Spina bifida is a birth defect where the vertebral column is open, often involving the spinal cord. The most clinically significant form is myelomeningocele (MMC; open spina bifida), where the spinal neural tube doesn't close during embryonic development. This leads to exposed neural tissue degenerating in utero, causing neurological deficits that vary based on the lesion's level.
MMC occurs in about 1 per 1000 births worldwide, making it one of the most common congenital malformations. The exact cause remains largely unknown.
The genetic component of MMC is estimated at 60-70%, but only a few genes have been identified. Non-genetic risk factors include reduced folate intake, maternal anticonvulsant therapy, diabetes mellitus, and obesity.
Primary prevention with peri-conceptional folic acid has shown positive results in clinical trials, leading to food fortification programs in many countries.
Prenatal diagnosis is possible via ultrasound, which can lead to pregnancy termination. Those who survive to birth undergo surgical closure of their lesions and management of associated defects like the Chiari II malformation, hydrocephalus, and urological and orthopedic sequelae.
Fetal surgical repair of MMC has shown improved early neurological outcomes compared to postnatal operations.
MMC affects the quality of life throughout childhood, adolescence, and adulthood, posing challenges for individuals, families, and society.
Epidemiology:
Spina bifida is a result of the failed closure of the embryonic neural tube. In its most severe form, myelomeningocele (MMC), the spinal cord is open dorsally.
Individuals with MMC often exhibit motor and sensory neurological deficits below the lesion level. This can lead to lower limb weakness or paralysis, lack of sensation, urinary and fecal incontinence, hindbrain herniation (Chiari II malformation), hydrocephalus, and orthopedic abnormalities.
The lifetime cost of a child born with MMC is estimated at over €500,000 ($600,000), with 37% being direct medical costs. The rest includes special educational and caregiver needs and loss of employment potential.
Risk Factors:
Both genetic and non-genetic factors contribute to Neural Tube Defects (NTDs). The genetic risk component is estimated at 60-70%. Fewer than 10% of NTD cases are syndromic, with the majority being non-syndromic and exhibiting a sporadic pattern.
Non-genetic factors include diminished folate status, maternal obesity, and exposure to various environmental factors. However, many of these factors are either inconsistently observed, infrequent, or don't have a large associated risk magnitude.
