Spina bifida (Myelodysplasia)

What is Spina bifida?

• Spina bifida is an umbrella term used to describe a wide variety of congenital defects in the spinal column of a fetus.

• It’s a type of open neural tube defect (ONTD) in which there’s an incomplete development of the back bones, spinal cord, surrounding nerves and/or the fluid-filled sac that surrounds the spinal cord.

• The deficiency can occur anywhere along the spine, and can cause a portion of the spinal cord and surrounding structures to develop outside the protection of the spinal column.  About 85 percent of the defects are found in the lower back, with the remaining 15 percent in the back of the neck or upper back.

What are the three main types of spina bifida?

Spina bifida occurs in three major types, each of which has varying degrees of severity:

Spina bifida occulta (hidden)

• The mildest form, in which there is no obvious sign of a malformation. There’s a gap least one of the bones in the spine (vertebrae), but the skin is intact and the nerves and spinal cord don’t protrude. The child may experience mild or no symptoms.

• In many cases, spina bifida occulta in children is not detected until an x-ray is done for an unrelated condition.

Meningocele

• A moderate form—and the least common—in which the membranes that cover the brain and spinal cord (meninges) protrude through a defect in the spinal column.  The spinal cord typically remains intact, which means that these meninges can be removed surgically with little risk of nerve damage.

• Lipomeningocele: a variation of meningocele in which a fatty mass (lipoma) is attached (tethered) to the spine and pulls on it. The child may or may not have much nerve damage; there may be urinary and bowel problems. Surgery can release the tethering.

Myelomeningocele

• The most severe and most common form of spina bifida in which the backbone and spinal cord fail to close. There’s no (or incomplete) skin formation over the area, and the spinal cord hasn’t developed normally.

• Children born with myelomeningocele are often fully or partially paralyzed below the defect and usually have difficulty with bladder and bowel control (incontinent). Nerve damage and other severe neurological impairments are also common.

Causes

What causes spina bifida?

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

The cause of spina bifida and other ONTDs remains unknown, but likely results from a combination of genetic, nutritional and environmental factors, such as:

• Deficiency of folic acid (a B vitamin) intake by the mother during pregnancy

• Taking enough folic acid at the time of conception and during pregnancy can reduce the risk. Folic acid is now a mandatory vitamin additive in cereals and some grain foods.

• Uncontrolled diabetes in the mother

• A high fever during early in her pregnancy

• More than 90 percent of cases occur without a prior family history of spina bifida. However, having one child with spina bifida increases the chance of having a second child with the same condition by 3 to 5 percent.

Signs and symptoms

What are the signs and symptoms of spina bifida?

The signs and symptoms of spina bifida vary widely, depending on the form of the condition and its severity in the individual child. At birth, the sign and symptoms for each form of the disease include:

• Spina bifida occulta: Since the spinal cord does not protrude through the skin, there may be no obvious signs or symptoms. However, there may be a small, hairy patch, dimple or birthmark on the lower spine.

• Meningocele: there will be a fluid-filled sac protruding along the back bone area, which can lead to a large mass on the back.

• Myelomeningocele: there will a sac-like mass of nerves and spinal cord that protrudes from the back.  This mass consists of meninges (membranes that cover the brain and spinal cord), portions of the spinal cord, and nerves. At birth, babies with myelomeningocele will have an open spinal defect which requires urgent surgery to close the skin and protect the spinal cord and nerves. 

In severe spina bifida, symptoms related to nerve damage in the lower spine include:

• Loss of sensation and movement in the legs and feet (paralysis)
• Poor bladder control (incontinence)
• Poor bowel control (constipation, incontinence)

Do children with spina bifida have other health problems?

Children with spina bifida may have associated health problems, including:

• Hydrocephalus: the blockage that occurs when spinal fluid builds up in and around the brain. This blockage creates pressure in the head and can cause headaches, nausea and vomiting. Hydrocephalus occurs in up to 90 percent of children with myelomeningocele. If left untreated, hydrocephalus can lead to serious illness and neurological problems, including brain damage.

• Chiari II malformation: an abnormality that occurs whenportions of the hindbrain, along with the brain stem itself, are pushed downward through the skull base opening and into the upper part of the spine.  This can cause pressure on the brain stem and disturbances in the circulation of cerebral spinal fluid, eventually leading to symptoms such as vocal cord weakness, swallowing disturbances, leg weakness and spinal deformities.  

• Orthopedic (bone) problems, including: can develop over time due to the imbalance of muscle strength. These include scoliosis, kyphosis, hip dislocation, joint deformities, clubfoot and weaker than normal bones.
   
• Tethered cord: a condition that occurs when a child’s spinal cord is abnormally attached (tethered) to the tissues around the spine. Tethered cord can cause a number of neurologic problems, such as weakness in the legs or feet, back pain, leg pain, problems controlling the bowels or bladder and spinal abnormalities.  

• Urinary tract infections (UTIs) or kidney malfunction.

• Latex allergies:children with spina bifida who have been exposed to latex due to frequent medical procedure have a high risk for developing a latex allergy.