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.

Spina Bifida

Spina bifida disorders, or myelodysplasias, are neural tube defects characterized by failure of formation, affecting the dorsal vertebral elements, and a defect of the overlying skin, allowing for exposure of the meninges and spinal cord. In the most common and most severely disabling form of spina bifida, myelomeningocele, examination reveals a protruding sac containing neural elements. With meningocele, the protruding sac does not contain neural elements. Lipomeningocele refers to an open distal lumbar bony canal with intact dermis and epidermis. There is fatty infiltration of the canal, often causing tether. Hydrocephalus is rare. In spina bifida occulta, despite an underlying defect in the vertebral arch, the meninges and cord are normal and the bony defect has no clinical significance.

In addition to intrinsic malformation, exposure of the spinal cord and nerve roots to the toxic amniotic fluid leads to neurogenic bladder, bowel dysmotility, and motor and sensory deficits below the level of the lesion. Asymmetry of sensory loss or weakness is common. Other lesions exist in conjunction with spina bifida that can affect neurologic function, including Chiari malformation, cerebellar hypoplasia, hydrocephalus, tethered cord, syringomyelia, or diastematomyelia. Congenital manifestations of spina bifida including kyphosis, scoliosis, hip dislocation, clubfoot, or vertical talus are often present at birth and can worsen with development. Additional musculoskeletal pathology such as contracture, bony deformity, fracture, and wounds may develop with time due to chronic muscular imbalances, disuse osteopenia, paralysis, and sensation deficit.

Congenitally Abnormal Vertebrae ^{, , , , , ,}

Congenitally abnormal vertebrae collectively describe abnormal bony development seen in congenital scoliosis, congenital kyphosis, rib and scapular fusions, clefted vertebrae, and vertebral agenesis. Three basic types of vertebral anomalies occur: failures of formation, failures of segmentation, or a mixed deformity ( Fig. 72.1 ). Failures of formation and segmentation both may manifest as lateral-based structures, causing scoliosis; dorsal, causing lordosis; ventral, causing kyphosis; or a combination of these positions.

Subclassification of Congenital Vertebrae Anomalies.

Failures of formation include (A) wedge vertebrae–partial unilateral failure resulting in bilateral pedicles but asymmetric vertebral height and hemivertebrae of a complete unilateral failure with a single pedicle with variable growth potential, (B) segmented, (C) semisegmented, (D) incarcerated, and (E) nonsegmented. Failure of segmentation can manifest as (F) bar, a partial fusion between vertebrae, that prevents normal longitudinal growth on the fused side.

Failure of formation can be partial, which causes wedged vertebrae with intact pedicles, or complete, which causes hemivertebrae with a unilateral pedicle or occasionally complete absence of a vertebral segment. Subtypes of failure of formation abnormalities are named for their effect on the end plate, and therefore growth (see Fig. 72.1 ). Failure of segmentation during somatogenesis manifests as a spectrum. As with other bar malformations in the body, the bony vertebral bar resulting from a partial failure in segmentation will restrict growth in the same plane of direction as the bar. Vertebral anomalies often exist in conjunction as “mixed” deformity. Anomalies can be found on several levels. Multiple abnormal vertebrae may significantly complicate deformity or may functionally balance the curve. The natural history of congenital vertebral anomalies relates to the type of deformity, location, number and span of deformities, initial severity of curve, global growth potential, and balance of the spine.

Effects on Pulmonary Function ^,

Congenital abnormalities of vertebrae often occur with rib abnormalities. Rib fusion in the setting of an abnormal spine can lead to growth restriction of the thoracic cavity during a period of crucial pulmonary development. Alveolar development primarily occurs before 5 years of age, so ensuring that growth can occur as much as possible during this time is crucial. Should the growth abnormalities lead to enough restriction such that the tissue is unable to sufficiently develop, thoracic insufficiency syndrome (TIS) may develop. Early spine fusion before age 9, especially in patients requiring longer fusions, puts patients at risk for the development of restrictive pulmonary disease.

Associated Anomalies ^{, ,}

Because the development of the spine coincides with the development of many other organ systems, associated anomalies occur in 30% to 60% of children with congenital spine malformations. Many associated anomalies are part of the VACTERLS association. The acronym includes various deficiencies: vertebral defects (V), anal atresia (A), cardiac defects (C), tracheoesophageal fistula (TE), radial limb reduction and renal defects (R), limb defects (L), and single umbilical artery (S) ( Table 72.2 ). Additional testing other than those that serve to evaluate the spine are necessary. Collaboration with the patient’s primary care provider and other specialties will serve to prepare the surgical team and optimize the patient for surgery.

The most common anomalies involve the spinal cord, the genitourinary tract, and the cardiac system. Intraspinal anomalies include problems such as tethered cord, diastematomyelia, syringomyelia, Chiari malformations, and intradural lipomas. The most common genitourinary defects are horseshoe kidney, renal aplasia, ectopic kidney, duplication, reflux, and hypospadias. Congenital heart defects range from the more common atrial and ventricular septal defects to the more complex tetralogy of Fallot or transposition of the great vessels.

Caudal Regression Syndrome

Caudal regression syndrome, or sacral agenesis, manifests as the complete or partial absence of the sacrum and lower spine with corresponding distal absence or abnormalities of the nerves at that level. The pelvis and lower extremities are underdeveloped. Additional associated conditions include VACTERLS manifestations. Similar to spina bifida, motor deficits correspond to level of abnormality. However, in contrast to spina bifida, sensation distally is intact, which protects against pressure injuries and wounds. Caudal regression syndrome has been associated with maternal diabetes.

Skeletal Dysplasias

Skeletal dysplasias represent a diverse group of disorders characterized by disordered bone and/or cartilage growth. Several skeletal dysplasias are commonly accompanied by spinal problems, some of which can be appreciated in the neonatal period. Developmental and degenerative abnormalities can result in spinal cord compression and impingement on associated neural elements. Resulting neurologic complications, including pain and paralysis, significantly reduce patient quality of life and life expectancy.

Physical Exam

The physical examination of a patient with neonatal spine deformity is guided by the knowledge of a high frequency of other structural and neural anomalies. Maternal and perinatal history and developmental milestones must be fully explored. Presence of a dimple, nevi, hemangiomas or hairy patches, and/or any other cutaneous mark on the back should be noted. The sagittal plane balance and coronal balance, shoulder malalignment, and any deviation of the head and trunk from the center of the pelvis should be checked. The cervical spine should be especially examined, including range of neck motion. In addition, it is critical to assess and document the neurologic status, including strength, reflexes, the presence of atrophy, and the existence of latent ataxia or myelopathy. Flexibility of the deformity, trunk shortening, and limb-length inequality should be checked. Pain, if present, should be localized when able. The examiner should search for other anomalies of the extremities (particularly limb malformation).

Ultrasound ^,

Ultrasound in the prenatal and postdelivery perinatal period can be a useful tool in the early diagnosis of spine deformity. In addition to the other early screening methods, ultrasound offers a noninvasive, radiation-free, cost-effective, and reliable diagnosis for pathologies such as spina bifida and some skeletal dysplasias. The spine itself can be imaged in sagittal, axial, and coronal planes starting in the late first trimester ( Fig. 72.2 ). Additional musculoskeletal features including limb length and talipes can also been seen via ultrasound. Early diagnosis of spine pathology is advantageous to aid in family discussion and guidance, appropriately prepare the delivery team for prompt neonatal care, and potentially provide in utero therapy.

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