What is Spina Bifida? Understanding Causes, Types, Symptoms, and Prevention

Spina bifida is a birth defect that occurs when the spine and spinal cord do not form properly. It falls under a group of conditions known as neural tube defects. During early pregnancy, the neural tube is the embryonic structure that develops into the baby’s brain, spinal cord, and the protective tissues around them.

Typically, the neural tube closes completely about 28 days after conception. However, in babies with spina bifida, a portion of this neural tube fails to close fully. This incomplete closure can affect the spinal cord and the bones of the spine, potentially leading to a range of disabilities.

The severity of spina bifida can vary widely, from mild forms with minimal symptoms to more severe types causing significant physical challenges. The symptoms experienced depend on the location and size of the opening in the spine, and whether the spinal cord and nerves are affected. While early surgical intervention is often necessary for certain types of spina bifida, it’s important to understand that surgery may not fully restore lost function.

Types of Spina Bifida: Occulta, Meningocele, and Myelomeningocele

Spina bifida is categorized into different types, each varying in severity and impact on the individual. The main types are spina bifida occulta, myelomeningocele, and meningocele.

Spina Bifida Occulta: The Hidden Form

Spina bifida occulta, meaning “hidden” spina bifida, is the mildest and most common form. It is characterized by a small gap or separation in one or more of the vertebrae, the bones of the spine. In spina bifida occulta, the spinal cord and nerves are usually not affected.

Often, individuals with spina bifida occulta are unaware they have the condition. It is frequently discovered incidentally during imaging tests, such as X-rays, performed for unrelated reasons. In many cases, spina bifida occulta causes no symptoms and requires no treatment.

Myelomeningocele: The Most Severe Type of Spina Bifida

Myelomeningocele, also known as open spina bifida, is the most severe type. In this condition, the spinal canal remains open along several vertebrae, typically in the lower or middle back. Critically, part of the spinal cord, along with its protective covering (meninges) and spinal nerves, protrudes through this opening at birth, forming a visible sac on the baby’s back.

The exposed tissues and nerves in myelomeningocele are vulnerable to infection, making prompt surgical intervention after birth essential. Myelomeningocele can lead to significant disabilities, including varying degrees of paralysis or weakness in the legs, and bowel and bladder dysfunction. Hydrocephalus, a buildup of fluid in the brain, is also commonly associated with myelomeningocele.

Meningocele: A Rare Form

Meningocele is a rare type of spina bifida. In meningocele, a sac containing spinal fluid protrudes through an opening in the spine, similar to myelomeningocele. However, the key difference is that in meningocele, the spinal cord itself is not within this sac and the spinal nerves are typically not affected.

While nerve damage is less common in meningocele compared to myelomeningocele, babies with meningocele may still experience some challenges with bodily functions, particularly bladder and bowel control. The long-term effects and required treatments vary depending on the specific case.

Spina Bifida Symptoms: Recognizing the Signs

The symptoms of spina bifida are diverse and depend heavily on the type of spina bifida and its severity, as well as individual variations.

Spina Bifida Occulta Symptoms: As mentioned, spina bifida occulta often presents with no noticeable symptoms. In some instances, there may be visible signs on the newborn’s skin overlying the small spinal gap. These skin indicators can include:
- A small tuft of hair.
- A minor dimple.
- A birthmark.
It’s important to note that while these skin markings are often benign, they can sometimes indicate an underlying spinal cord issue. In such cases, further investigations like MRI or spinal ultrasound in newborns may be recommended.
Meningocele Symptoms: Meningocele can sometimes affect bladder and bowel function, leading to difficulties with continence. The severity of these symptoms varies among individuals.
Myelomeningocele Symptoms: Myelomeningocele, being the most severe form, presents with the widest range of symptoms. Key symptoms include:
- Visible Sac: At birth, a sac is present on the baby’s back, typically in the lower or middle region, where the spinal canal is open. This sac contains membranes and part of the spinal cord or nerves.
- Neurological Issues: Babies with myelomeningocele often experience bladder and bowel dysfunction due to nerve involvement. Weakness or paralysis in the legs is also common, with the degree of impairment depending on the level of spinal involvement.
- Hydrocephalus: A significant number of babies with myelomeningocele develop hydrocephalus, an accumulation of fluid in the brain. This excess fluid can increase pressure within the skull and potentially damage brain tissue if not managed.

