Spina Bifida: Overview
Definition
Spina bifida (SB) is a general term that includes a wide assortment of neural tube defects. It describes children with no neurological dysfunction, or those with mild to very severe paralysis and disability. Normally, the neural tube closes at about 25 days’ gestation. In spina bifida, however, there is an abnormal opening of the vertebrae posteriorly, and the cells that become the spinal cord do not develop properly. The spinal cord remains a flat plate of nerve cells as the neural tube does not close. Also there is emerging evidence that the exposed neurons die due to a toxic amniotic fluid environment that develops at about 34 weeks of gestation.
Occurrence and Statistics
In the United States, the prevalence of neural tube defects is .5 to .8 cases per 1,000 births. There is a higher recurrence rate for families with one child with a neural tube defect, and a 10% recurrence rate for mothers with two affected children. It is more frequent in China. In the United States, the prevalence of neural tube defects is higher now in Hispanic communities and lower in African American communities.
In the 1950s, the mortality rate for children born with spina bifida was 90%. However, in the 1960s with the addition of the shunt, the survival rate of the infant approached 90%. Today, around 166,000 individuals with spina bifida live in the U.S. Major issues that are faced are the transition to adult medical care, independent living, and social skills.
Detection and Prognosis
Spina bifida is detected in utero via amniocentesis and ultrasound. Associated conditions that may accompany spina bifida are ruptured sac after birth, meningitis, hydrocephalus, Chiari II malformation, kyphoscoliosis, intellectual disability, and urinary tract infection. The shunt is required for almost all children with thoracic spine level lesions, about 85% for those who have a lumbar level lesion, and about 70% with those with a sacral level lesion. In recent years, fetal myelomeningocele surgery has emerged, and the research is showing that it may have effects on neurological function, most notably reducing the need for a shunt placement. This surgery is typically completed between 19 and 25 weeks of gestation. At this time, the rate of survival to the age of 40 is 20% for those with a lesion above T11, and 60% for those with lesions at L3 and below.
Etiology
The etiology still is unknown. It is believed to have a hereditary component, as the prevalence rates of different ethnic groups do remain constant as they move from one place to another. Spina bifida is linked to lower levels of folate, as well as low vitamin C, serum vitamin B12, and low zinc intake. Spina bifida affects females more than males. Other maternal factors that may be linked to spina bifida are lower socioeconomic status, diabetes, obesity, infection, psychosocial stressors, smoking, and the use of alcohol, caffeine, and valproic acid. In addition, environmental factors such as pollution can increase the likelihood of having a child with a neural tube defect.
In the following diagram (Figure 1), in the top left, you will see a representation of a normal spine and spinal cord. In the top right could be a neurological disorder related to the malformation of the spinal cord. In the middle left is meningocele, where portions of the spinal cord push through, but nerves are not typically damaged, and then on the middle right side is myelomeningocele, where spinal cord and nerves do come through the opening in the spine, and there is nerve damage.
Figure 1. Normal spinal cord compared to spina bifida.
Special Care Needs
There are many areas where special care is needed for children and adolescents with spina bifida. Those include skin care, nutrition and weight management, latex and rubber allergy awareness, bladder management, bowel management, education and learning, as well as growing up and transitioning to adulthood.
