What Is Spina Bifida? What Causes Spina Bifida?
Spina bifida is a congenital malformation in which there is something wrong with the bone in the vertebral column, exposing the spinal cord which should be protected within the vertebral column. It is caused by the incomplete closing of the embryonic neural tube. Congenital malformation means a birth defect.
The central nervous system includes the brain, nerves and spinal cord. The spinal cord consists of nerve cells and nerve bundles that connect every part of the body to the brain.
During the first month after conception, the embryo develops a primitive tissue structure known as the neural tube. Gradually, this structure develops into bones, nerves and tissue which eventually form the nervous system and spine. When the unborn baby has spina bifida something goes wrong with the neural tube and spinal column development - it does not close fully. The spinal column is a ridge of bone that protects and surrounds the nerves.
The word Spina Bifida comes from the Latin "spina" meaning spine, and "bifida" meaning split.
There are three main types of spina bifida:
- Spina bifida occulta
- Spina bifida meningocele
Myelomeningocele - the most serious type and affects approximated 1 in every 1,000 babies born. Along several vertebrae the spinal column remains exposed. A sac forms on the baby's back as the membranes and spinal cord push out. The sac may be covered with meninges (membranes). The nervous system is more susceptible to infections, some of which can be life-threatening. Although surgery can correct the defect, it cannot reverse the extensive damage that has already occurred. The baby can have partly or totally paralyzed legs, urinary and/or bowel incontinence, and can lose sensation of the skin.
The majority of patients have excessive CSF (cerebrospinal fluid) - a condition known as hydrocephalus. CSF is a watery fluid which flows through the cavities (ventricles) inside the brain and also around the surface of the brain and spinal cord. In cases of babies with spina bifida, the accumulation of CSF is caused because the neural tube did not develop properly. The Hydrocephalus can result in brain damage, so the built up pressure needs to be alleviated by surgery.
As treatment options have improved, so has the outlook for babies with spina bifida. About fifty years ago the majority of babies would not survive beyond their first twelve months. Nowadays, most patients survive well into adulthood. A considerable number of adults with spina bifida can live independently.
What are the signs and symptoms of spina bifida?If the opening occurs at the top of the spine, the patient's legs are more likely to be completely paralyzed, and there will be other problems with movement elsewhere in the body. If the openings are in the middle or the base of the spine, symptoms tend to be less severe.
Myelomeningocele - the most severe form of spina bifida. Those with hydrocephalus have a greater chance of having learning problems.
Cognitive symptoms - problems occurring in the neural tube have a negative effect on brain development. The main part of the brain (cortex), especially the frontal part does not develop properly, leading to some cognitive problems. Cognitive refers to cognition; the process of awareness, thinking, learning, judging and knowing.
There may also be Type 2 Arnold-Chiari malformation, an abnormal brain development involving the cerebellum - this may affect the patient's language processing and physical coordination skills.
Approximately 60% of people with spina bifida will have average intelligence. A significant percentage of those with normal intelligence will have some kind of learning disability which may include problems with attention, solving problems, reading, understanding spoken language, making plans, and grasping abstract concepts. There may also be problems with visual and physical coordination, such as doing up buttons or shoelaces.
Most patients have some degree of paralysis in their legs. In cases of partial paralysis, leg braces or a walking stick may be necessary. When paralysis is total, the patient will need a wheelchair. If the lower limbs are not exercised they can become weak, which can eventually lead to dislocated joints, misshapen bones and scoliosis (the spine curves abnormally).
Most patients have bowel and urinary incontinence.
Spina bifida occulta - this is the mildest form. Most patients have no neurological signs or symptoms. There may be a small birthmark, dimple or tuft of hair on the skin where the spinal defect is. A considerable number of patients with this type of spina bifida never know they have it until an imaging test taken for another reason is done.
Myelomeningocele (open spina bifida) - the spinal cord develops normally, the meninges (protective membranes around the spinal cord) push through the opening in the vertebrae. The membranes are surgically removed, usually with no damage to nerve pathways, or very little damage.
What are the causes of spina bifida?Nobody is completely sure what causes spina bifida. Scientists say most likely it is due to a combination of inherited (genetic), environmental and nutritional factors.
Women who do not have enough folic acid during the pregnancy have a higher chance of giving birth to a baby with spina bifida. Experts say that women of reproductive age should make sure their folic acid intake is adequate. Nobody is sure how folic acid intake prevents spina bifida from developing.
If a woman gives birth to a baby with spina bifida, she has a higher-than-normal risk of having another baby with spina bifida too (about 5% risk).
Some medications, such as some for treating epilepsy or bipolar disorder have been associated with a higher risk of giving birth to babies with congenital defects, such as spina bifida.
Women with diabetes are more likely to have a baby with spina bifida, compared to other females.
Obese women, those whose BMI (body mass index) is 30 or more have a higher risk of having a baby with spina bifida. The higher the woman's BMI is over 30, the higher the risk.
Testing for and diagnosing spina bifidaIn the majority of cases, spina bifida is detected when the pregnant mother has a routine ultrasound scan.
Pregnant women may be offered spina bifida and other birth defect screening tests. The tests are not 100% accurate.
