Spina Bifida Occulta

Spina bifida occulta is the mildest and most common form of spina bifida, a birth defect where there is a small gap in the bones of the spine. The term "occulta" means hidden, as it often causes no symptoms and the spinal cord usually remains unaffected. Many people have this condition without ever knowing, and it rarely requires medical treatment.

What is Spina Bifida Occulta?

Spina bifida occulta is the mildest type of spina bifida, a condition where one or more bones in the spine (vertebrae) do not fully close, leaving a small gap. Unlike other forms, the spinal cord and nerves usually remain inside the spinal canal and are not damaged. It is often called "hidden" spina bifida because most people have no symptoms and are unaware they have it.

The spine is made up of many small bones called vertebrae. These bones protect the spinal cord, which carries messages between your brain and body. In spina bifida occulta, there is a small opening or gap in one or more of these vertebrae, typically in the lower back. However, the spinal cord itself usually remains protected within the spinal canal. This condition is very common. About 1 in 10 to 1 in 5 people (10% to 20%) have spina bifida occulta, according to Mayo Clinic and MedlinePlus. Most people never experience any problems or even know they have it. Think of it like a small, harmless crack in a wall that doesn't affect the building's overall structure or function. Because the spinal cord is usually unaffected, spina bifida occulta often does not cause any health issues. It is different from more severe forms of spina bifida, where the spinal cord or its coverings protrude through the opening in the spine, leading to more significant health challenges.

Symptoms

Most people with spina bifida occulta have no symptoms and never know they have the condition. Sometimes, a visible sign on the skin over the lower back may be present, such as a dimple, a patch of hair, a dark spot, or a small fatty lump. Rarely, nerve problems can develop if the spinal cord becomes stretched or stuck.

For the vast majority of individuals, spina bifida occulta is asymptomatic, meaning it causes no noticeable signs or symptoms. It is often discovered by chance during imaging tests performed for other reasons. When symptoms do occur, they are usually subtle and localized to the skin above the spinal defect. These skin signs can include a small, deep dimple, an unusual tuft of hair, a discolored patch of skin (like a birthmark), or a small fatty lump (lipoma). These marks are typically located on the lower back, directly over the area where the vertebral bones did not fully close. While these signs are often harmless, they can sometimes indicate an underlying spinal issue. In rare cases, spina bifida occulta can lead to symptoms if the spinal cord becomes "tethered." This means the spinal cord gets stretched or stuck to the surrounding tissues as a child grows. Symptoms of a tethered cord can include progressive weakness or numbness in the legs, changes in bladder or bowel control, or foot deformities. These nerve-related symptoms usually develop later in childhood or adulthood and require medical evaluation.

Causes & risk factors

The exact cause of spina bifida occulta is unknown, but it develops very early during pregnancy when the baby's spine is forming. It is thought to result from a combination of genetic and environmental factors. Folic acid deficiency is a known risk factor for all types of spina bifida.

Spina bifida occulta occurs during the first month of pregnancy, often before a person even knows they are pregnant. At this stage, a structure called the neural tube forms, which eventually develops into the baby's brain and spinal cord. In spina bifida, the neural tube does not close completely. While the precise reason for this incomplete closure in spina bifida occulta is not fully understood, researchers believe it involves a complex interplay of genetic predispositions and environmental influences. This means that both inherited traits and factors in the mother's environment during early pregnancy may contribute to its development. One significant risk factor for all forms of spina bifida, including occulta, is a deficiency of folic acid. Folic acid is a B vitamin crucial for the healthy development of the neural tube. Taking folic acid supplements before and during early pregnancy can significantly reduce the risk of neural tube defects. However, even with adequate folic acid, spina bifida occulta can still occur, as it is not the sole cause.

How it's diagnosed

Spina bifida occulta is most often discovered by chance when imaging tests, such as an X-ray, MRI, or CT scan, are performed for other medical reasons. If a baby has certain skin signs on their lower back, a doctor might order these imaging tests specifically to check for the condition.

Because spina bifida occulta usually causes no symptoms, it is frequently an incidental finding. This means it is found unexpectedly when a person undergoes an imaging test for an unrelated issue, such as a back injury or a kidney problem. An X-ray of the spine can show the small gap in the vertebrae. If a newborn or infant has a suspicious skin mark on their lower back—like a deep dimple, a patch of hair, or a fatty lump—a doctor may recommend further investigation. Magnetic resonance imaging (MRI) or computed tomography (CT) scans are often used in these cases. An MRI provides detailed images of soft tissues, including the spinal cord and nerves, which can help determine if there is a tethered cord or other related issues. These imaging tests allow doctors to visualize the bones of the spine and the spinal cord itself. They can confirm the presence of the vertebral defect and assess whether the spinal cord is affected. Early diagnosis, especially when skin signs are present, can help monitor for potential complications, though most cases remain benign.

