Epidemiology of Spina Bifida Occulta and Tethered Cord Syndrome in Children

Incidence and Prevalence

• Neural tube defects: Neural tube defects are present in 1/1000 live births (1).
• Spina bifida aperta: Present in 5-6/100,000 live births (1).
• Spina bifida occulta: Occurs in 12% of the general population (8).
• Occult tethered cord: The true prevalence is difficult to assess because many patients are asymptomatic. Increasing incidence is probably an incidental finding associated with the widespread use of radiographic imaging (e.g., CT, MRI).

Age Distribution

• All ages: Spina bifida occulta may present at any age.

Sex Predilection

• Female:male ratio is 2:1 (1).

Geographic Distribution

• Regional differences: Rates of occurrence are higher in Ireland and Britain than in continental Europe. In the United States, the rate of occurrence is higher in Hispanics than in other ethnic groups. (1).

Risk Factors

• Familial: The biggest risk factor is a history of neural tube defect in a previous pregnancy.  The risk of developing a neural tube defect in a sibling is 3–8%. The risk is elevated in second- and third-degree relatives (1).
• Medical: The risk is increased up to 10-fold with maternal diabetes. Folic acid deficiency is also a risk. The incidence and prevalence of neural tube defects have declined since maternal supplementation with folic acid. Anti-epileptic agents (e.g., valproic acid and carbamazepine), which inhibit folate metabolism, increase relative risk (1).