Persistant back pain in children necessitates a thorough evaluation to rule out disorders that can result in significant morbidity, such as infection or tumor. Back pain in younger children is unusual and suggests significant diseases. The prevalence of complaints of low back pain increases with age, and is as prevalent as 30% by the teenage years. Back pain is frequently mild and often resolves spontaneously in adolescents. The complaints are often related to overactivity in sports, work, or a specific traumatic event. Back pain is not a disease but a symptom and is often associated in adolescents with headaches, emotional problems, daytime tiredness, and behavioral disorders. Activity modification and rehabilitation or exercises for the spine are sufficient to prevent recurrent episodes of back pain. Severe or persistent back pain necessitates a thorough history, physical examination, and appropriate imaging studies to evaluate the child for potentially serious pathologic processes.
(See Nelson Textbook of Pediatrics, p. 3245.)
Evaluation of the Pediatric Spine
Examination of the spine should be part of the routine physical examination in the healthy child and adolescent. Even in patients who present with back pain as a chief complaint, the most important diagnostic steps are a detailed history and a thorough and systematic examination ( Table 35.1 ).
| History |
|
| Physical Examination |
| General Appearance |
|
| Motion |
|
| Lower Extremities |
|
When findings on screening examinations are abnormal or when a patient presents with complaints of back pain, a more detailed examination is required. The spinal vertebral column, spinal cord, and spinal nerves are intimately related, and disorders affecting any 1 of these elements produce symptoms and signs in the others. Detailed examination of strength in the muscles of the spine and lower extremities ( Fig. 35.1 ), sensation ( Fig. 35.2 ), abdominal and lower extremity reflexes, anal sphincter tone, and perianal sensation should be performed when the primary examination suggests involvement of the neural structures that pass through the spinal column. Persistent or severe back pain is uncommon in young children and may be associated with serious underlying disease.
Normal Growth and Development of the Spine
Vertebral growth occurs in an orderly manner throughout childhood and adolescence. About 50% of vertebral column height is present by the age of 2 years. Acceleration of vertebral growth occurs during the adolescent growth spurt but contributes less to total height than does lower limb growth; the sitting heights of siblings in early and late adolescence are often remarkably similar. Spinal growth slows at menarche in girls and at the time of voice change in boys and is usually complete 2-3 years later. Developmental abnormalities of the column, such as idiopathic scoliosis, most commonly first appear just before the growth spurt. Alterations in spinal configuration caused by congenital deformities of vertebral segments change most rapidly during periods of rapid spinal growth: before the age of 2 and at the time of the adolescent growth spurt.
There is a strong association of genitourinary tract, cardiac, and neural abnormalities in patients with congenital abnormalities of the spine. Warning signs in patients with congenital spine deformities include leg length inequality, foot size asymmetry, high foot arches, hairy patches or hemangiomas or a mass over the spine, sacral dimpling, enuresis, toe-walking, asymmetry or abnormality in the lower extremity deep tendon reflexes, and lower extremity weakness.
Normal Spinal Alignment
The normal trunk is symmetric when viewed from the front or the back ( Fig. 35.3 ). The shoulders and pelvis are parallel to each other and to the ground. The distance between the right and left elbows and the sides of the trunk is equal. When the trunk is viewed from the side, a series of curves is present (see Fig. 35.3 ). A convex anterior lordotic curve is present in the cervical region. The spine is concave anteriorly in a kyphotic pattern in the thoracic region. The normal lumbar spine is lordotic, and the sacrum and coccygeal regions are kyphotic. Normal adult sagittal alignment develops gradually; children younger than 10 years typically have less cervical lordosis and more lumbar lordosis than adults. Healthy children are often quite swaybacked. Injuries, infections, tumors, inflammation, and developmental abnormalities of the spine often produce alterations in these expected contours. Range of motion is demonstrated in Fig. 35.4 .
Back Pain of Brief Duration
Few children younger than 10 years sustain significant injuries of the spinal column or associated musculature in routine play and organized sports activities; extremity injuries are far more common. When the trunk is involved, contusions and abrasions are much more common than ligament sprains and muscle strains.
When a child presents with back pain of brief duration after a play- or sports-related injury, a careful examination should be performed. If there are no other associated injuries and the screening examination shows no alterations in trunk configuration or lower extremity strength or sensation (see Figs. 35.1 and 35.2 ), no further work-up is necessary. A brief period of rest for 1-2 days, followed by gradual resumption of activities, is appropriate treatment. Routine imaging is not necessary when the duration of symptoms is short and the physical examination findings are normal. Signs of systemic illness (fever, weight loss) or neurologic deficits warrant an immediate evaluation.
Acute back injuries occur more frequently in adolescence, as the sizes of participants and potential forces generated in recreational activities increase. If there are no other associated injuries and the screening examination findings are normal, no further imaging work-up is necessary. A period of rest followed by gradual resumption of activities is appropriate treatment. The importance of a comprehensive and balanced conditioning exercise program should be stressed to young athletes. Most sports-related injuries can be prevented by preparticipation conditioning, appropriate warm-up, careful supervision, and resting when fatigued.
