Back Pain in Children and Adolescents

8
Back Pain in Children and Adolescents

Katherine M. Schroeder, Erica E. Gonzalez, and John P. Dormans

■ Introduction

Historically, back pain in children and adolescents was considered rare and often a serious complaint. However, its prevalence has increased over recent years.^1,2 Although the cause of back pain is often associated with a condition that improves spontaneously and has a favorable natural history, providers should have a high index of suspicion for more serious pathologies. This chapter reviews the epidemiology, evaluation, differential diagnosis, and initial treatment of children and adolescents who present with complaints of back pain.

■ Epidemiology

Back pain in the pediatric population is more common than previously thought,^1,2 with reported rates of 7 to 58% in the literature.³ It can be expected that 10 to 30% of the normal pediatric population will experience back pain at some point by the time they reach adolescence.⁴ Reported risk factors for childhood back pain include older age, a family history of back pain, increased physical activity or participation in competitive sports, manual work, and carrying a heavy backpack.³

■ Clinical Evaluation

A detailed history and physical examination are essential when evaluating a child or adolescent with back pain. Duration, severity, frequency and inciting factors should be determined. Any history of trauma, recent illness, or infection should be documented. Potential warning signs should be further investigated, including constitutional symptoms such as night sweats or weight loss, severe pain, recurrent or worsening back pain, night pain, limp or altered gait, and back pain in a younger child, especially under the age of 5 years (Table 8.1 ).² A full physical exam should be performed, including inspecting the child’s spine for midline lesions that may indicate intraspinal pathology. The spine should be palpated for tenderness, masses, or stepoff of the posterior elements. Range of motion of the spine, significant kyphosis or lordosis, and gait should be assessed, and the Adams forward bend test should be performed. A complete neurologic examination should be performed, including motor and sensory exams, as well as deep tendon reflexes, abdominal reflexes, and upper motor neuron signs.¹ In 2010, Fujimori et al⁵ reported that the sensitivity of the abnormal superficial abdominal reflex for syringomyelia in presumed idiopathic scoliosis was 89%, with a 95% specificity.

Table 8.1 “Red Flags” in the Initial Assessment of a Pediatric Patient Presenting with Back Pain

“Red Flags” from the History	“Red Flags” on the Physical Examination
Severe, worsening, or recurring pain	Neurologic symptoms
Night pain	Limp/gait abnormality
Fever, weight loss, reduced appetite	Fever, tachycardia
Loss of bowel/bladder control	Progressive deformity
Refusal to bear weight	Abnormal bruising or bleeding
Back pain in a young child (< 5 years of age)	Lymphadenopathy or abdominal mass
Lost or delayed developmental milestones

A cavus foot can also be a sign of intraspinal pathology. It is also often useful to do a thorough hip exam, assess pelvic obliquity, and look for a leg length discrepancy that may be associated with the patient’s complaint of back pain. A wide differential diagnosis should be kept in mind during the initial evaluation (Box 8.1). A high index of suspicion should be maintained when evaluating a child with back pain, as pain is the most common presenting complaint for most tumors and infections in the pediatric spine and pelvis.

Box 8.1 Differential Diagnosis of Back Pain in a Child or Adolescent

♦ Nonspecific/mechanical low back pain

♦ Spondylolysis and spondylolisthesis

♦ Scheuermann kyphosis

♦ Scoliosis

♦ Lumbar disk herniation

♦ Trauma

♦ Infection: diskitis, vertebral osteomyelitis, sacroiliac joint infection, epidural abscess

♦ Benign neoplasms: Langerhans cell histiocytosis, aneurysmal bone cyst, osteoblastoma, osteoid osteoma, osteochondroma

♦ Malignant neoplasms: Ewing sarcoma, osteogenic sarcoma, chondrosarcoma, leukemia

♦ Metastatic disease: rhabdomyosarcoma, neuroblastoma, Wilms’ tumor, lymphoma

♦ Intraspinal tumor: astrocytoma, ependymoma

♦ Systemic causes: osteoporosis, juvenile idiopathic arthritis

♦ Referred back pain: renal abnormalities, pyelonephritis, retroperitoneal lesions, pelvic inflammatory disease