When to Seek Medical Advice for Spina Bifida

Myelomeningocele is usually diagnosed either before birth through prenatal screenings or immediately after birth due to its visible nature and severity. In these cases, medical care is readily initiated. Children diagnosed with myelomeningocele require lifelong specialized care from a multidisciplinary team of healthcare professionals. This team helps manage the various complications and ensures the child’s well-being throughout their life. Parents and families receive comprehensive education about potential complications and necessary monitoring.

Spina bifida occulta, on the other hand, often does not require immediate or specialized medical attention as it typically causes no symptoms or complications. Routine pediatric care is generally sufficient for children with spina bifida occulta.

If you have concerns about spina bifida, whether for yourself or a child, consulting with a healthcare professional is always recommended for accurate diagnosis and appropriate guidance.

Causes of Spina Bifida: Multifactorial Origins

The exact cause of spina bifida remains unknown. Medical research suggests that spina bifida likely arises from a complex interplay of genetic, nutritional, and environmental risk factors. This multifactorial etiology means that several elements can contribute to the development of spina bifida.

One significant factor identified is a family history of neural tube defects. Having a family member with spina bifida or other neural tube defects increases the likelihood of a child being born with spina bifida. Furthermore, inadequate intake of folate, also known as vitamin B-9, during pregnancy is strongly implicated as a risk factor.

Risk Factors for Spina Bifida: Identifying Potential Influences

While the precise cause is elusive, several risk factors have been identified that can increase the probability of spina bifida. These include:

Folate Deficiency: Insufficient folate levels in the pregnant person’s body are a major risk factor. Folate, the natural form of vitamin B-9, is crucial for healthy fetal development, particularly the neural tube. Folic acid, the synthetic form found in supplements and fortified foods, is also vital. Folate deficiency significantly elevates the risk of neural tube defects like spina bifida.
Family History: As mentioned, a family history of neural tube defects, including spina bifida, increases the risk. If a couple has had one child with a neural tube defect, the risk of recurrence in subsequent pregnancies is slightly higher. This risk escalates further if two previous children have been affected. Additionally, individuals born with a neural tube defect have a higher chance of having children with spina bifida. However, it’s important to note that most babies with spina bifida are born to parents with no known family history of the condition.
Certain Medications: The use of certain medications during pregnancy, particularly anti-seizure drugs like valproic acid, is associated with an increased risk of spina bifida. These medications can interfere with the body’s ability to utilize folate and folic acid effectively.
Pre-gestational Diabetes: Poorly controlled diabetes in the pregnant person before conception increases the risk of spina bifida. Managing diabetes effectively before pregnancy is crucial.
Obesity: Obesity at the time of pregnancy is also linked to a higher risk of spina bifida. Maintaining a healthy weight before and during pregnancy is advised.
Hyperthermia (Increased Body Temperature): Some research suggests that elevated body temperature in the early weeks of pregnancy may increase spina bifida risk. This hyperthermia can be caused by fever or exposure to high temperatures such as in saunas or hot tubs.

If you have any of these risk factors, especially if you are planning a pregnancy, it’s essential to discuss them with your healthcare provider. They may recommend higher doses of folic acid, even before conception, and review any medications you are taking to assess and mitigate potential risks.

Spina Bifida Complications: Understanding Potential Challenges

Spina bifida can lead to various complications, the nature and severity of which depend on factors like the size and location of the spinal opening, whether the affected area is covered by skin, and which spinal nerves are involved. It’s important to remember that not every child with spina bifida will experience all possible complications, and many complications are treatable.