MSAFP (maternal serum alpha-fetoprotein) test - this is a blood test. Blood is sent to the lab and tested for AFP (alpha-fetoprotein). AFP is a protein the fetus produces. AFP does not usually get into the mother's bloodstream, if it does it usually means the fetus has abnormally high levels and probably has a neural tube defect, which could include anencephaly (incomplete skull and underdeveloped brain) or spina bifida. Some fetuses can have spina bifida and normal AFP levels. Even when a high AFP level is detected, most babies are eventually born healthy. If AFP levels are high, the doctor will order another blood test. If they are still high, further tests including an ultrasound scan will be ordered.
Other tests are performed during a woman's pregnancy, sometimes called a triple screen or quadruple (quad) screen.
If AFP levels are high an ultrasound scan can help the doctor determine why. Sometimes a high AFP level could be because the mother is carrying more than one baby, or everybody had miscalculated gestational age. An ultrasound scan can detect signs of spina bifida.
If the ultrasound reveals nothing abnormal, but AFP levels are high, the doctor may recommend amniocentesis. A sample of fluid is removed from the amniotic sac and tested for AFP levels. Fetuses with neural tube defects will have elevated AFP levels in the amniotic fluid that surrounds them. If tests show that AFP levels are high, the doctor will carry out another test to confirm.
What are the treatment options for spina bifida?Treatment depends on several factors, mainly how severe the individual's signs and symptoms are. In most cases of spina bifida occulta, no treatment is needed.
Surgery - if surgery is needed, this is usually done to repair the spine within two days of birth. The surgeon replaces the spinal cord and any exposed tissues or nerves back into the patient's body. The gap in the vertebrae will then be closed and the spinal cord sealed with muscle and skin.
If the child develops problems with bone development, such as scoliosis or dislocated joints, further corrective surgery may be needed (orthopedic surgery). For scoliosis a back-brace may be used.
Hydrocephalus - surgery will be required to treat a buildup of CSF (cerebrospinal fluid) in the brain. The surgeon implants a shunt (thin tube) in the baby's brain. The shunt drains away excess fluid, usually to the abdomen. The patient will probably need a permanent shunt. Further surgery may be needed if the shunt becomes blocked or infected, or a larger one is needed as the child grows.
Physical therapy (UK: physiotherapy) - this is a vital part of the child's treatment, which will help him/her become as independent as possible, as well as preventing the lower limb muscles from weakening. Special leg braces may help keep the muscles strong.
Prenatal surgery - the surgeon opens the uterus and repairs the unborn baby's spinal cord. This is usually done during week 19 to 25 of pregnancy. Because the risk of worsening spina bifida just after the baby is born, some experts say it is better to fix things beforehand. C-section birth - if the doctors and mother know the fetus has spina bifida, it will most likely be born by cesarean section (c-section), which is safer for the baby's exposed nerves.
Occupational therapy - the aim here is to help the child perform everyday activities more effectively, such as getting dressed. Occupational therapy helps with self-esteem and independence.
Assistive technologies - a patient with total paralysis of the legs will need a wheelchair. Although electric wheelchairs are more convenient, manual ones help maintain upper-body strength and general fitness. Those with partial paralysis may need leg braces. Computers and specialized software may help children with learning problems.
Urinary incontinence - the patient will probably be referred to a urologist for assessment.
- The child may be taught to use CIC (clean intermittent catherterization), a technique to empty the bladder at regular intervals in which the child and/or parent place the catheter through the urethra and into the bladder to empty it.
- The child may be prescribed antimuscarinics, medications used for urinary incontinence in adults - these medications increase the amount of urine the bladder can hold, thus reducing the number of times the child has to pee.
- If the child's bladder contracts abnormally (hyper-reflexic bladder), the doctor may recommend a botulinum toxin injection, which paralyzes the muscles. If it works, the patient will need repeat treatment every six months.
- Artificial urinary sphincter (AUS) - this is surgically implanted. It has a silicone cuff, surrounded by a liquid, a pump and a balloon. It is attached to the urethra and the balloon is placed in the abdomen. The pump is placed under the skin of the scrotum in males and under the skin of the labia in females. When the child wants to pee they press the pump, which temporarily empties the fluid from the cuff into the balloon, releasing th pressure on the cuff and opening the urethra, allowing urine to be released. Doctors say this device should not be used with younger boys (pre-puberty).
- Mitrofanoff procedure - the appendix is removed and a small channel is created (Mitrofanoff channel) which ends at an opening (stoma) just below the belly button. The child can place a catheter into the stoma to release urine and empty the bladder.
Anal plugs can prevent soiling. They are made of foam and inserted into the anus. As soon as it gets wet it expands, thus blocking the passage of any feces and liquid. Anal plugs work for about 12 hours, they can be taken out by pulling an attached string.
Children who have not responded to treatments may benefit from enemas - they clean out the bowel for two to three days.
Surgery for bowel incontinence - if none of the treatments worked properly, the doctor may recommend surgery. In an ACE (antegrade continence enema) the appendix is used to create a channel between the bowel and the abdomen - this channel ends at an opening (stoma) in the surface of the abdomen. If a catheter is inserted into the stoma, liquids can pass through the catheter, into the stoma and into the bowel to flush out its contents through the anus.
A colostomy involves diverting a section of the colon so that it connects to a stoma, which is attached to a pouch. The pouch collects stools. If the diversion is at the end of the small intestine the procedure is called an ileostomy.