Spina Bifida and Myelomeningocele

What Causes Spina Bifida?

The exact cause of spina bifida is unknown. There is support that many things may play a role in causing problems with the development of the neural tube, such as a mother’s abnormal nutrition or exposure to drugs, chemicals, or radiation before, during, and after the start of pregnancy (conception).

Genetic (inherited from family) factors may also contribute to the cause of spina bifida. However, most (95%) of children with spina bifida are born to parents with no family history of the disease. According to the American College of Obstetricians and Gynecologists (ACOG), parents with one child with spina bifida have about a 4% chance of having another child with the disease, and parents with two children with spina bifida have about a 10% chance of having another child with it. When one parent has spina bifida, they have about a 4% chance of having an affected child.1

What are the Types of Spina Bifida?

There are three major types of spina bifida:

Spina Bifida Occulta

Spina bifida occulta is the mildest form of spina bifida. It is a rather common condition, occurring in about 10-20% of people. It occurs when the bones of the spine (vertebrae) do not close completely. However, it typically does not affect the nerves or spinal cord, and most people with spina bifida occulta do not have any disabilities or nerve problems.

Sometimes people with spina bifida occulta can have complications that do affect the nerves of the spine. The most common problem that can occur with this form of spina bifida is a tethered spinal cord. This happens when the spinal cord becomes abnormally attached to the body, causing stretching of the cord.

Meningocele

The meninges are three layers of protective tissues that cover the spinal cord. A meningocele forms when the bones of the spine (vertebrae) do not close completely, and the meninges protrude in a sac through the hole that is formed. This sac is usually well covered with skin, and typically causes no problems. The spinal cord and nerves are not in the sac, and usually remain in the normal position within the spinal canal. However, occasional complications, such as tethering of the spinal cord, may occur.

Myelomeningocele

Many people use the words “myelomeningocele” and “spina bifida” interchangeably. Myelomeningocele is the most severe form of spina bifida.

What is Myelomeningocele?

Myelomeningocele is the most severe form of spina bifida, and occurs in about one-half to one out of every 1,000 pregnancies in the United States. It happens when the bones of the spine (vertebrae) do not close completely, and part of the spinal cord and meninges (protective tissues covering the spinal cord), contained within a sac-like membrane, protrude through the hole to the outside of the body. The parts of the spinal cord and nerves that are included in the sac are usually damaged or abnormal. However, the rest of the spinal cord and nerves remaining inside the spinal canal are typically normal. The effects on the nerves and spinal cord contained within the sac result in various disabilities, such as, inability to feel and move the legs and feet and inability to control urination and bowel movements. A myelomeningocele can form anywhere along the spine. The higher on the spine that one forms, the more severe the disabilities associated with it will be.

Problems Commonly Associated with Myelomeningocele

• Inability to feel the legs and/or feet (no sensation or “numbness”)
• Inability to move the legs and/or feet (paralysis)
• Disabled walking or inability to walk
• Stiff joints (contractures), especially in the hips, knees, and feet
• Clubfoot
• Developmental Dysplasia of the Hips (problems with formation of the hip joints)
• Scoliosis/Kyphosis (abnormal curvatures of the spine)
• Tethered spinal cord
• Hydrocephalus (too much spinal fluid in the brain)
• Chiari Malformation (an abnormal development of the brain)
• Inability to control urine or bowel movements

Diagnosis of Myelomeningocele

• Prenatal testing (testing of mother and unborn baby during pregnancy)
  • Alpha Fetal Protein testing of mother’s blood: This protein (AFP) may be found in the mother’s blood if she is pregnant with a baby that has a myelomeningocele.
  • Ultrasound (sonogram)
  • Amniocentesis (testing of the amniotic fluid that surrounds a baby during pregnancy)
• Exams of the baby after birth
  • Clinical (physical) exam findings
  • MRI (Magnetic Resonance Imaging)
  • CT (Computed Tomography or “CAT scan”)

How is Spina Bifida and Myelomeningocele Treated?

There is no cure for spina bifida. One of the first treatments for myelomeningocele is surgical closure of the opening of the spine, usually by a neurosurgeon. Further treatments are focused on supportive therapies, and the prevention and treatment of associated problems. The Orthopedic Surgery team of Nationwide Children's Hospital provides care for children with spina bifida and their families through the prevention and treatment of the musculoskeletal problems in patients with the disease, including abnormal spinal curvatures (scoliosis and kyphosis), joint contractures, clubfoot, hip abnormalities, and more. We are dedicated in working together with Physiatrists, Neurosurgeons, Urologists, Physical and Occupational Therapists, orthotists, and others in our multidisciplinary to Myelomeningocele Clinic to support and improve the health, mobility, and overall quality of life for these children and their families.

Additional information on Spina Bifida and prevention strategies can be found at:

• Centers for Disease Control and Prevention
• Spina Bifida Association of America
  1 (800) 621-3141
  sbaa@sbaa.org
• March of Dimes Birth Defects Foundation
  (914) 997-4488

Resources:

1. American College of Obstetricians and Gynecologists (ACOG). Neural Tube Defects. ACOG Practice Bulletin, number 44, July 2003 (reaffirmed 2008).