Spina Bifida | Copp | Author manuscript | 2016
Spina bifida is a birth defect in which the vertebral column is open (bifid), often with spinal cord involvement. Clinically most significant is myelomeningocele (MMC; open spina bifida) in which the spinal neural tube fails to close during embryonic development. The exposed neural tissue degenerates in utero, resulting in neurological deficit that varies with level of the lesion. Occurring in around 1 per 1000 births worldwide, MMC is one of the commonest congenital malformations, yet its causation is largely unknown. The genetic component of MMC is estimated at 60-70% but few genes have yet been identified, despite much information from mouse models. Non-genetic risk factors include reduced folate intake, maternal anticonvulsant therapy, diabetes mellitus and obesity. Primary prevention by peri-conceptional folic acid has been demonstrated in clinical trials, leading to food fortification programmes in many countries. Prenatal diagnosis is by ultrasound enabling termination of pregnancy. Individuals who survive to birth have their lesions closed surgically, with subsequent management of associated defects, including the Chiari II malformation, hydrocephalus, and urological and orthopaedic sequelae. Fetal surgical repair of MMC has been associated with improved early neurological outcome compared with postnatal operation. MMC affects quality of life during childhood, adolescence, and into adulthood, posing a challenge for individuals, families and society as a whole.