Mobility Issues: Nerve damage below the affected spinal area can impair muscle control in the legs, leading to weakness or paralysis. The ability to walk varies greatly depending on the level and extent of the spinal defect and the care received.
Orthopedic Complications: Muscle weakness in myelomeningocele can cause orthopedic problems, including scoliosis (curved spine), clubfoot, hip dislocation, joint conditions, and muscle contractures (shortened, tight muscles).
Bowel and Bladder Dysfunction: Nerves controlling the bladder and bowel are often affected in myelomeningocele, leading to incontinence.
Hydrocephalus: Fluid buildup in the brain (hydrocephalus) is common in myelomeningocele. Shunts are often surgically placed to drain excess fluid.
Shunt Malfunction: Shunts can malfunction or become infected, requiring prompt medical attention. Warning signs include headaches, vomiting, sleepiness, irritability, shunt swelling, confusion, vision changes, feeding difficulties, and seizures.
Chiari Malformation Type 2: This condition, common in myelomeningocele, involves the brainstem extending into the spinal canal. It can cause breathing, swallowing, and arm weakness issues, sometimes requiring surgery.
Meningitis: Infection of brain tissues (meningitis) is a serious risk in myelomeningocele due to exposed tissues.
Tethered Spinal Cord: Scar tissue after surgery can tether the spinal cord, limiting its growth and potentially causing muscle, bowel, or bladder problems. Surgery can address this.
Sleep-Disordered Breathing: Sleep apnea and other sleep issues are more common in spina bifida, especially myelomeningocele, requiring evaluation and treatment.
Skin Problems: Reduced sensation can lead to skin wounds, blisters, and infections, particularly on feet, legs, and buttocks. Latex allergy is also more prevalent in spina bifida.
Other Complications: Urinary tract infections, gastrointestinal issues, learning disabilities (especially in myelomeningocele), and depression can occur as children with spina bifida age.

Spina Bifida Prevention: The Crucial Role of Folic Acid

You can significantly reduce the risk of having a baby with spina bifida and other neural tube defects by ensuring adequate folic acid intake. Starting folic acid supplementation at least one month before conception and continuing throughout the first trimester of pregnancy is highly recommended.

Prioritizing Folic Acid Intake

Sufficient folic acid in the body during the early weeks of pregnancy is critical for preventing spina bifida. Because many individuals may not realize they are pregnant in these early weeks, experts advise all people of childbearing age to take a daily supplement of 400 micrograms (mcg) of folic acid.

In addition to supplements, consuming foods naturally rich in folate or fortified with folic acid is beneficial. Fortified foods include enriched bread, pasta, rice, and certain breakfast cereals. Folate may be listed on food labels as the natural form of folic acid found in foods.

Planning for Pregnancy: Folic Acid Recommendations

Adults planning pregnancy or who could become pregnant should aim for 400 to 800 mcg of folic acid daily. Folic acid from supplements is more readily absorbed by the body compared to folate from food sources. Vitamin supplements containing folic acid are a key preventive measure against spina bifida and may also reduce the risk of other birth defects like cleft lip, cleft palate, and some heart conditions.

A healthy diet rich in folate-containing foods is also encouraged. Natural sources of folate include beans, peas, citrus fruits and juices, egg yolks, cow’s milk, avocados, and dark green vegetables like broccoli and spinach.

When Higher Folic Acid Doses are Necessary

In certain situations, higher doses of folic acid are recommended. If you have spina bifida yourself or have previously had a child with spina bifida, increased folic acid intake is crucial before subsequent pregnancies. Similarly, individuals taking anti-seizure medications or those with diabetes may also benefit from higher folic acid doses. Always consult your healthcare provider to determine the appropriate folic acid dosage for your specific needs before taking additional supplements.

