Basics of Spina Bifida

What is spina bifida?

Spina bifida, is a neural tube birth defect in which there is abnormal development of the back bones, spinal cord, surrounding nerves and the fluid-filled sac that surrounds the spinal cord. This neurological condition can cause a portion of the spinal cord and the surrounding structures to develop outside, instead of inside, the body. The defect can occur anywhere along the spine, with 85 percent of the defects occurring in the lower back and the remainder in the upper back and neck. Although the original defect can be repaired by a CHOC neurosurgeon, the nerve damage that is caused by the defect will remain. Generally, the higher up towards the child’s head the original defect occurs, the more severe the effects.

Spina bifida is an incurable, condition that affects the neuromuscular and neuroskeletal systems of the body. Children with spina bifida often require lifelong medical care as the condition’s effects can change throughout their lifetime.

At CHOC, our treatment focuses on preventing and minimizing complications and conditions common with a diagnosis of spina bifida and helping children live as normal of a life as possible.

What are the types of spina bifida?

The types of spina bifida include the following:

• Spina bifida occulta is a mild form of spina bifida in which the spinal cord and the surrounding structures remain inside the baby, but the back bones in the lower back area fail to form normally. There may be a hairy patch, dimple, or birthmark over the area of the defect. Other times, there may be no abnormalities in the area.
• In spina bifida occulta (as well as in other forms), there may be an associated tethering of the spinal cord, called tethered cord. In a tethered cord the lower end of the spinal cord stays attached to the base of the spine, rather than riding freely within the spinal canal.
• The tethered cord may not be diagnosed at birth and frequently causes no symptoms, although symptoms can develop later on in life. If may be required to release the tethered spinal cord or to repair orthopedic defects.
• Meningocele is a moderate form of spina bifida in which a fluid-filled sac is visible outside of the back area. The sac does not contain the spinal cord or nerves. Most children with meningocele have normal function in their legs, although some will have partial paralysis as well as urinary and/or bowel dysfunction. In meningocele, the spinal cord is frequently tethered. Almost all children with meningocele will require surgery to repair the sac and release the tethering.
• Lipomeningocele is a variation of meningocele spina bifida in which a fatty mass (lipoma) is attached (tethered) to the spine and pulls on it. The tethering can be fixed with surgery. Children with lipomeningocele may experience nerve damage. They may also have urinary and bowel problems.
• Myelomeningocele is a severe form of spina bifida in which the spinal cord and nerves develop outside of the body and are contained in a fluid-filled sac that is visible outside of the back area. These babies typically have weakness and loss of sensation below the defect. Problems with bowel and bladder function are also common. A majority of babies with myelomeningocele will also have hydrocephalus, a condition that causes the fluid inside the head to build up, causing pressure inside of the head to increase and the skull bones to expand to a larger than normal size.

What causes spina bifida?

Spina bifida is a type of neural tube defect. Neural tube defects, including spina bifida (open spine) and anencephaly (open skull), are seen in seven out of 10,000 live births in the United States.

During pregnancy, the human brain and spine begin as a flat plate of cells, which rolls into a tube, called the neural tube. If all or part of the neural tube fails to close, leaving an opening, this is known as an open neural tube defect (or ONTD). This opening may be left exposed (80 percent of the time), or covered with bone or skin (20 percent of the time).

Anencephaly and spina bifida are the most common types of ONTD. Spina bifida occurs when the neural tube fails to close somewhere along the spine.

In over 95 percent of cases, an ONTD occurs without a prior family history of these defects. ONTDs result from a combination of genes inherited from both parents, coupled with environmental factors. For this reason, ONTDs are considered multifactorial traits, meaning “many factors,” both genetic and environmental, contribute to their occurrence.

Some of the environmental factors that may contribute to ONTDs include obesity, uncontrolled diabetes in the mother, lack of folic acid in mother’s diet during pregnancy and certain prescription medications. According to the Centers for Disease Control and Prevention (CDC), the occurrence rate of ONTDs can vary from state to state and from country to country.

ONTDs are seen five times more often in females than males. Once a child with an ONTD has been born in the family, the chance for an ONTD to occur again is increased to 4 percent. It is important to understand that the type of neural tube defect can differ the second time. For example, one baby could be born with anencephaly, while a second baby could have spina bifida (not anencephaly).

What are the symptoms of spina bifida?

The following are the most common symptoms of spina bifida. However, each baby may experience symptoms differently. Symptoms may include:

• Abnormal appearance of the baby’s back, varying from a small, hairy patch or a dimple or birthmark, to a sac-like protrusion that is found along the back bone area.
• Bowel and bladder problems, including urinary retention, constipation and incontinence.
• Loss of feeling below the area of the lesion, especially in babies born with a meningocele or myelomeningocele.
• Inability to move the lower legs (paralysis).

The children may also have other problems related to spina bifida that include the following:

• Hydrocephalus (increased fluid and pressure in the head area that occurs in about 80 to 90 percent of cases).
• Heart problems.
• Orthopedic (bone) problems.
• Lower than normal intelligence level (although 80 percent of children have normal intelligence).

The symptoms of spina bifida may resemble other conditions or medical problems. Always consult your baby’s physician for a diagnosis.