Trauma sufficient to cause spine fractures may occur as a result of motor vehicle or bicycle crashes, falls, and diving and gymnastic injuries. The frequency and severity of spine trauma rises in later adolescence as exposure to potentially violent forces in sports and motor vehicles increases. In such cases, there is a clear relationship between the crash and the onset of symptoms. Injury to the spinal column should be suspected in all individuals whose level of consciousness is impaired after an accident, regardless of the presence or absence of symptoms.
Children with suspected acute spinal injury should be immobilized on backboards designed for children until definitive imaging studies can be performed and interpreted. Immobilization of the child’s cervical spine on a solid backboard should be avoided. The child’s occiput projects farther posteriorly than that of the adult, and flexion of the neck occurs if the child’s neck is immobilized on a standard backboard. Spinal immobilization boards for children are readily available and have a cut-out section to accommodate the occiput. When such boards are not available, a blanket or firm mattress should be interposed between the trunk and the backboard to prevent neck flexion.
Persistent Back Pain
Persistent or severe back pain is uncommon in young children but is more common in adolescents. Mechanical low back pain is said to be present in the patient with no definable pathology on physical exam or imaging studies. This is the case in over 50% of patients presenting with low back pain. The implications of severe or persistent back pain are more serious in younger patients than in adolescents. Persistent back pain in young children is usually not the result of a congenital spinal deformity or developmental disorders of the spine. As a child enters and passes through the adolescent growth spurt, back pain may arise from a small number of congenital and developmental disorders of the spinal column. Degenerative disorders of the spine such as intervertebral disk herniation are uncommon causes of back pain in childhood. In evaluating a patient, it is important to try to distinguish musculoskeletal-mechanical disorders from those with more generalized systemic signs or those suggestive of a neoplasia ( Fig. 35.5 ). If the MRI shows no definitive pathology, patients are considered to have mechanical low back pain and have continued conservative treatment. Pediatric multidisciplinary pain clinics also help those who have persistent pain, have no defined pathology, and have failed conservative treatment.
The differential diagnosis of persistent back pain in children younger than 10 years includes intervertebral diskitis and vertebral body osteomyelitis, neoplasia of the vertebrae, primary neoplasia of the spinal cord, and metastatic neoplasia ( Table 35.2 ). In older children and adolescents, congenital variations in the formation of the lower lumbar spine are sometimes responsible for chronic back pain (see Table 35.1 ). Developmental round back (kyphosis) is occasionally associated with midthoracic back pain in middle and late adolescence. Diskitis, skeletal neoplasia, and tumors of the spinal cord and nerves also occur in adolescence. In documenting the history, special attention must be given to the nature of the onset of symptoms, the presence of radiating pain in the legs, bowel and bladder function, associated abdominal pain, and the presence or absence of fever.
| Inflammatory Diseases |
| Rheumatologic Diseases |
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| Developmental Diseases |
| Mechanical Trauma and Abnormalities |
|
| Neoplastic Diseases |
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| Other |
|
Although this issue is controversial, some authorities believe that school-aged children who carry an excessively heavy backpack are at risk for back pain and alterations of gait or posture. To alleviate this, it is recommended that the backpack be of appropriate size with wide padded straps and back padding. In addition, the weight limit of the pack should not exceed 10-15% of the child’s body weight. The pack should be lifted with bending of the knees, and the straps should be adjusted so that the pack fits on the back and not below the waist.
Specific Diagnosis
Intervertebral Diskitis
Intervertebral diskitis is the term applied to a number of processes that are characterized by back or leg pain and identified radiographically by narrowing of the intervertebral joint space between 2 adjacent vertebral segments ( Figs. 35.6 and 35.7 ). Magnetic resonance imaging (MRI) studies suggest that diskitis may begin as a micro abscess within the vertebral body adjacent to the vertebral end plate. The disk becomes infected from perforating vascular channels across the end plate. Vascular channels may also perforate the end plate on the opposite side of the disk, leading to involvement of the opposite vertebral body. In some patients, the symptoms resolve spontaneously without treatment.
Most authorities believe that diskitis is a bacterial infection, usually caused by Staphylococcus aureus . Tuberculosis infection of the spine must also be considered in patients who have spent significant time outside the United States or in high-risk patients such as those who are immunocompromised. Surgical drainage, a critical component of effective treatment of other closed space infections of the musculoskeletal system, is not usually required in most patients with intervertebral diskitis.
Clinical Findings
Three age-dependent patterns of presentation have been noted for intervertebral diskitis. Children younger than 3 years (the most common age) often present with irritability and refusal to walk and sit or have apparent dysfunction (limp, antalgic gait) of the lower extremities. Patients may have very tight hamstrings, loss of lumbar lordosis (the lumbar spine is the most common site), and refusal to allow passive motion of the lumbar spine. Patients between the ages of 3 and 8 years often have pain referred to the abdomen, particularly when the disk involves the lower thoracic spine. Adolescents with diskitis often have back pain; the discomfort often radiates into both legs. Additional features at all ages include low-grade fever; refusal to bear weight (sitting or standing); hyperlordosis; and, if intraspinal inflammation is present, decreased lower extremity muscle strength, decreased tone, and alterations of deep tendon reflexes. The erythrocyte sedimentation rate is usually elevated; the white blood cell count is usually normal but may be elevated in late cases. Early in the process, plain radiographs of the spine are often normal. Over a certain period of time, the disk space narrowing develops with subsequent erosion of the vertebral end plates (see Fig. 35.6 ). Traditionally, a bone scan has been recommended for assessment of diskitis. However, MRI is more sensitive than the bone scan. The MRI reveals the extent of the inflammatory process better and can delineate the degree of bone destruction (if any), the presence of abscess formation, or intraspinal inflammation (see Fig. 35.7 ).