By Mayo Clinic Staff

Related Information

References

What Is Spina Bifida? Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/spinabifida/facts.html. Accessed Oct. 4, 2023.
Spina bifida. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/spina-bifida#. Accessed Oct. 4, 2023.
Spina bifida. Merck Manual Professional Version. https://www.merckmanuals.com/professional/pediatrics/congenital-neurologic-anomalies/spina-bifida?query=spina%20bifida#. Accessed Oct. 4, 2023.
Ferri FF. Spina bifida. In: Ferri’s Clinical Advisor 2024. Elsevier; 2024. https://www.clinicalkey.com. Accessed Oct. 4, 2023.
Bowman RM. Myelomeningocele (spina bifida): Anatomy, clinical manifestations and complications. https://www.uptodate.com/contents/search. Accessed Oct. 4, 2023.
MAFP1 alpha-fetoprotein (AFP), single marker screen, maternal, serum. Mayo Medical Laboratories. https://www.mayocliniclabs.com/test-catalog/Overview/113382#Clinical-and-Interpretive. Accessed Oct. 4, 2023.
Holcomb GW III, et al., eds. Neurosurgical conditions. In: Holcomb and Ashcraft’s Pediatric Surgery. 7th ed. Elsevier; 2020. https://www.clinicalkey.com. Accessed Oct. 4, 2023.
Gleason CA, et al., eds. Congenital malformations of the central nervous system. In: Avery’s Diseases of the Newborn. 11th ed. Elsevier; 2024. https://www.clinicalkey.com. Accessed Oct. 4, 2023.
Bowman RM. Myelomeningocele (spina bifida): Management and outcome. https://www.uptodate.com/contents/search. Accessed Oct. 4, 2023.
Dietary supplement fact sheet: Folate. Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/folate-HealthProfessional/. Accessed Oct. 4, 2023.
Paslaru FG, et al. Myelomeningocele surgery over the 10 years following the MOMS trial: A systematic review of outcomes in prenatal versus postnatal surgical repair. Medicina. 2021; doi:10.3390/medicina57070707.
Rocque BG, et al. Caring for the child with spina bifida. Pediatric Clinics of North America. 2021; doi:10.1016/j.pcl.2021.04.013.
Schindelmann KH, et al. Systematic classification of spina bifida. Journal of Neuropathology and Experimental Neurology. 2021; doi:10.1093/jnen/nlab007.
Ami TR. Allscripts EPSi. Mayo Clinic. Sept. 4, 2023.
Wilson PE, et al. Mobility guidelines for the care of people with spina bifida. Journal of Pediatric Rehabilitation Medicine. 2020; doi:10.3233/PRM-200744.
Viswanathan M, et al. Folic acid supplementation to prevent neural tube defects: Updated evidence report and systematic review for the U.S. Preventive Services Task Force. JAMA. 2023; doi:10.1001/jama.2023.9864.
Data and statistics on spina bifida. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/spinabifida/data.html. Accessed Oct. 13, 2023.
Kancherla V. Neural tube defects: A review of global prevalence, causes and primary prevention. Child’s Nervous System. 2023; doi:10.1007/s00381-023-05910-7.
Koch VH, et al. Multidisciplinary management of people with spina bifida across the lifespan. Pediatric Nephrology. 2023; doi:10.1007/s00467-023-06067-w.
Dukhovny S, et al. Neural tube defects: Overview of prenatal screening, evaluation and pregnancy management. https://www.uptodate.com/contents/search. Accessed Oct. 4, 2023.
Lee SY, et al. Fetal repair of neural tube defects. Clinics in Perinatology. 2022; doi:10.1016/j.clp.2022.06.004.
Hydrocephalus and shunts. Spina Bifida Association. https://www.spinabifidaassociation.org/resource/hydrocephalus-and-shunts/. Accessed Oct. 10, 2023.
Health issues and treatments for spina bifida. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/spinabifida/treatment.html. Accessed Oct. 10, 2023.
Natural rubber latex allergy. Spina Bifida Association. https://www.spinabifidaassociation.org/resource/latex-2/. Accessed Oct. 10, 2023.
Barry MJ, et al. Folic acid supplementation to prevent neural tube defects: U.S. Preventative Services Task Force reaffirmation recommendation statement. JAMA. 2023; doi:10.1001/jama.2023.12876.
Infants and children. Spina Bifida Association. https://www.spinabifidaassociation.org/infants-children/. Accessed Oct. 12, 2023.
Kritikos TK, et al. Mental health guidelines for the care of people with spina bifida. Journal of Pediatric Medicine. 202; doi:10.3233/PRM-200719.
Palomaki GE, et al. Laboratory screening and diagnosis of open neural tube defects, 2019 revision: A technical standard of the American College of Medical Genetics and Genomics (ACMG). Genetics in Medicine. 2020: doi:10.1038/s41436-019-0681-0.
Narang K, et al. Obstetric outcomes after fetal intervention — A single-center descriptive review. Journal of Maternal-Fetal and Neonatal Medicine. 2022; doi:10.1080/14767058.2021.1943658.