Myelomeningocele

Excerpt

Myelomeningocele is a severe neural tube defect caused by incomplete closure of the spinal cord during early fetal development, typically within the first month of gestation. This condition is a form of open spinal dysraphism or spina bifida aperta. Myelomeningocele is characterized by an exposed spinal cord and meninges that protrude from the vertebral column, which is evident during a physical examination. In contrast, closed spinal dysraphism, or spina bifida occulta, consists of skin-covered lesions that may not be immediately noticeable except for common cutaneous findings such as hemangiomas, hypertrichosis, sacral dimples, or subcutaneous lipomas.

Myelomeningocele is associated with significant neurological impairments that vary depending on the location of the lesion along the spine. Higher spinal lesions often result in more severe motor deficits, such as paraplegia, while lower lesions primarily cause weakness, sensory loss, and bladder or bowel dysfunction. As a result, the prognosis is generally worse if a myelomeningocele is diagnosed late or left untreated.

Risk factors for myelomeningocele include environmental exposures, maternal health issues, inadequate pre-pregnancy folic acid intake, and genetic predispositions, including chromosomal abnormalities such as trisomy 18 or 13. Common complications include neurogenic bladder, renal problems, and concurrent conditions, such as Chiari II malformation and hydrocephalus, which worsen morbidity and mortality. Fetal diagnosis can be made through elevated maternal serum alpha-fetoprotein levels and ultrasonography, which reveal characteristic cranial and spinal signs. Management involves early postnatal surgical closure or prenatal repair to reduce complications, such as hindbrain herniation. Treatment may also address associated hydrocephalus and Chiari II malformations through shunt placement or endoscopic surgery, aimed at preventing further neurological decline and promoting optimal development.