Spina bifida.

Spina bifida is the most common central nervous system birth defect encountered by the pediatric neurosurgeon. It is defined by characteristic development abnormalities of the vertebrae and spinal cord and associated changes in the cerebrum, brainstem and peripheral nerves. The expression of spina bifida encompasses the entire central nervous system, ranging in severity from merely an absent spinous process with normal intraspinal structures to the other extreme of myelomeningocoele, Chiari malformation, hydrocephalus, and cortical cytoarchitectural changes. Most children with myelomeningocoele have some degree of weakness of their lower extremities and many have significant orthopaedic problems. As a result of denervation, muscle imbalance ensues and can result in abnormalities at the hip, knee and foot. Anesthesia of various portions of the skin can lead to pressure sores, particularly later in life. Anorectal neuropathy may cause a variety of defecatory dysfunctions. Urologic abnormalities are also common. These multisystem abnormalities associated with spina bifida contribute to its widely accepted identity as the most complex development defect compatible with long life.