Newborn Spine Deformities

Identification and Treatment in Early Life

In few instances, prompt identification and early surgical intervention is crucial to life. This is particularly true for diagnoses such as myelomeningocele, where early coverage of the defect, ideally within the first few days of life, is important to minimize the risk of infection and further neurologic damage. In some selected centers, fetal surgery can be performed in utero for myelomeningocele, which offers a rare, albeit investigational, opportunity to potentially improve the outcome for the developing patient. ^, However, most cases of spinal deformity are surgically addressed later in infancy or early childhood.

Early childhood intervention may be recommended due to the progressive nature of the deformity and the subsequent neurologic, respiratory, or even vascular complications that can ensue from the deformity. The main goal of orthopedic surgical intervention is to maximize function and independence. For the vast majority cases, this is directly related to the level of neurologic involvement. The timing of surgical interventions must be carefully balanced in regard to the patient's growth potential. Despite an ever-expanding variety of growth-friendly surgeries, relative equipoise remains on when to best operate on the spine that requires early intervention—many patients begin with serial nonoperative interventions in an attempt to delay surgery as much as reasonable prior to early surgery on the fewest vertebrae possible.

Appraisal Literature and Evidence-Based Guidelines

Spina bifida, in comparison with other neonatal spine deformities, is a more common deformity, so there is good literature regarding its natural history, evaluation, assessment, and management. However, for the remaining less common neonatal deformities, there are usually several accepted options for management ( Table 72.1 ). Unfortunately, there are few high-level studies regarding most neonatal spinal deformities. This is partially due to the relatively low incidence of each disorder and the heterogeneity present within each disorder.

There is often high-level evidence about the natural history of newborn spine deformity. ^{, , ,} Historically, most treatment studies are of evidence level four or five, with the rare level-three evidence study. With the advent of growth-friendly surgical techniques and the relatively new opportunity to compare long-term outcomes, there is now a growing number of level-two evidence studies in the literature. ^, With continued advancement of our knowledge of spinal development and the emergence of new techniques, so too will evidence emerge to improve management of this complex and diverse patient population.

Embryologic Development of the Spine ^,

At approximately the gestational age of 20 days, the neural plate folds to form the neural tube. As the lateral-edge closure proceeds both cranially and caudally toward each neuropore, the neural tube is effectively pinched off from the epidermis. The cranial neuropore closes at about day 24; the caudal neuropore, day 28. The neural tube will go on to develop as the spinal cord and the rest of the central nervous system. The notochord persists as the nucleus pulposus in intervertebral discs.

In somitogenesis, the paraxial mesoderm condenses in pairs on either side of the notochord. Each somite gives rise to a ventral sclerotome and a dorsolateral dermomyotome. In the fourth week of gestation, a portion of each sclerotome migrates ventrally to fully engulf the notochord. Ventrally migrated cells will go on to form the vertebral body; the dorsal cells will form the vertebral arch and costal processes. The cranial half of one sclerotome and the caudal half of the adjacent sclerotome fuse, each contributing a portion of cells to the development of a single vertebra. Thus a single vertebra results from the proper formation and migration of cells from two somite levels.

During the first year of life, the vertebral arches join together. The arches then go on to join the vertebral bodies, beginning cervically at about 3 years of age and completing distally by 6 years of age.

Environmental Etiology of Spinal Malformations

Maternal exposure to medications or toxins such as carbon monoxide, alcohol, boric acid, and/or valproic acid may cause congenital scoliosis. Aberrations in the developmental milieu have also been associated with vertebral malformations, hyperglycemia, hypoxia, and hyperthermia. However, in most cases, an individual cause cannot be found.

Similarly, it is also appreciated that the developmental milieu must also have sufficient presence of certain factors. The most notable of these is folic acid for proper neurulation. The decrease in incidence of infants born with neural tube defects has been attributed to prenatal screening and now widely accepted maternal perinatal supplementation. In populations where perinatal supplementation is limited and where the cultural diet contains less enriched foods, incidence of neural tube defects is higher.

Growth and Development ^,

The neonatal spine will nearly triple in length from birth to adulthood. The vertebral apophysis at the superior and inferior vertebral endplates contributes to two rapid growth periods—from birth to about 5 years of age and during puberty. Each thoracic vertebrae, of two apophyses per vertebrae, contributes approximately 1 mm per year to vertebral column height. The more rapid growth velocity is from birth to 5 years of age, when the spine gains about 10 cm in vertebral column length. The growth of the spine, thoracic cavity, and lungs is intimately associated. Significant disturbance of normal spinal growth or thoracic cavity development will impair pulmonary maturation, potentially severely decreasing pulmonary function.