Diseases and Disorders

Spina Bifida

Isha Saldhi


Introduction

Impacting 1,500 to 2,000 babies born in the United States annually, Spina Bifida is the most common defect of the neural tube caused by the incomplete development of an embryo’s neural plate[1]. Indications of Spina Bifida have been found by anthropologists going back to at least Hippocrates; however, the first description of the disease is found in the writings of Dr. Peter van Forest, a 16th-century physician [2]. This defect is classified into three types, Spina Bifida Occulta, Meningocele, and Myelomeningocele and is caused by an embryo’s lack of nervous system development [1]. There are many indicators of Spina Bifida before and after a baby’s birth [3].  Though there is no cure, Spina Bifida is a disease that has various methods of treatment. To ensure the health of a baby with Spina Bifida and prevent long-term complications, the disease should be treated a when a baby is born.

 

Classification and Symptoms

    People with Spina Bifida have an undeveloped neural tube. In a developing baby, the neural tube forms in the 4th week and then closes. If the neural tube does not close, there are malformations of the brain and spine [4]. Spina Bifida is classified into three different types based on the seriousness of symptoms: Occulta, Meningocele, and Myelomeningocele.

    Spina Bifida Occulta is a mild form of Spina Bifida and is the most common. It is found in 10 to 20 percent of the population, this variety rarely results in any disabilities or symptoms [1]. As seen in the first part of Figure 1, the malformation of the vertebrae is hidden under a layer of skin and sections of the vertebrae are not closed. Many different symptoms could arise on the skin at the site of the lesion. There could be an abnormal growth of hair, a dimple in the skin, a birthmark, or it could just appear normal. Most people with this type of Spina Bifida don’t recognize that they have it; it is generally asymptomatic [3].

    The least common form of Spina Bifida is Meningocele. In this classification, a meningeal cyst herniates from between the vertebrae. The protruding sac of fluid is made of protective membranes surrounding the spinal cord called meninges as seen in the middle of Figure 1 [3]. Not including parts of the spinal cord, this sac contains a low risk of nerve damage. Most people with Meningocele may have none or few symptoms, however, complications that could lead to paralysis or bladder and bowel dysfunction are possible [1].

    Myelomeningocele is the third and most severe form of Spina Bifida. Segments of the unfused spinal cord push through an opening creating a sac with meninges, cerebrospinal fluid, and other parts of the spinal cord and nerve roots [5]. Exposure of these tissues and nerves, as shown in the third part of Figure 1, makes the baby more prone to life-threatening infections [3].

    Myelomeningocele can cause complications such as the Chiari II malformation, hydrocephalus, and tethered cord syndrome. The Chiari II malformation which occurs when the brainstem and cerebellum protrude down into the spinal canal and neck. This sort of compression of the spinal cord causes symptoms such as difficulty in feeding, swallowing, breathing, choking, and stiffness or weakness in the upper arm. Another possible complication is called hydrocephalus, a buildup of cerebrospinal fluid which puts pressure on the brain and spinal cord. Additionally, tethered cord syndrome affects about 20 to 50 percent of children with Myelomeningocele which tethers the spinal cord to immovable structures such as membranes and vertebrae. This can cause the spinal cord to be stretched abnormally, resulting in muscle loss in the legs and changes to bowel and bladder function[1].

Figure 1: Types of Spina Bifida

    General problems that can be caused by Spina Bifida also include bladder incontinence, urinary tract infections, poor kidney function, hip dislocation, scoliosis, pressure sores, skin irritation, abnormal eye movement, and latex allergies [1].

 

Causes and Risk Factors

     Spina Bifida is caused by genetic and environmental factors. Deficiency of folic acid plays a key role in the source of Spina Bifida [1]. Other risk factors are the mother taking anti-seizure medication, being obese, and having diabetes. Any of these things can disrupt the closure of the neural tube [3]. Anti-seizure medications are thought to interfere with the body’s usage of folic acid. If there is a family history of neural tube defects, then the baby is thought to be at a higher risk of developing Spina Bifida. If a couple has had one child with the defect or the parents have the defect, the next child is at a 4 percent higher chance of being affected [3]. If the mother has increased body temperature in the early weeks of the pregnancy, there is an increased risk of the baby getting Spina Bifida [3]. The disease is more likely to develop in females than males and affect those of White and Hispanic heritage [3].

 

Diagnostic Methods

     Although Spina Bifida is mostly diagnosed prenatally, it can also go unnoticed until after birth. Prenatal diagnosis occurs in the second trimester around 16 to 18 weeks of gestation. Maternal serum alpha-fetoprotein (MSAFP) screening measures the protein levels of alpha-fetoprotein (AFP) which is made by the fetus and placenta [1]. Normally, small amounts of AFP enter the mother’s bloodstream; however, if the baby has Spina Bifida, abnormally high levels of the protein will be found in the mother’s bloodstream. This test is not definitive and if high levels are found then the doctor may request an ultrasound or amniocentesis to determine the cause. The MSAFP screening can also be done as a pet for a multiple-marker test looking for chromosomal abnormalities [1]. Amniocentesis can be used to diagnose Spina Bifida, the doctor would extract a sample of fluid from the amniotic sac. High levels of AFP and other proteins detected in the fluid would be indicative of Spina Bifida, however, the severity of Spina Bifida cannot be determined with this method [1].

