7.1 Patient Evaluation

A detailed clinical assessment of every patient with a congenital deformity of the spine is of prime importance to identify associated abnormalities affecting multiple organ systems; these can have major implications not only on spinal care but also on the overall well-being of the patient. The assessment should include a thorough physical examination, including repeated measurements of height, weight, arm span, and body mass index (BMI) at every clinical visit; these will indicate the progress of skeletal growth, which can have a direct effect on the deterioration of a spinal deformity. A low BMI correlates strongly with reduced pulmonary function and restrictive lung disease, indicating thoracic insufficiency syndrome. Patients with congenital vertebral anomalies need to be assessed for concurrent abnormalities of the ribs and thoracic cage with regular pulmonary function tests, including measurements of inspiratory and expiratory chest capacity, as well as lung volumes. Thoracic insufficiency is a dreaded complication that often occurs in patients with complex congenital vertebral defects in conjunction with spondylocostal or spondylothoracic dysplasia and Jarcho–Levin syndrome, and it can result in a major constriction of respiratory function and a short life expectancy.

7.2 Associated Skeletal and Systemic Anomalies

The vertebrae, neural structures, and musculoskeletal, cardiovascular, and genitourinary systems develop during similar stages of embryogenesis. As a consequence, embryonic insults affecting one or more of these systems simultaneously can be expected. The incidence of abnormalities affecting other organ systems in patients with congenital deformities of the spine, especially those due to mixed vertebral anomalies, can be greater than 61%. The patients in this group present with isolated defects involving one or more systems, or their clinical picture can be the expression of one of the following syndromic conditions: VATER (coexistence of vertebral, anorectal, trachea-esophageal, and renal anomalies); VACTERL (all of the above with the addition of cardiac and limb anomalies); Goldenhar (oculo-auriculo-vertebral) syndrome; Noonan syndrome (congenital cardiac disease, short stature, cervical fusions, Chiari I malformation, pectus carinatum or excavatum, low muscle tone); and Poland syndrome (ipsilateral hand and pectoralis major anomalies).

7.2.1 Musculoskeletal Anomalies

Spinal Column

The evaluation of a patient with a congenital deformity of the spine should include the entire length of the vertebral column because anomalies can concomitantly affect different areas and not necessarily produce a clinically obvious curvature. Klippel–Feil syndrome manifests with a short neck, low posterior hairline, and congenital fusion of two or more cervical vertebrae; this has to be excluded because it may result in limitation of neck movement and, over time, segmental instability at levels proximal or distal to the abnormality. Congenital cervical anomalies are particularly associated with a congenital scoliosis affecting the thoracic or lumbar spine. A common location for a unilateral unsegmented bar with or without a contralateral hemivertebra or mixed congenital vertebral defects is the area around the cervicothoracic junction, and these anomalies may be associated with Klippel–Feil syndrome. As a consequence, they can produce an elevation of the convex shoulder and head tilt toward the concavity of the scoliosis.

Other Skeletal Anomalies

Other skeletal abnormalities associated with a congenital deformity of the spine include craniofacial malformations, radial club hand, thumb hypoplasia, developmental hip dysplasia, club foot, cavus foot, vertical talus, and deficiencies or atrophies of the upper or lower limbs.

Congenital Elevated Scapula (Sprengel Shoulder)

Congenital elevated scapula occurs in patients with congenital spinal deformities at a prevalence of 7% and is mostly associated with a cervicothoracic or thoracic scoliosis due to a unilateral failure of vertebral segmentation. The combination of a congenital high scapula lying on the convexity of a congenital upper thoracic scoliosis creates a significant deformity due to elevation of the shoulder line and occasionally impairment of shoulder function. In such a situation, surgical treatment is often needed for both problems—to address the scoliosis and to reduce the scapula to its anatomically normal position in relation to the spine. However, when a Sprengel deformity is located on the concavity of a scoliosis, it often partly compensates for the cosmetic deformity produced by the elevation of the contralateral shoulder on the convexity of the curve. This minimizes shoulder asymmetry, and surgical treatment to restore the scapula to its normal location is usually not required.

Rib Anomalies

The ribs and chest wall form in close association with the vertebral column; abnormalities affecting thoracic cage development have been recorded in 19.2% of the patients with congenital deformities of the spine followed in our center. These developmental rib and chest wall anomalies may be simple (79%) or complex (21%) and are due to a failure of either segmentation or formation of the ribs (Fig. 7.1). The most common simple anomaly of the ribs is a localized fusion of two to three consecutive ribs; the most common complex abnormality is a combination of fused ribs with an adjacent large thoracic wall defect.

Congenital rib anomalies usually occur on the concavity of a thoracic or thoracolumbar congenital scoliosis caused by a unilateral failure of vertebral segmentation. A likely explanation for the close association between rib abnormalities and this type of congenital scoliosis is a localized embryologic error occurring during the initial developmental stage that results in a failure of segmentation of both the primitive ribs and vertebrae on the same side. The rib abnormalities do not appear to have an adverse effect on the degree or rate of progression of the deformity; these are determined primarily by the vertebral segmentation defect, which produces a severe unilateral imbalance in the longitudinal growth of the spine. The main driving force for the development of scoliosis in this group of patients is the unilateral failure of vertebral segmentation, the effect of which greatly exceeds any adverse effect due to rib fusions.