Full length posteroanterior (PA) and lateral spine radiographs should be obtained in most cases. Further imaging studies should be utilized as indicated. Magnetic resonance imaging (MRI), computed tomography (CT), and bone scans all have a role in spine imaging. MRI is considered the gold standard for most spinal pathologies, particularly the more serious pathologies such as tumors or infection. It should be kept in mind that younger patients require sedation for an MRI, and this may require that the study be done at a children’s hospital or at a facility with appropriate anesthesia support. Single photon emission computed tomography (SPECT) and CT scans are primarily used in the diagnosis of spondylolysis, but they can also be used in the acute trauma situation when a fracture may be suspected. The use of bone scans has decreased over recent years, but they are still used to diagnose a stress reaction in the par interarticularis. A bone scan may also be useful if the patient has multiple sites of complaints or if there is concern about a multifocal process such as leukemia, Langerhans cell histiocytosis (LCH), chronic recurrent multifocal osteomyelitis (CRMO), or metastasis. It is important to review the patient’s previous imaging rather than relying on just the imaging report, as adult radiologists may be less familiar with pediatric spine conditions.

Laboratory studies are useful, particularly where there is suspicion for infection or tumor. A complete blood count with peripheral blood smear can be useful in the diagnosis of leukemia. Although nonspecific, increases in the white blood cell count and an elevated C-reactive protein and erythrocyte sedimentation rate can be seen in most patients with an infection, but may also be seen in patients with malignancies.6 Blood cultures can be useful in identifying an organism in patients with diskitis or vertebral osteomyelitis.⁶

It is important to remember that back pain can be a referred pain, a symptom, for example, of renal, urinary, abdominal, or gynecologic problems. Lymphoma and leukemia can also present with back pain. If the picture is unclear or if one of these pathologies is suspected, it is important to involve the patient’s primary care physician or other specialists.

■ Nonspecific Low Back Pain

Nonspecific back pain can be defined as pain when there is no identifiable etiology. Sources of nonspecific low back pain can be muscle strain, overuse, contusion, poor posture, or deconditioning. Running, lifting weight, or frequent sitting typically brings on the pain. It was originally thought that the majority of children and adolescents who present with back pain had diagnosable pathologies, but recent reports have found that mechanical or nonspecific back pain can be seen in up to 75% of adolescents presenting with back pain.^7,8 This is generally a diagnosis of exclusion after a thorough history and physical. The first line of treatment is physical therapy and activity modification, particularly if an overuse injury is suspected.

Even a patient with negative initial imaging and suspected nonspecific back pain should be followed to ensure that the pain is improving. Worsening pain or symptoms could suggest another diagnosis, and thus further workup is indicated.

■ Spondylolysis and Spondylolisthesis

Spondylolysis and spondylolisthesis are common causes of back pain in children over the age of 10 years and are rarely seen in children under the age of 5 years.^3,9 Spondylolysis is a defect in the pars interarticularis and most commonly affects the fifth lumbar vertebra. The isthmic type of spondylolysis is caused by a stress fracture of the pars interarticularis and is thought to result from repetitive microtrauma to the segment. Spondylolisthesis occurs in the presence of bilateral pars defects, when one vertebra translates anteriorly on the more caudal vertebra. This can cause compression of exiting nerve roots and, in some cases, subsequent neurodeficits. In children and adolescents, spondylolisthesis is most commonly seen at the L5-S1 segment.² The dysplastic pars defect occurs secondarily to elongation of the pars. It is thought to be a consequence of a congenital defect and is a less common source of spondylolisthesis.¹

Spondylolysis is traditionally seen in boys who participate in sports with repetitive extension, flexion, or rotation of the lumbar spine.^1,3,8 Typical symptoms include low back pain, pain with lumbar extension, and occasionally radiating pain to the buttock or posterior thigh. In general, the patient reports a history of insidious onset of low back pain, rather than an acute injury. On exam, the patient may have tenderness over the lumbar spinous processes or paraspinal muscles and often has pain with extension of the lumbar spine.

Initial imaging should include PA and lateral radiographs of the lumbar spine. Oblique radiographs, although often used, have not been shown to increase the diagnostic accuracy beyond standard PA and lateral views, particularly for spondylolysis.^7,10 SPECT, bone scan, and MRI have all been used for the diagnosis of spondylolysis. Miller et al⁷ reported that CT and plain films had higher sensitivity for diagnosis of spondylolysis compared with bone scan with lower radiation (Fig. 8.1). Recently, MRI has also been shown to have comparable sensitivity to CT scan in the diagnosis of spondylolysis.¹¹ It may also be advantageous in diagnosing an early stress reaction in the pars that may otherwise not be seen on CT scan. MRI has the additional advantages of detecting soft tissue pathology and entailing no radiation. Spondylolisthesis is best diagnosed on a standing lateral radiograph. Standing radiographs are essential in determining the degree of the listhesis, as it may reduce with supine positioning.