    Mild cases of Spina Bifida, such as Occulta, are not diagnosed prenatally but can be detected postnatally by X-Ray [1]. Deformities can also be present in the feet, hips, and legs, where individuals with Spina Bifida have muscle weakness. In order to get a clearer view, doctors can use MRIs or CT scanning. If the doctor suspects hydrocephalus, a CT or X-Ray can be taken to look for excess cerebrospinal fluid in the brain [1].

 

Prevention

    Prevention of neural tube defects can be aided by folic acid supplements. Daily dosages of 0.4 mg of supplements are associated with a 36 percent risk reduction. However, with a 4 mg dose of folic acid per day, the chances of risk reduction are increased up to 70 percent [5]. All women in reproductive years should take periconceptional supplements for the best chance of preventing neural tube defects [5]. Since the embryo’s neural tube closes by 28 days from conception, preventative folic acid is not effective after the fourth week. Folic acid treatment is required for three weeks, therefore the best prevention is before conception. Ideally, folic acid supplements should be taken preferably two to three months prior to conception. Other than taking supplements, eating foods that are high in folic acid is recommended for women of childbearing age. Such foods are dark green vegetables, certain fruits, and egg yolks. There are some foods that are fortified with folic acid such as particular cereals, bread flours, pasta, rice and grain products [1].

 

Treatment

     Although there is no cure for Spina Bifida as the damaged nerve tissue cannot be completely repaired or have its’ function restored, there are several treatment methods that vary depending on the form of the disorder. The mildest forms of the disease do not require treatment, however, if they continue to grow then they may require surgery. Myelomeningocele should be treated early in order to prevent infection due to the nerves and tissue being exposed [1]. Children born with Spina Bifida can have surgery to close the spinal cord and minimize infection and trauma risk. Some medical centers perform fetal surgery in utero. This procedure involves making an incision in the mother’s abdomen and uterus and then sewing the opening in the baby’s spinal cord shut, as seen in Figure 2 [1]. The surgery is thought to be more effective when done in the early phase of fetal development, however, the neurological function cannot always be restored. Though this surgery is occasionally an option, it is still considered experimental and is associated with risks such as premature delivery, organ immaturity, brain hemorrhage, and death [1]. The mother is also at risk of infection, blood loss, gestational diabetes, and weight gain. Despite the risks, the surgery is still beneficial as it would minimize the exposure of the spinal nerve tissue and bone to the outside environment and toxic substances.

Figure 2: Fetal Surgery for Myelomeningocele

    Doctors have also discovered that this procedure could change the way the hindbrain develops in utero, and it could decrease the harm of complications such as Chiari II and hydrocephalus as seen in Figure 3 [1]. Surgery can also be performed on a tethered spinal cord in order to allow a child to gain function and prevent further neurological deterioration. Having surgery to place a shunt can alleviate the symptoms of hydrocephalus’ fluid buildup [Figure 3]. Occasionally, individuals may require additional surgeries to replace shunts that are outgrown or become clogged or infected [1].

Figure 3: Treatment for Myelomeningocele

    Individuals with Spina Bifida may be in need of assistive devices such as braces, crutches, or wheelchairs [1]. Depending on the location of the malformation on the spine, children will need different types of assistive devices. Higher defects will have more extensive symptoms and paralysis and will require a wheelchair on some occasions. Bladder and bowel problems begin after birth and may need to be managed with bladder catheterizations and bowel regimens. Those with lower defects will be in need of crutches, leg braces, or walkers. If the child exercises the legs and feet at an early age, they will be more prepared to walk with braces or crutches later in life.

    Since Spina Bifida is a common disease, learning about the symptoms is important to get sufficient treatment for the disease before the malformation can result in other complications. The way to ensure a child’s safety is to test for the disease when the fetus is in utero.


References


  1. Types of Spina Bifida [Digital image]. (n.d.). Retrieved August 1, 2018, from https://www.schn.health.nsw.gov.au/fact-sheets/spina-bifida

  2. Treatment for Myelomeningocele [Digital image]. (n.d.). Retrieved August 1, 2018, from https://fetus.ucsf.edu/spina-bifida

  3. Fetal Surgery for Myelomeningocele [Digital image]. (n.d.). Retrieved August 1, 2018, from https://fetus.ucsf.edu/spina-bifida

  4. Myelomeningocele: MedlinePlus Medical Encyclopedia. (n.d.). Retrieved August 1, 2018, from https://medlineplus.gov/ency/article/001558.htm

  5. Cavalli, P. (2008, December). Prevention of Neural Tube Defects and proper folate periconceptional supplementation. Retrieved August 1, 2018, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3279093/

  6. Spina bifida. (2018, March 09). Retrieved August 1, 2018, from https://www.mayoclinic.org/diseases-conditions/spina-bifida/symptoms-causes/syc-20377860

  7. Kennedy, F., & Wells, L. (2014, October 30). The History & Future of Spina Bifida. Retrieved August 1, 2018, from http://spinabifidanaturally.com/the-history-future-of-spina-bifida/

  8. Spina Bifida Fact Sheet. (2013, June). Retrieved August 1, 2018, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Spina-Bifida-Fact-Sheet

Isha Saldhi

Isha Saldhi


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