A long congenital thoracic scoliosis associated with fused ribs may affect thoracic function and growth of the lungs in young children and lead to thoracic insufficiency syndrome. This condition is usually due to a congenital failure of vertebral segmentation, which inhibits longitudinal growth of the spine and in turn vertical development of the thoracic cage. The coexistence of rib fusions will further restrict chest development on the concave side of the scoliosis and result in underdevelopment of the lungs and restrictive pulmonary disease. An imbalance in the mechanical thrust of the ribs may adversely affect spinal growth as well as the function of trunk muscles and thus increase pressure within the thorax. Rib and chest wall abnormalities have been observed less frequently in patients with congenital lumbar or lumbosacral scoliosis, congenital kyphoscoliosis, or pure kyphosis.

7.2.2 Intraspinal Abnormalities

Intraspinal anomalies can be associated with a scoliosis that is not due to congenital vertebral defects (scoliosis associated with spinal dysraphism). More commonly, spinal dysraphism may occur in conjunction with congenital vertebral anomalies that include Chiari or Dandy–Walker malformations, syringomyelia, tethering of the cord, diastematomyelia, dural bands or cysts, intradural lipomas, and tight filum terminale (Fig. 7.2). More than one dysraphic change can affect the same patient, and these are more prevalent in association with a congenital scoliosis due to mixed or vertebral segmentation abnormalities. The incidence of spinal dysraphism is 18 to 37%, with tethered cord most frequently encountered in patients with a congenital scoliosis.

Patients with congenital deformities of the spine and intraspinal anomalies may be completely asymptomatic; the absence of neurologic deficits or cutaneous lesions overlying the vertebral column does not rule out a dysraphic change. The presence of a cutaneous lesion such as a hairy patch, skin dimple or tag, vascular pigmentation, or hemangioma increases the possibility of an underlying dysraphic anomaly. Children with intraspinal pathology may present with neurologic signs and symptoms varying from subtly asymmetric leg tendon or abdominal reflexes to gait disturbance, severe motor and sensory deficits, bowel and bladder dysfunction, foot deformities, and lower limb muscle atrophy or contracture.

A detailed neurologic examination is mandatory to detect deficits. This should include an evaluation of motor and sensory function as well as the tendon reflexes in both upper and lower limbs; the examiner should assess for signs of nerve root tension and symmetry of the abdominal reflexes and should exclude the presence of clonus. Magnetic resonance (MR) imaging of the entire spine should be routinely performed when congenital vertebral anomalies are identified on plain radiographs, especially if surgical treatment is planned. MR imaging of the brain is indicated in a patient with a Chiari malformation, which can produce an increased fluid collection in the ventricles and raised intracranial pressure. Intraspinal abnormalities can occasionally affect the risk for and rate of deformity progression more than the associated congenital vertebral defects. The surgical correction of a spinal deformity can result in severe neurologic complications if it is undertaken before the dysraphic pathology is treated, particularly in the case of a fixed cord due to distal tethering, a diastematomyelia (typically a split cord due to a bony spur or fibrous band), or herniation of the cerebellar tonsils through the foramen magnum. The intraspinal anomaly is usually addressed first, with subsequent surgery to treat the progressive spinal deformity. Recent reports have indicated possible benefits of the simultaneous treatment of both types of pathology during the same procedure.

7.3 Imaging

Plain radiographs of the spine can facilitate recognition of the anatomical pattern and the classification of congenital vertebral anomalies, as well as the detection of curve progression and the response to treatment. The radiographs are taken with the patient standing except in the case of infants before walking stage; radiographs can be obtained while they are supine or sitting. As the patient’s development progresses from the supine to the sitting stage, apparent curve deterioration may be observed and does not necessarily signify true aggravation of the deformity. A lateral radiograph is necessary to exclude associated kyphosis, which carries the highest risk for neurologic complications.

Posteroanterior and lateral radiographs can be obtained to determine the type of vertebral abnormality, measure the size of the curvature, and assess growth potential around the area of the vertebral anomalies. Curve progression can be documented by using consistent anatomical landmarks on serial radiographs; errors in the Cobb angle measurement can vary between 3 and 12 degrees. Defining the growth potential of the vertebral abnormality provides an indication of the risk for curve deterioration until skeletal maturity. A fully segmented hemivertebra with normal disk spaces and end plates both above and below can be considered an example of maximal asymmetric growth and increased risk for scoliosis progression compared with a semisegmented or incarcerated hemivertebra, and this can usually be recognized on plain radiographs. The prognosis of a patient with a unilateral unsegmented bar to a large degree depends on whether open, normal-appearing disk spaces are present on the opposite side, indicating active growth plates and an increased deforming force. Radiographs, including supine traction and side-bending views as well as views obtained with the patient lying against a bolster, can also be used during surgical planning to assess the flexibility of the deformity in the coronal and sagittal planes.

The advent of computed tomography (CT) has improved the ability to determine in detail the spatial anatomy of vertebral abnormalities, including posterior element defects. The three-dimensional reconstruction of CT scans has become an integral part of surgical planning, with a reported 100% accuracy in recognizing anomalies that were discovered during surgery but were undetected on plain films. MR imaging of the spine has replaced myelography as the procedure of choice to detect occult spinal dysraphism, and all patients with a progressive deformity that requires surgical treatment should undergo this procedure, as should patients with abnormal neurologic findings and symptoms or coexisting cutaneous lesions over the spine. Spinal MR imaging will also demonstrate canal stenosis and cord compression in patients with a posterior or posterolateral hemivertebra and a kyphotic or kyphoscoliotic deformity, as well as the response to surgical treatment.