Spina Bifida (SB) is a Neural Tube Defect (NTD) that occurs when the spine and spinal cord do not form properly during early pregnancy. The resulting damage to the nervous system often leads to physical impairments ranging from mild to severe. Therefore, spina bifida is classified as a physical disability, particularly in its more pronounced forms, due to its direct impact on an individual’s physical functioning, mobility, and independence.
Defining Spina Bifida and Physical Disability
Spina bifida originates from a failure of the neural tube to completely close, a process that typically concludes by the 28th day after conception. This incomplete closure prevents the protective backbone from fully forming, potentially leaving the spinal cord and nerves exposed and damaged. The severity of the resulting physical limitations depends directly on the location and extent of this damage along the spine.
A physical disability is defined as a condition causing a substantial limitation in one or more major life activities, such as walking, standing, or performing manual tasks. The Americans with Disabilities Act (ADA) uses this definition to determine eligibility for protection against discrimination. The functional limitations caused by spina bifida, particularly those affecting movement and bodily control, meet these criteria.
The Social Security Administration (SSA) acknowledges that the symptoms and complications caused by spina bifida may prevent individuals from engaging in substantial gainful activity as adults. While the condition itself does not automatically guarantee disability benefits, the resulting functional limitations, such as mobility problems or neurological impairments, qualify for consideration.
Spectrum of Physical Impairment: Types of Spina Bifida
The physical impact of spina bifida is highly variable, existing on a spectrum defined by three primary types. The severity hinges on whether the spinal cord and nerves protrude through the opening in the vertebrae. This structural difference determines the extent of neurological damage and subsequent physical limitation.
The mildest and most common type is Spina Bifida Occulta, where a small gap exists in the vertebrae, but the spinal cord and nerves remain protected and undamaged. Because the nerves are unaffected, this form usually results in no symptoms and does not cause physical disability, often remaining undiagnosed until adulthood.
Meningocele is a rarer type where the meninges, the protective membranes surrounding the spinal cord, push through the spinal opening, forming a fluid-filled sac. Since the spinal cord itself is typically not involved, this form rarely causes significant physical disability, though minor issues with bladder or bowel function may occur. Surgical closure of the sac is performed to reduce the risk of infection.
Myelomeningocele represents the most severe type of spina bifida and is the primary cause of physical disability associated with the condition. In this form, a sac containing spinal fluid, meninges, and parts of the spinal cord and nerves protrudes through the opening in the back. The exposed nervous tissue is damaged, leading to pronounced and permanent physical impairments. This type causes moderate to severe disabilities, including a significant loss of movement and sensation below the level of the lesion.
Primary Physical Manifestations
The physical manifestations of myelomeningocele are directly related to the location of the spinal cord lesion, which determines the level of neurological function loss. A lesion higher on the spine, such as in the thoracic region, affects more nerves and results in more severe lower limb paralysis. Conversely, a lesion lower down the spine, such as in the sacral region, may allow for some walking ability, often with the aid of assistive devices.
Impaired mobility is a hallmark of severe forms, ranging from muscle weakness to complete paralysis in the legs and feet. Individuals with higher-level lesions often rely on wheelchairs, while those with lower-level lesions may use crutches, braces, or walkers. The resulting muscle imbalances and joint issues commonly lead to orthopedic complications, such as hip dislocation, scoliosis, and foot deformities, requiring multiple surgeries and ongoing physical therapy.
Another frequent physical manifestation is hydrocephalus, an excessive buildup of cerebrospinal fluid in the brain. This complication occurs in up to 90% of babies with myelomeningocele and requires the surgical insertion of a shunt. The shunt drains the fluid and relieves pressure on the brain, preventing neurological damage.
Damage to the nerves controlling the lower body also leads to a loss of bladder and bowel control, referred to as neurogenic bladder and bowel. The nerves regulating the detrusor muscle and sphincter function are interrupted, causing issues with both urine storage and emptying. This functional limitation requires proactive management, often involving clean intermittent catheterization (CIC) multiple times a day to empty the bladder and prevent kidney damage, alongside bowel management programs.
Causes and Preventative Measures
Spina bifida is a multifactorial condition, arising from a combination of genetic and environmental factors that disrupt the neural tube’s development. While the precise cause is not fully known, a lack of the B-vitamin folic acid in the mother’s diet is the most significant preventable risk factor identified. Since the defect occurs very early in pregnancy, often before a woman is aware she is pregnant, pre-conception nutrition is important.
Public health recommendations focus on increasing folic acid consumption among all persons capable of becoming pregnant. This preventative strategy is based on evidence showing that periconceptional folic acid supplementation can reduce the risk of neural tube defects by 50% or more. The U.S. Public Health Service recommends that all women capable of becoming pregnant consume 400 micrograms (0.4 mg) of folic acid daily.
For women who have previously had an NTD-affected pregnancy, the recommendation for folic acid intake is significantly higher, at 4,000 micrograms (4 mg) daily. This intake should start at least one month before conception and continue through the first trimester to reduce the incidence of these birth defects. The fortification of certain grain products with folic acid in many countries has also been a successful public health measure to increase baseline consumption.