Treatment options

Most people with spina bifida occulta do not need any treatment because the condition typically causes no symptoms or problems. If symptoms develop due to a tethered spinal cord, surgery may be recommended to release the cord and prevent further nerve damage or alleviate existing symptoms.

For the vast majority of individuals with spina bifida occulta, no specific treatment is necessary. Since the spinal cord is usually unaffected and there are no symptoms, the condition does not impact daily life or require medical intervention. Regular check-ups with a doctor are usually sufficient to monitor for any changes. However, in the rare instances where a tethered spinal cord causes symptoms, treatment becomes necessary. A tethered cord occurs when the spinal cord becomes abnormally attached to the surrounding tissues, causing it to stretch as the child grows. This stretching can lead to nerve damage and symptoms like leg weakness, numbness, or bladder/bowel problems. If a tethered cord is diagnosed and is causing symptoms, surgery is the primary treatment option. The goal of this surgery is to release the spinal cord from the surrounding tissue, allowing it to move freely within the spinal canal. This procedure aims to relieve pressure on the nerves, prevent further damage, and potentially improve or stabilize existing symptoms. The decision for surgery is carefully considered based on the severity and progression of symptoms, as noted by the Cochrane Library.

Recovery & outlook

The outlook for most people with spina bifida occulta is excellent; they typically live full, healthy lives without any issues or limitations. If surgery is needed for a tethered cord, recovery varies, but many see improvement or stabilization of symptoms, allowing them to maintain a good quality of life.

For the overwhelming majority of people, spina bifida occulta is a benign condition that does not affect their health, development, or lifespan. Many individuals go through their entire lives unaware they have it. They can participate in all normal activities, including sports, and do not face any specific restrictions due to the condition. Even when skin signs are present, if there are no underlying neurological issues, the outlook remains excellent. Regular monitoring by a healthcare provider can ensure that any rare complications, such as a tethered cord, are identified early. If surgery for a tethered cord is performed, the recovery period will vary depending on the individual's age, overall health, and the extent of the surgery. While surgery can often prevent symptoms from worsening and may improve some existing issues, it does not reverse any nerve damage that has already occurred. However, with appropriate medical care and rehabilitation, individuals who undergo surgery can often manage their symptoms effectively and maintain a good quality of life.

When to see a doctor

You should see a doctor if your baby has any suspicious skin signs on their lower back, such as a deep dimple, a tuft of hair, or a discolored patch. Adults or children should also see a doctor if they develop new or worsening leg weakness, numbness, changes in bladder or bowel control, or foot problems.

It is important to have a doctor evaluate any unusual skin markings on a baby's lower back, especially if they are deep, have hair growing from them, or are discolored. While many such marks are harmless, they can sometimes be the only visible sign of spina bifida occulta or a more complex underlying spinal condition that might require monitoring. For older children and adults, the development of new neurological symptoms warrants a medical visit. These symptoms could indicate a tethered spinal cord, which is a rare but treatable complication of spina bifida occulta. Watch for signs such as increasing weakness or numbness in one or both legs, difficulty walking, changes in the shape or function of the feet, or new problems with bladder or bowel control. Early detection and evaluation of these symptoms are crucial. A doctor can perform a thorough examination and order appropriate imaging tests to determine the cause of the symptoms and recommend the best course of action. Prompt medical attention can help prevent further nerve damage and improve outcomes.

Frequently asked questions

Is spina bifida occulta a serious condition?

No, for most people, spina bifida occulta is not a serious condition. It rarely causes symptoms or health problems and often goes undiagnosed throughout a person's life. It is the mildest form of spina bifida.

Can spina bifida occulta cause back pain?

Spina bifida occulta itself usually does not cause back pain. However, in rare cases where a tethered spinal cord develops, it can lead to back pain, along with leg weakness or numbness. If you experience new back pain with these symptoms, see a doctor.

Can spina bifida occulta be prevented?

While the exact cause is unknown, taking folic acid supplements before and during early pregnancy significantly reduces the risk of all neural tube defects, including spina bifida. However, it does not guarantee prevention, as other factors are involved.

Will spina bifida occulta affect my child's development?

In the vast majority of cases, spina bifida occulta does not affect a child's physical or cognitive development. Children with this condition typically grow and develop normally, without any limitations or special needs related to it.

Can I exercise or play sports if I have spina bifida occulta?

Yes, most people with spina bifida occulta can exercise and play sports without any restrictions. Since the condition usually causes no symptoms and the spinal cord is unaffected, it does not typically limit physical activity. Consult your doctor if you have concerns.

Is spina bifida occulta hereditary or genetic?

Spina bifida occulta is thought to involve a combination of genetic and environmental factors. While it can run in families, it is not strictly hereditary in a simple way. Having a family history may slightly increase risk, but many cases occur without any known family history.

Sources

• MedlinePlus — Spina Bifida Occulta
• Mayo Clinic — Spina Bifida Occulta
• Cochrane Library — Spina Bifida Occulta