Fig. 8.1 (a) Axial and (b) sagittal computed tomography (CT) scans demonstrate spondylolysis with bilateral L5 pars defects.

Nonsurgical management of spondylolysis includes bracing, activity modification, physical therapy, and nonsteroidal anti-inflammatory drugs (NSAIDs). A 2009 meta-analysis of spondylolysis and grade I spondylolisthesis found an 83.9% success rate of nonoperative treatment after 1 year.12 In this study, neither bracing nor healing of the lesion correlated with successful treatment outcomes. It is generally accepted that healing of the lesion does not correlate with successful outcomes in patients with spondylolysis, and this should be discussed with the patient and family during the initial discussion of treatment goals. In patients with spondylolysis or low-grade spondylolisthesis, surgical treatment is generally reserved for patients who have continued symptoms after more than 6 months of nonoperative treatment.

■ Scheuermann Kyphosis

Scheuermann kyphosis can be a source of pain in older adolescents. It is a structural kyphotic deformity in the thoracic or thoracolumbar spine and can be distinguished from postural kyphosis by the inability to correct the kyphosis with extension. Patients often also present with compensatory lumbar and cervical lordosis, and sometimes complain of pain at the apex of the thoracic kyphosis or at the hyperlordotic lumbar area. A lateral radiograph of the spine demonstrates > 5 degrees of anterior wedging of at least three adjacent vertebra and > 45 degrees of regional kyphosis.¹ Schmorl nodes, end-plate irregularities, and narrowing of the disk spaces are also seen. PA and lateral radiographs should be obtained to measure the degree of kyphosis and to rule out other pathology, such as spondylolysis or spondylolisthesis.

Nonoperative treatment with bracing can be used in the growing child, and the braces should be tailored to the apex of the kyphosis. If the apex of the Scheuermann deformity is cranial to T7, a Milwaukee brace is recommended. Lower thoracic or thoracolumbar deformities can be managed with an underarm brace.1 Physical therapy focusing on posture, trunk strengthening, and hamstring stretching can also be useful. Surgical treatment for Scheuermann kyphosis is generally reserved for those patients who have continued progression of the kyphosis despite skeletal maturity or continued pain despite nonsurgical treatment with physical therapy.

■ Adolescent Idiopathic Scoliosis

Patients with idiopathic scoliosis often present with shoulder asymmetry or rib prominence and may be referred by the pediatrician or school nurse. Occasionally, patients with scoliosis may present with back pain. A retrospective study of 2,442 patients with presumed idiopathic scoliosis found that 23% of the patients had back pain on presentation and another 9% developed back pain during the observation period¹³; 9% of the children with back pain and scoliosis had an underlying condition, most commonly spondylolysis or spondylolisthesis. Other diagnoses included Scheuermann kyphosis, syrinx, disk herniation, tethered cord, and intraspinal tumor.

As with all patients who present with scoliosis, a full neurologic exam should be performed and a thorough history should be taken. Standard PA and lateral radiographs of the spine should be obtained. An atypical scoliotic curve (i.e., left thoracic), rapidly progressing curve, or abnormal neurologic finding should prompt an MRI examination to further investigate another underlying condition.

■ Trauma

Lumbar disk herniation is less common in pediatric patients than in adults²; 30 to 60% of children and adolescents with symptomatic lumbar disk herniations have a history of trauma prior to the onset of pain.^1,14 Symptoms in pediatric patients tend to be similar to those seen in adults, with disk herniation, and radicular symptoms or pain with lumbar flexion. In one study, pediatric patients tended to have a greater nerve-root tension and 90% have a positive straight leg raise on exam.¹⁴ Saddle paresthesia or bowel or bladder dysfunction should raise concern about cauda equina syndrome. Plain radiographs should be ordered, but an MRI of the lumbar spine is the imaging modality of choice for disk herniation. In a 2008 study, adolescent disk herniation was associated with separation of the apophyseal ring in 28% of patients.¹⁵ CT scan may be used to confirm the apophyseal ring separation on axial imaging (Fig. 8.2).

Although the nonoperative success rate in pediatric patients is lower than that in adults,¹ most pediatric patients with lumbar disk herniation should be initially treated without surgery. Bed rest, activity restriction, anti-inflammatories, and physical therapy should be used initially. Indications for surgical management include failure of nonoperative treatment, progressive neurologic deficits, and cauda equina syndrome. Patients with apophyseal ring fragments have a higher rate of requiring surgery than those with disk herniations alone.¹⁵ Management of apophyseal ring fractures is similar to that for disk herniation. It has been suggested that the apophyseal ring fragment should be removed along with the disk, particularly in patients with neurologic deficits.¹