Myelomeningocele is a birth defect affecting the spine and spinal cord. It is a type of neural tube defect, occurring when the neural tube, which develops into the brain and spinal cord, does not fully close during early pregnancy. The “sac” refers to a visible protrusion on the baby’s back, containing parts of the spinal cord and nerves.
Understanding Myelomeningocele
Myelomeningocele is the most severe form of spina bifida, where the spinal canal remains open along several vertebrae. This opening allows the spinal cord and nerves to protrude through the back, typically encased within a fluid-filled sac. The sac usually contains the spinal cord, its protective coverings (meninges), and cerebrospinal fluid.
Exposure of the spinal cord and nerves within this sac leads to damage. The location of the myelomeningocele along the spine directly influences the severity of neurological impairment, with higher defects causing more extensive nerve damage. This damage can result in weakness, loss of sensation, or paralysis in parts below the level of the defect.
Causes and Prevention
Myelomeningocele arises from a combination of genetic predispositions and environmental factors. An insufficient intake of folic acid during early pregnancy is a preventable risk factor. Folic acid, a B vitamin, is important for proper neural tube development.
Healthcare guidelines recommend that women considering pregnancy take a daily supplement of 400 micrograms (0.4 mg) of folic acid. This should begin at least one month before conception and continue through the first 12 weeks of pregnancy, as the neural tube closes within the first month of gestation. For women with a higher risk, such as those with a family history of neural tube defects, diabetes, or those taking certain anti-seizure medications, a higher dosage of folic acid, 5 milligrams, is advised.
Diagnosis and Immediate Care
Myelomeningocele can be detected both before and after birth. Prenatal diagnosis often involves a combination of screening methods, including maternal serum alpha-fetoprotein (AFP) testing, performed between 15 and 18 weeks of gestation, and detailed ultrasound examinations. Ultrasound scans, particularly between 18 and 22 weeks, can reveal the spinal defect and sometimes associated signs like a lemon-shaped skull or abnormal cerebellar appearance. Amniocentesis, testing amniotic fluid, may also be used to confirm a suspected diagnosis.
Upon birth, immediate medical attention focuses on protecting the exposed sac to prevent infection and injury. Surgical repair to close the opening in the baby’s back is performed within 24 to 48 hours after delivery. This prompt surgery aims to prevent further neurological damage and reduce the risk of serious complications, such as meningitis. In some instances, prenatal surgery to repair the defect has been shown to improve outcomes by reducing the exposure of neural tissue to amniotic fluid.
Long-Term Management and Associated Conditions
Individuals with myelomeningocele often face associated medical conditions and complications due to nerve damage. Hydrocephalus, cerebrospinal fluid buildup in the brain, is common, often requiring the surgical placement of a shunt to drain excess fluid and relieve pressure. Chiari malformation, where brain tissue extends into the spinal canal, can also be present, potentially causing problems with breathing, swallowing, and arm weakness.
Bladder and bowel dysfunction are challenges because the nerves controlling these functions are often affected. Management may involve toileting routines, medications, or surgical interventions to promote bladder and bowel health. Mobility challenges, including muscle weakness or paralysis in the legs, are common, often necessitating assistive devices such as braces, crutches, or wheelchairs. Orthopedic issues like scoliosis (curvature of the spine), hip problems, and foot deformities may require ongoing orthopedic care or surgery.
Skin issues, including pressure sores, can develop due to reduced sensation and mobility, requiring monitoring and skin care practices. Some individuals may also experience learning differences or developmental delays, necessitating educational support and specialized therapies. Lifelong, multidisciplinary care is required, involving various specialists including neurosurgeons, urologists, orthopedists, physical therapists, occupational therapists, and educational professionals. This comprehensive approach aims to manage challenges, minimize complications, and support individuals in maximizing independence and quality of life.