Neural tube defect

Neural tube defects (NTDs) are a group of congenital malformations that occur when the neural tube — the embryonic structure that develops into the brain and spinal cord — fails to close completely during the first few weeks of pregnancy (typically between days 21 and 28 after conception). This group of conditions includes several well-known subtypes: anencephaly (absence of a major portion of the brain and skull), spina bifida (incomplete closure of the spinal column), and encephalocele (protrusion of brain tissue through an opening in the skull). The severity of NTDs ranges widely, from conditions incompatible with life (such as anencephaly) to milder forms like spina bifida occulta, which may be asymptomatic. The clinical features depend on the type and location of the defect. Spina bifida, the most common survivable form, can cause varying degrees of paralysis of the lower limbs, bladder and bowel dysfunction, hydrocephalus (accumulation of cerebrospinal fluid in the brain), orthopedic abnormalities, and learning difficulties. Anencephaly is uniformly fatal, with most affected infants being stillborn or dying shortly after birth. Encephalocele can cause intellectual disability, vision problems, and motor deficits depending on the amount of brain tissue involved. Neural tube defects have a multifactorial etiology involving both genetic susceptibility and environmental factors. Maternal folate (folic acid) deficiency is the best-established modifiable risk factor, and periconceptional folic acid supplementation has been shown to reduce the risk of NTDs by up to 70%. Other risk factors include maternal diabetes, obesity, certain anticonvulsant medications (particularly valproic acid), and genetic variants in folate metabolism pathways (such as MTHFR). Treatment depends on the specific defect: spina bifida may be treated with surgical closure of the defect either prenatally (fetal surgery) or shortly after birth, along with management of hydrocephalus through ventriculoperitoneal shunting. Lifelong multidisciplinary care involving neurosurgery, urology, orthopedics, and rehabilitation is often required for individuals with spina bifida. Prevention through folic acid fortification of food and supplementation remains the cornerstone of public health strategy.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Neural tube defect