CHAPTER 119

Musculoskeletal Disorders of the Neck and Back

Aaron W. Beck, MD, MMS; Kier Maddox Blevins, MD; Andrew K. Battenberg, MD; and Carol D. Berkowitz, MD, FAAP

Children with disorders of the spine can present with deformity or back pain or occasionally, both. Atraumatic congenital and developmental deformities of the spine are frequently encountered in pediatric practice. Torticollis and scoliosis are 2 of the most common disorders in children that present as spinal deformity. Torticollis, or wry neck, is a positional abnormality of the neck resulting in abnormal tilting and rotation of the head. Scoliosis refers to any lateral curvature of the spine that measures more than 10° as determined on an anteroposterior radiograph of the spine. Scoliosis is classified as congenital, neuromuscular, or idiopathic. Idiopathic scoliosis itself is further categorized based on patient age: infantile, younger than 3 years; juvenile, 3 through 10 years; and adolescent, older than 10 years. Back pain is far less common in children than in adults. In children, such pain usually signals the presence of organic disease. In adolescents, however, back pain can result from musculoskeletal strain or from spondylolysis (ie, fracture of pars interarticularis).

Epidemiology

The most common type of torticollis in children is congenital muscular torticollis. The prevalence in the United States is estimated to be between 0.3% and 2% and is increased in breech presentations (eg, 1.8% breech presentation vs 0.3% vertex presentation). It occurs in up to 1 in 250 live births and is associated with developmental dysplasia of the hip (DDH) in up to 10% to 20% of affected infants. Family history may be positive in up to 10% of cases.

Acquired torticollis is much more common in older children and usually is secondary to trauma or infection, including cervical lymphadenitis, retropharyngeal abscess, myositis, and even upper respiratory tract infections. Episodes of benign paroxysmal torticollis, which often begin in the first year after birth and generally resolve by 5 years of age, may have a familial basis. An association with benign paroxysmal vertigo and migraines has been noted.

Some degree of spinal asymmetry or scoliosis occurs in approximately 2% to 5% of the population. Infantile scoliosis is rare in the United States and usually spontaneously resolves. The prevalence of juvenile scoliosis among school-age children in the United States is 3% to 5%. A right thoracic single curve is the most common curve seen by physicians. Seventy-five percent to 80% of cases of structural scoliosis are idiopathic, 10% are the result of neuromuscular causes, 5% are congenital, and the remaining 5% to 10% are the result of trauma or miscellaneous causes. Scoliosis that begins in childhood affects boys and girls equally, and affected boys outnumber girls from birth to age 3 years. Idiopathic scoliosis that manifests after age 10 years is more common in girls than boys, however, with a ratio estimated between 5:1 and 7:1. In children with cerebral palsy, the incidence of scoliosis is increased, occurring in approximately 20% of children with cerebral palsy.

Back pain is quite uncommon in preadolescent children. Unlike in adults, in whom it is often difficult to identify the cause, most instances of back pain in children have an identifiable etiology.

Clinical Presentation

Although torticollis may be noted at birth, it usually presents at 2 to 4 weeks of age. Infants with congenital muscular torticollis present with a characteristic head tilt toward the affected side with the chin pointing toward the opposite side; this positioning is secondary to unilateral fibrosis and contracture of the sternocleidomastoid muscle (Figure 119.1). Unrecognized or untreated torticollis may present as plagiocephaly (see Chapter 85) or facial asymmetry during infancy. Benign paroxysmal torticollis of infancy may present as recurrent episodes of head tilt that may be associated with vomiting, ataxia, agitation, or malaise (Box 119.1).

Mild scoliosis may not present with obvious deformity. Shoulder height asymmetry, scapular prominence or position, rib prominence or hump, waistline asymmetry or pelvic tilt, and leg length discrepancy may all be presenting signs of scoliosis (Box 119.1) (Figure 119.2A). Scoliosis may be detected during school-based screening programs or preparticipation sports physical examinations. Back pain is reported in 25% of adolescents with idiopathic scoliosis. When pain is present, further examination for some other cause (eg, bone tumors, spondylolysis, spondylolisthesis) is warranted. Preverbal children with back pain may present with limp or refusal to bear weight.

