Diagnosis and Management of Back Pain in Children
Diagnosis and Management of Back Pain in Children
Author: David Goff, MD, FAAP, Pediatrics and Internal Medicine, Clinical Assistant Professor of Pediatrics, Children's Hospital of Eastern North Carolina, Brody School of Medicine, East Carolina University.
Peer reviewer: Moira Davenport, MD, Department of Emergency Medicine, Department of Orthopaedic Surgery, Allegheny General Hospital, Pittsburgh, PA.
The incidence of back pain in children is directly proportional to the age of the child, with back pain an unusual complaint in children younger than age 6. There is a steady increase in incidence, with adolescents having the highest rates of back pain by the time they are age 18. Approximately 60% of adults experience significant back pain in their lifetimes.
The duration of back pain is a paramount factor in the consideration of the etiology of children's back pain. The overwhelming majority of children have short-duration back pain of less than one week, with good outcomes. It is back pain of more than four weeks, or back pain with red flags such as neurological findings or fever, that require more immediate evaluation.
Back pain persisting for more than four weeks will have a specific etiology in more than 50% of the patients evaluated. It is important for the clinician to thoroughly understand the differential diagnosis and prevalence of back pain in children to determine appropriate patient care.
The Editor
Introduction
Back pain is uncommon in children younger than age 6. The incidence steadily increases during the teenage years and approaches 60% in adults. Its prevalence is about 1% at age 6 and rises to 10% by late adolescence. In the pediatric literature, Turner and colleagues found a specific etiology in approximately one-half of children younger than age 15 who were referred to a children's orthopedic clinic in England with pain persisting for more than four weeks.1 The recent literature on back pain in children2-5 validates that approximately 50% of cases of back pain lasting for more than one month will have a specific cause, and that the appropriate use of plain radiography, bone scans, CT scans, and magnetic resonance imaging (MRI) modalities will lead to the specific diagnosis. However, it is important to point out that back pain usually is short lived in children. Jones and colleagues found that 18% of 1046 children ages 11 to 14 in secondary schools in New England had back pain for more than one day in the month previous to the study, and the average duration of back pain was three days (with a range of two to seven days).6 Therefore, because it is self limited and lasts only a few days, we as clinicians will not see the vast majority of children with acute back pain.
In the study by Turner and coworkers, the authors noted that the 61 patients who were referred to the children's orthopedic clinic for back pain accounted for 2% of non-trauma referrals, with more than 90% being 12 to 15 years old.1 The study by de Inocencio found that only 6% (60 of 1000 visits) of primary care visits to an urban general pediatric clinic in Madrid, Spain, concerned musculoskeletal pain, and that back pain represented the majority of those visits.7 In comparison, back pain in adults is much more prevalent; it is somewhere between the third and fifth most common reason to seek medical care in this country. Sixty percent of adults have significant back pain that requires absence from the workplace. There is some evidence that children with back pain are more likely to have back pain as they progress into adulthood.8 Hence, it may be important to selectively evaluate children and make accurate diagnoses and recommendations; it is hoped that this may reduce recurrent back pain as these patients become adults. Of note, children with psychosocial problems, and particularly conduct disorders,6 have a relative risk of up to 2.5 for the development of low back pain. If the back pain or pain syndrome is diffuse and widespread in various body locations, there will be a markedly increased rate of psychological overlays that may be a component of the child's pain syndrome.9
Roth-Isigkeit and coworkers10 studied 749 German children ages 10 to 15 and asked how many had recurrent or chronic pain during the last three months. They found that 83% had experienced pain over that time period, and 30% reported their pain had been present for more than six months. Headache (60%), abdominal pain (43%), limb pain (34%), and back pain (30%) were the most common pain locations; however, only 10% of these adolescents listed back pain as their most bothersome symptom. Eighty-five percent of the study population reported pain in more than one location, and 55% of these children visited a doctor for back pain. Surprisingly, only 16% reported self use of over-the-counter (OTC) pain medications.
