The most common spinal anomaly is spina bifida, which occurs in several different forms varying in severity. Myelomeningocele is the open form of spina bifida, where the developing neural tube fails to close early in pregnancy, resulting in a portion of the incompletely developed spinal cord exposed through a skin defect on the back. Urgent surgery shortly after birth restores tissue coverage to the spinal cord, but cannot restore neurologic function. These infants also frequently have associated hydrocephalus (fluid on the brain), and Arnold-Chiari malformations (see below), requiring ongoing neurosurgical evaluation and treatment. In addition, the failure of the lower portion of the spinal cord to close results in bowel and bladder incontinence and orthopedic deformities, requiring other pediatric subspecialists often in a multidisciplinary spina bifida clinic setting. Due to the severity and life-altering nature of these deficits, there has been considerable interest in fetal surgery for the repair of myelomeningoceles in the uterus. A multi-center randomized trial (MOMS Trial) has shown encouraging results to this approach, although with significant risk to both mother and fetus.

Spina bifida occulta is a term that encompasses the closed forms of spina bifida, where the skin over the spine is closed, but a variety of malformations result in a tethered cord, in which the bottom portion of the spinal cord is attached to structures within the spinal canal or subcutaneous tissues. The simplest of these is the fatty filum terminale, in which the normal thin tail of the spinal cord is thicker and less elastic, allowing tension on the spinal cord as the child grows. A lipomyelomeningocele is a fatty mass, similar to a mushroom erupting from the bottom of the spinal cord, and blending into the normal fat beneath the skin. A lumbar dermal sinus tract is a dimple, which may indicate a tract extending, and attaching to the bottom of the spinal cord. A split cord malformation is a more complex malformation in which a spike of bone may between two halves of the spinal cord. All of these conditions may affect the function of the bottom portion of the spinal cord, causing pain, numbness, and weakness of the legs, as well as bowel and bladder incontinence. For this reason, these patients are also ideally followed in a multi-disciplinary spina bifida clinic.