Treatment
The diagnosis of intervertebral diskitis should be suspected in young children with fever and unexplained back or leg pain and in previously healthy toddlers who become irritable and refuse to walk. Vertebral body osteomyelitis is a major consideration in the differential diagnosis and can usually be diagnosed with radiographs and MRI. After appropriate laboratory studies, including blood cultures, have been performed, treatment should be started. A bacterial cause is likely if fever, leukocytosis, and elevation of the sedimentation rate are present. Antibiotic therapy should be started in such cases, because S. aureus is the most commonly responsible organism. Knowing the antibacterial sensitivity patterns of community-acquired S. aureus helps the clinician choose the appropriate antibiotic (clindamycin, vancomycin, or methicillin). In immunocompromised hosts, broader spectrum antibiotic coverage is essential. If an organism is recovered, antibiotic coverage can be adjusted appropriately. Initial therapy should be intravenous; oral antibiotics can be considered as pain decreases and laboratory studies return to normal. A total of 4-6 weeks of therapy is recommended for patients with infectious intervertebral diskitis.
Immobilization of the spine is used for persistent symptoms. Patients without systemic signs of infection and in whom laboratory studies show no leukocytosis and only moderate elevation of the sedimentation rate may be occasionally managed by antiinflammatory agents and rest.
Patients who remain ill or worsen after the initiation of rest and antibiotic treatment should undergo surgical biopsy and drainage. Biopsy should also be performed in patients in whom tuberculous intervertebral disk space infection is suspected (positive exposure history, positive purified protein derivative findings; see Chapter 2 ).
The evolution of plain radiographic findings lags behind clinical findings in intervertebral diskitis. Although patients with intervertebral diskitis may experience disk space narrowing and end plate erosion during the course of treatment, normal radiographs and bone scans at the time of initial evaluation do not preclude the diagnosis. Radiographic changes continue long after the inflammatory process has resolved. Progressive disk space narrowing, intervertebral disk space calcification, and spontaneous intervertebral arthrodesis are potential late findings.
Lack of focal changes on plain films obtained 2-3 weeks after the onset of symptoms significantly lessens the likelihood of intervertebral diskitis. In such patients, careful study for other potential diagnoses is essential. Tumors of the spinal cord may manifest in a similar manner without causing the changes in the vertebral segments necessary to produce alterations on bone scanning. In such patients, MRI is invaluable.
Spondylolysis and Spondylolisthesis
(See Nelson Textbook of Pediatrics, p. 3293.)
The most common abnormalities of the lower lumbar and lumbosacral spine—spina bifida occulta, at L5 or S1, and spondylolysis, usually at L5 to S1—are often noted as incidental radiologic findings in entirely asymptomatic individuals. A few individuals with spondylolysis (defect in the pars interarticularis without slippage) experience back pain and progressive slippage deformity, known as spondylolisthesis.
As a consequence of the normal lordotic tilt of the lumbar spine, shear forces are generated between the L5 and S1 vertebral segments. Forward displacement of L5 on S1 is normally prevented by the stable articulation of the superior facets of S1 and the inferior facets of L5. Defective formation of the posterior elements of the lumbosacral joint or defects in the bone connection between the body and the arch of the 5th lumbar vertebra render the anterior junction of L5 and S1 unstable and may lead to relative displacement.
Cause
Spondylolysis and spondylolisthesis in children and adolescents usually involve the 5th lumbar and 1st sacral units. Spondylolysis is not present at birth, but with growth and activity, it is seen by age 6 years in about 4% of children and 6% of adults. Spondylolysis appears to be less common in black persons and much more common in some North American Eskimo groups; the lowest incidence has been reported in black females, and the highest in white males. The male to female ratio is 2 : 1. The disorder appears to be multifactorial; both hereditary and mechanical factors have been implicated. Relatives of patients with spondylolysis are much more likely to be affected than are individuals in the general population, although the degree of slippage is not as well correlated.
Fatigue fracture of the posterior elements of L5 may be responsible for acutely painful spondylolysis in some preadolescent and adolescent athletes ( Figs. 35.8, 35.9, and 35.10 ). Activities that involve repeated trunk flexion and extension have been implicated; adolescent divers and gymnasts are reported to be susceptible to spondylolysis and spondylolisthesis. A high rate of spondylolysis has been reported in Scheuermann disease (thoracic kyphosis), which may be related to compensatory excessive lumbar lordosis. In addition, an increased incidence of spondylolisthesis has been noted among both patients with myelodysplasia and those with cerebral palsy.