Pathophysiology

Torticollis may be either congenital or acquired. The etiology of congenital muscular torticollis is unknown. It is believed to be the result of intrauterine positioning or trauma to soft tissue of the neck during delivery, resulting in venous occlusion and ischemia of the sternocleidomastoid muscle. This causes edema and degeneration of the muscle fibers with eventual fibrosis of the muscle body. However, a prospective study of 821 patients with congenital muscular torticollis found that 55% of patients had a sternocleidomastoid tumor, 34% patients had thickening and tightness of the sternocleidomastoid, and 11% had head tilt without tumor or thickening of the sternocleidomastoid. Deformities of the face and skull may result if the condition is left untreated. Plagiocephaly (ie, cranial asymmetry), with flattening of the face on the affected side and flattening of the occiput on the contralateral side, is an associated finding.

Figure 119.1. Illustration of an infant with congenital muscular torticollis with the characteristic head tilt.

Figure 119.2. Illustration of a child with scoliosis. A, Rear view with the child standing. B, Rear view of the forward bend test.

Unlike kyphosis and lordosis, which are curves in the anteriorposterior plane, scoliosis is a lateral curvature of the spine occurring in the coronal plane. Scoliosis can be either functional (ie, nonstructural) or structural. In functional scoliosis, there is no fixed deformity of the spine and the apparent curvature disappears on lying down or on forward flexion. Individuals with leg length discrepancies may appear to have scoliosis but have no spinal abnormality. Structural scoliosis may be idiopathic or caused by various underlying disorders, such as muscular dystrophy or cerebral palsy in the nonidiopathic neuromuscular forms. The cause of idiopathic scoliosis is unknown, but there appears to be a higher incidence of scoliosis amongst other family members. Abnormalities of fibrillin have also been noted in some patients with scoliosis, a finding that is reported in patients with Marfan syndrome as well. In structural scoliosis, the spine has both a coronal curvature and a rotational component, which results in deformity of attached structures. For example, a “rib hump” may be produced as a result of scoliosis in the thoracic spine (Figure 119.2B). Pelvic obliquity or flank prominence may be produced when the curvature is in the lumbar spine.

Differential Diagnosis

The differential diagnosis of congenital and acquired torticollis is presented in Box 119.2. Torticollis not at birth is termed congenital muscular torticollis and is differentiated from acquired torticollis, which occurs in older infants and children and is secondary to another condition. When torticollis occurs in association with nystagmus and head nodding, this clinical triad is referred to as “spasmus nutans.” Cervical lymphadenitis is a common cause of acquired torticollis that is seen in children 1 to 5 years of age, whereas trauma to the soft tissues or muscles of the neck is seen more frequently in school-age children. Acute episodes (eg, benign paroxysmal torticollis of infancy) must be differentiated from chronic conditions (eg, Sandifer syndrome, rheumatoid arthritis) based on the history.

Functional or nonstructural scoliosis may occur secondary to poor posture, leg length discrepancy, or muscle spasm. Structural scoliosis can be classified as idiopathic, congenital, neuromuscular, or miscellaneous (Box 119.3). Idiopathic scoliosis, which is by far the most common type of structural scoliosis, may be divided into 3 categories based on age: infantile (<3 years), juvenile (3–10 years), and adolescent (>10 years). The adolescent form occurs most frequently, accounting for up to 85% of cases.

Congenital scoliosis arises from anomalies in the development of the spine resulting in hemivertebrae or unsegmented vertebral bars. Because of the high incidence of anomalies in other body systems, such as cardiac and genitourinary anomalies, patients with congenital scoliosis require screening for associated abnormalities. Although neuromuscular scoliosis is most often seen in children with spastic cerebral palsy, it may be apparent in other conditions as well, such as poliomyelitis, meningomyelocele, muscular dystrophy, Friedreich ataxia, and spinal muscular atrophy. The miscellaneous causes of scoliosis are uncommon and include trauma, metabolic disorders, and neurocutaneous diseases.

The most common causes of back pain in children may be classified into 5 distinct categories (Box 119.4). When pain is significant enough that a child presents to the emergency department, common causes include trauma (25%), muscle strain (24%), sickle cell crisis (13%), idiopathic cause (13%), urinary tract infection (5%), viral syndrome (4%), and not categorized (16%). Other infectious causes, such as diskitis, occur much more frequently in children than adults. However, diskitis is rare in the pediatric population, with an estimated 1 to 2 cases per 32,500 pediatric emergency encounters. A child presenting with back pain should also be considered for an oncologic process, such as osteoid osteoma, osteoblastoma, or hemangioma. Because the spine of children is smaller and has greater flexibility and ligamentous strength than the adult spine, children are at lower risk of traumatic injury than adults. Common causes of back pain in adults, such as musculoskeletal back pain (ie, muscle strain) and discogenic pain, are uncommon in children. Individuals who are predisposed to musculoskeletal back pain often experience their first episode during adolescence or young adulthood; only 1% to 4% of disk herniations occur in children.

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