Spina bifida: A birth defect (a congenital malformation) in which there is a bony defect in the vertebral column so that part of the spinal cord, which is normally protected within the vertebral column, is exposed. People with spina bifida can suffer from bladder and bowel incontinence , cognitive (learning) problems and limited mobility.
The effects of myelomeningocele, the most serious form of spina bifida, may include muscle weakness or paralysis below the area of the spine where the incomplete closure (or cleft) occurs, loss of sensation below the cleft, and loss of bowel and bladder control. In addition, fluid may build up and cause an accumulation of fluid in the brain (a condition known as hydrocephalus). A large percentage (70%-90%) of children born with myelomeningocele have hydrocephalus. Hydrocephalus is controlled by a surgical procedure called “shunting,” which relieves the fluid buildup in the brain. If a drain (shunt) is not implanted, the pressure buildup can cause brain damage, seizures or blindness. Hydrocephalus may occur without spina bifida, but the two conditions often occur together.
A remarkable feature of malformations in vertebrates including man is the association of multiple abnormalities in complex syndromes. Thus, in man cleft lip, spina bifida, hydrocephalus, and polydactyly may be found in the same individual; acrocephalosyndactyly (an egg- or dome-shaped skull and partial or complete fusion of digits in both hands and feet) often occurs with harelip, contractures, spina bifida, and mental abnormalities.