Spina Bifida

Overview of Spina Bifida

Birth defects are on a steady rise due to the increasing burden of environmental and associated factors. Among the several reported cases of congenital defects, neural tube defects are common. At present they are affecting millions of children all over the world. People having a familial history of these disorders are 5-10 times more likely to develop neural tube defects than the rest. Spina bifida is one such neural tube defect that affects the spine.

Nearly 5% of the newborns suffer from a particular variant of spina bifida known as spina bifida occulta. With the major technological advancement in the medical field, the occurrence of these diseases can be detected in the pregnancy period itself. Therefore, matters like the continuation of the pregnancy and the associated risks should be consulted with a doctor.

What is spina bifida?

Spina bifida is a type of neural tube defect characterized by incomplete closure of the backbone and the membrane surrounding the spinal cord. In non-medical terms, it means “split spine”. A gap or split in the spine is observed in this case. This arises from a poorly formed spinal cord and vertebral bones. It usually occurs during the first four weeks of pregnancy. It is a congenital disorder.

The newborns with spina bifida generally have lesion(s) on their spinal cord. These lesions are the sites of damage to the spinal cord and the associated nerves. Numerous complications may stem from this disease. The most important one is paralysis of the lower limbs which depends on the exact location and severity of the lesion. In certain cases, no prominent lesion is observed. But the child may be born with a missing vertebra and may have severe nerve damage.

What causes spina bifida?

The exact etiology of spina bifida is still not established. Several research studies in the recent years have proposed certain theories that may explain the complications. It is typically regarded by some neurologists as a multifactorial birth defect. This implies that the disease is attributed to multiple factors like genetic, environmental and dietary factors.

Recent studies have shown that the paucity of folic acid (Vitamin B₉) in the diet of pregnant women can increase the risks of the disease. It is therefore advisable that the women of childbearing age should consume 0.4 mg of folic acid daily, or at least 3 months before pregnancy. Women with a history of childbirth with neural tube defect should consume 4.0 mg of folic acid every day before her next pregnancy.

Alcohol consumption increases the risks of macrocytosis, which discard the metabolism of folate in the body. This may eventually lead to neural tube defects. Even after the cessation of alcohol consumption, these women should allow enough time for the formation of healthy bone marrow. Studies have shown a demographic variation of the disease. Hispanics, particularly the Hispanic girls are more susceptible to the disease.

What are the main signs and symptoms?

The main physical manifestations include-

• Weakness of limbs
• Paralysis
• Orthopedic problems- scoliosis, clubfoot, hip dislocation
• Urinary incontinence- Kidney dysfunctions, urinary tract infection, lack of bladder control
• Bowel incontinence
• Skin irritations and rashes
• Pressure sores (ulcers)
• Abnormal eye movements
• Allergy to latex

Babies born with spina bifida have structural abnormalities of the cerebellum. Diagnoses reveal that the posterior portion of the brain is pushed from the back of the skull into the lower neck. The displaced cerebellum often interferes with the normal flow of the cerebrospinal fluid (CSF). In 70-90% of the patients, the corpus callosum is malformed. This leads to a disrupted coordination between the left and the right brain lobes.

The following neurological abnormalities are observed-

• Executive function: The affected children may face difficulties in planning, organizing and initiating an activity. They may also have a poor working memory and cognitive deficits. Some of these children may also have ADHD.
• Academic skills: The children may lack mathematical skills, which are mainly associated with the parietal lobe.

What are the different types of spina bifida?

Spina bifida has three subtypes.

• Spina bifida occulta: Nearly 15% of the affected people have this form but exhibit no symptoms. Hence it is also called “hidden spina bifida”. In this condition, the spinal cord and the surrounding structures remain inside the body. However, the backbones in the lower back region are poorly formed. A hairy patch or a slight dimple may be present at the site of the defect.
• Meningocele: It is a moderate form of spina bifida characterized by the presence of a fluid-filled sac outside the back. The sac does not contain the spinal cord or the nerves.
• Myelomeningocele: It is the most severe form of spina bifida where the spinal cord and the nerves develop outside the body. They mostly remain inside a fluid-filled sac that forms on the back. These children generally have a loss of sensation below the defect. Many of these babies have an accumulation of fluid inside their heads, a condition termed as “hydrocephalus”. It exerts immense pressure on the skull bones that eventually expand to an abnormally large size.

How can the disease be diagnosed?

The diagnosis of spina bifida can be done in the gestational period or after childbirth. Both the cases are discussed below-

• Prenatal diagnosis: The common screen test is the measurement of Maternal Serum Alpha-Fetoprotein (MSAFP).
• Postnatal diagnosis: X-ray, CT scan, and MRI scan can reveal abnormalities in the spinal cord and the skull.

Is it possible to treat spina bifida?

The treatment mainly involves surgery (prenatal or postnatal). Prenatal surgeries are performed by surgically exposing mother’s uterus before the 26^th week of pregnancy. Fetal surgeries reduce the extent of disability the child might have after birth. Cesarean birth is sometimes a safer way to deliver in case the fetus has myelomeningocele.

Treatment is also required for the complications arising due to spina bifida. Walking and mobility aids such as crutches, braces, walkers, wheelchairs etc. can help the child to walk and move around. Children facing difficulties in bowel management can be given oral medications, suppositories, and enemas. Surgical intervention or a combination of two or more methods can be opted based on the condition. Bladder management is done by the use of medications or catheters.

Though the exact reason behind the neural tube defect is unknown, prevention of spina bifida is possible to a certain extent by focussing on the diet and overall health of the expecting mother. A balanced diet rich in folate and other nutrients is essential.

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