What is spina bifida?

Spina bifida is a birth defect involving the spine, spinal cord and the protective covering of the spinal cord called the meninges. It is part of a group of disorders, called neural tube defects, that can occur during pregnancy. 

Causes

Spina bifida is caused by abnormal folding of cells during the early stages of an embryo's development (embryogenesis). The exact reason why this occurs is unknown, but genetic and nutritional factors, particularly a lack of folate (folic acid) during early pregnancy, appear to be involved. The abnormal folding of cells occurs specifically at the back of the embryo, on a specialised plate of cells called the neural plate.

During early development, the cells on the edge of the neural plate curl up at the edges and 'zip' together to form the neural tube. The neural tube later becomes the brain and spinal cord. Spina bifida occurs when the 'zip' does not close properly and part of the spinal cord is formed outside the tube. This can damage of the exposed spinal cord, which can affect various bodily functions.

Baby with spina bifida.Spina bifida may result in spinal cord exposure. 

Folate

A type of vitamin B involved in the creation of DNA and RNA. It plays a key role in cell growth and reproduction.

Risk factors

Risk factors associated with spina bifida include:

  • Family history of spina bifida;
  • Having a previous child with spina bifida, and;
  • Lack of folate during pregnancy.

Folate

A type of vitamin B involved in the creation of DNA and RNA. It plays a key role in cell growth and reproduction.

Types

There are three forms of spina bifida that vary in severity. These include:

Occulta

The mildest form of spina bifida is known as occulta. In occulta, the spinal column is not completely closed at the back, but there is normally no nerve damage and the meninges (the protective coverings of the spinal cord) are also undamaged. A tuft of hair or dimple usually marks the site and most people with this condition do not experience any symptoms. In some cases, people can experience incontinence, backaches and leg muscle changes.

Meningocele

The moderate form of spina bifida is known as meningocele. This occurs when the meninges are pushed through the opening of the vertebrae to form a sac filled with cerebrospinal fluid. This generally does not affect the spinal cord and therefore symptoms may not be present. In some cases, there can be paralysis and incontinence problems.

Myelomeningocele

The severe form of spina bifida is known as myelomeningocele. This condition occurs when both the meninges and the spinal cord protrude out of the vertebrae. This can cause the spinal cord to develop incorrectly, leading to spinal nerve damage. The severity of the condition depends on the location along the spine and the amount of spinal cord that is protruding. The condition tends to be worse when the opening is located higher on the back. This condition can lead to paralysis, incontinence problems and orthopaedic problems including scoliosis. In some cases, tissues and nerves are exposed, which can lead to infections that may be life-threatening.

Forms of spina bifida showing normal spine, spina bifida occulta, meningocele, and myelomeningocele.Different types of spina bifida. 

Paralysis

An inability to move or feel; a loss of muscle function or sensation.

Cerebrospinal fluid

The clear fluid that surrounds and protects the brain and the spinal cord.

Signs and symptoms

Depending on the spinal location, type and severity of spina bifida, various signs and symptoms may be present. These may include:

Paralysis

An inability to move or feel; a loss of muscle function or sensation.

Methods for diagnosis

If you are pregnant, there are prenatal tests that can be performed to identify any birth defects. They are generally accurate, but sometimes a prenatal test can wrongly indicate a defect or miss identifying the presence of defect. Some prenatal tests include:

Maternal serum alpha-fetoprotein test

This is a screening test that measures the level of alpha-fetoprotein (AFP) in a pregnant woman in the second trimester. This protein is naturally made by the fetus and the placenta, some of which crosses into the mother's bloodstream. If the level of alpha-fetoprotein is abnormally high, it can indicate that the fetus has an open neural tube defect.

Amniocentesis

An amniocentesis involves taking a sample of fluid from the sac that surrounds the growing fetus to identify the level of alpha-fetoprotein. This is a more accurate test to identify if spina bifida is present, but it cannot determine the severity of the condition. There also is a small risk of complications with this procedure, including damage to the growing fetus or miscarriage.

Ultrasound

If blood tests indicate high levels of alpha-fetoprotein, your doctor may recommend an ultrasound to confirm the presence of spina bifida. This test can create an accurate image of the baby growing inside you and can identify signs of spina bifida.

Prenatal

Before the birth of a baby.

Miscarriage

The loss of a pregnancy before 20 weeks.

Placenta

The organ that forms within the uterus of a pregnant woman to provide the fetus with nourishment from the blood supply of the mother.

Types of treatment

While there is no specific cure for spina bifida, there are some options available to treat and manage the condition. Generally the mildest form of spina bifida doesn't require any treatment. Some treatment options for moderate and severe conditions include:

Surgery

Surgery can be performed on individuals with meningocele, the moderate form of spina bifida, to insert the meninges back inside the vertebrae. Individuals with myelomeningocele, the severe form of spina bifida, generally will require surgery at birth to cover the exposed spinal cord and meninges with the newborn's muscle or skin. This operation can help prevent life-threatening infections. Surgery of a baby's spinal cord can also be performed before the baby is born. However, this procedure can be dangerous to the mother and increases the risk of premature birth.

Shunt insertion

A complication called hydrocephalus, which causes an accumulation of excess cerebrospinal fluid in the brain, can be treated with a shunt. This involves the insertion of a hollow tube into the ventricles of the brain to drain the excess fluid.

Ongoing care after birth

As a person with spina bifida grows and develops, surgical procedures may be required on legs and feet to help increase mobility. Wheelchairs, walking aids and braces can also help with mobility. Bladder surgery, the use of incontinence pads or a catheter may be required to manage urinary incontinence.

Catheter

A thin, flexible tube inserted through a narrow opening into a body cavity for removing fluid.

Cerebrospinal fluid

The clear fluid that surrounds and protects the brain and the spinal cord.

Ventricles

1. The two main heart chambers that eject blood back out of the heart. 2. A series of connecting cavities in the brain that contain the cerebrospinal fluid, which supports and protects the brain.

Potential complications

Some complications associated with spina bifida include:

Paralysis

An inability to move or feel; a loss of muscle function or sensation.

Cerebrospinal fluid

The clear fluid that surrounds and protects the brain and the spinal cord.

Arnold-Chiari malformation

A birth disorder in which the lower brainstem and parts of the brain protrude through the opening of the spinal cord at the base of the skull. It leads to problems with balance and coordination. It is unclear what causes it, but exposure to hazardous substances, poor nutrition or infection during pregnancy are some suggested causes.

Prognosis

Depending on the severity of spina bifida, the prognosis can vary. In most cases of mild spina bifida, there are no symptoms and an individual can live a normal life. In more moderate cases, surgery can be performed soon after birth to limit the effects of spina bifida. In some severe cases of spina bifida, debilitating complications, including paralysis, can occur.

Paralysis

An inability to move or feel; a loss of muscle function or sensation.

Prevention

To help prevent spina bifida, adequate amounts of folate can be taken during pregnancy. Folate is a B-group vitamin that has been proven to reduce the instances of spina bifida. Foods that are high in folate include bananas, oranges, spinach, asparagus and legumes. A tablet form of folate is available and is usually recommended in addition to the dietary intake. Taking 0.5 mg of folic acid daily for a month before and three months after conception can reduce the risk of spina bifida.

If there is a family history of cleft lip, spinal problems or if you are taking epilepsy medication your doctor will most likely prescribe a higher dose of folate to lower your risk. 

Folate

A type of vitamin B involved in the creation of DNA and RNA. It plays a key role in cell growth and reproduction.