenital anomalies
🚫 Intracerebral birth injuries or neonatal ventriculitis9

Prognosis

Delayed intervention increases the risk of neurological deterioration, infections, and progressive hydrocephalus. Long-term complications include:
-Hydrocephalus (80–90%) due to Arnold-Chiari Type II malformation
-Urinary tract infections, incontinence, and constipation
-Intellectual deterioration and psychosocial challenges
-Epilepsy (10–30%)
-Visual impairments (30%)
-Shunt infections (25%)

Mortality rates are significant, with 2% of affected infants dying during initial hospitalization and 15% not surviving beyond 10 years10.

Prevention of NTDs:

Primary prevention includes periconceptional folic acid supplementation and food fortification. Counseling is vital for families with an affected child, as the recurrence risk is:
✅ 3.5% with one affected child
✅ 10% with two affected children
✅ 25% with three affected children6,11

Supplementation with 0.4 mg of folic acid daily is recommended for all women of reproductive age. However, women with a history of NTD-affected pregnancies should receive 4 mg per day, starting at least two months before conception and continuing through the first trimester12.

Other preventive strategies include:
✅ Screening for maternal MTHFR polymorphisms in recurrent NTD cases
✅ Supplementation with zinc and vitamin A
✅Avoiding teratogenic exposures (e.g., valproate, carbamazepine, alcohol, radiation, uncontrolled diabetes) 13.

References

1. Ghai OP, Paul VK, Bagga A. Essential Pediatrics. 10th ed. New Delhi: CBS Publishers; 2023. p. 398-402.

2. Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM. Nelson Textbook of Pediatrics. 21st ed. Philadelphia: Elsevier; 2020. p. 2051-2055.

3. Hockenberry MJ, Wilson D, Rodgers CC. Wong’s Essentials of Pediatric Nursing. 10th ed. St. Louis: Elsevier; 2017. p. 1121-1124.

4. Volpe JJ. Neurology of the Newborn. 6th ed. Philadelphia: Elsevier; 2018. p. 976-982.

5. Sadler TW. Langman’s Medical Embryology. 14th ed. Philadelphia: Wolters Kluwer; 2019. p. 216-220.

6. Botto LD, Moore CA, Khoury MJ, Erickson JD. Neural-tube defects. N Engl J Med. 1999;341(20):1509-19.

7. Greene ND, Copp AJ. Neural tube defects. Annu Rev Neurosci. 2014;37:221-42.

8. Stevenson RE, Hall JG. Human malformations and related anomalies. 3rd ed. Oxford: Oxford University Press; 2016. p. 648-660.

9. Mitchell LE, Adzick NS, Melchionne J, Pasquariello PS, Sutton LN, Whitehead AS. Spina bifida. Lancet. 2004;364(9448):1885-95.

10. Jentink J, Loane MA, Dolk H, Barisic I, Garne E, Wellesley D, et al. Valproic acid monotherapy in pregnancy and major congenital malformations. N Engl J Med. 2010;362(23):2185-93.

11. De-Regil LM, Peña-Rosas JP, Fernández-Gaxiola AC, Rayco-Solon P. Effects and safety of periconceptional folate supplementation. Cochrane Database Syst Rev. 2015;(12):CD007950.

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