Several issues in our culture may explain an increasing prevalence of back pain: the rising prevalence of childhood obesity,11-13 decreasing physical activity,13 and increasing sedentary activities like video games and computer activities.14 This, in turn, is creating a cycle of poor core muscle strength and increasing levels of back pain.15 Also, students now often carry heavier backpacks. This has pushed the American Academy of Pediatrics to issue guidelines that the weight of book bags should not exceed 10% of the body weight of the child or adolescent.16 Skaggs and colleagues17 looked at a population of 1540 children in southern California, where 97% of the children used backpacks. They found that back pain was associated with younger age (their cohort was 11 to 14 years old), being female, carrying a heavier backpack, and a positive screen for scoliosis. Of the 37% of these children who reported back pain, one-third of them limited their activity because of the back pain, but only 14% used medication for pain relief. Moore and associates18 studied the issue of whether to use 10% or 15% of body weight as a cutoff for the safe weight of a backpack. They looked at 531 children ages 11 to 18 and found that 10% was a safe weight for backpacks. Children with heavier backpacks reported higher rates of upper and mid-back pain but not low back pain.18
Children are participating in organized sports earlier in their lives, and there is a tendency to select "your sport" at earlier ages to "become the best." Balague and colleagues19 reported that 24% of competitive athletes versus 16% of recreational athletes reported low back pain. Micheli et al20,21 compared 100 adults with low back pain with 100 adolescents younger than age 18 who were engaged in sports and had low back pain. Forty-seven percent of those children had a stress fracture of the pars interarticularis or spondylolisthesis, while 48% of the adults were determined to have mechanical low back pain. The clinician should consider those child athletes who encounter higher vertebral column loads as having increased risk of stress fractures and back injuries.
Since back pain, even in children, is going to reflect inflammation in the anatomy of the back and often muscle spasm, the clinician seeing children should develop a treatment strategy that will address this inflammation and pain to allow the child to return to normal school and athletic function as soon as possible. The clinician should attempt to determine which children harbor back pathology that might progress or lead to recurrent or chronic back problems. It is important for the clinician to develop a framework to select pediatric patients who represent a more urgent or threatening problem that requires imaging or specific treatment strategies. The literature on the etiology of back pain in children is confusing. Turner et al1 and King22 cited that 6% to 10% of pediatric back pain in a series of children evaluated in tertiary referral orthopedic centers was caused by tumors. However, there was selection bias and physicians in primary care and emergency department physicians have lower incidences. Feldman and coworkers23 noted that at the Hospital for Joint Diseases in New York children with back pain were undergoing detailed investigations because of the perception that a high percentage would have treatable spinal conditions. This group looked at 217 consecutive children with an average age of 13 who had bone scintigraphy (single photon emission computerized tomogram, SPECT), a nuclear medicine study with tomographic slices for evaluation of their back pain. Seventy-eight percent of the children had no specific diagnosis to explain their back pain, 7% had spondylolysis, fewer than 5% had a tumor, and 10% had a variety of orthopedic diagnoses. In another study, during a one-year period, the emergency department of the Children's Hospital of Philadelphia described 225 children with a mean age of 12 who presented with back pain; this represented only 0.4% of all visits to their emergency department.24 Fifty-nine percent had pain for less than or equal to two days, and only 12% had pain for more than four weeks. Only 16% of the children had radiographs taken during the visit, with only two patients having clinically significant abnormalities.
It is critically important to consider a study's demographics, including the age, gender, and activity levels of the children; whether the setting is a primary care clinic or emergency department versus subspecialty clinic; and the length of time the patients report having had back pain symptoms. These considerations will guide the clinician in determining whether imaging is necessary. The purpose of this article is to provide some basis for making these decisions.
Diagnosis
Similar to the evaluation of headache, the correct diagnosis of back pain principally is a function of a careful and focused history. The history components should include the following questions.
1. Exactly where does it hurt?
2. Does it come on abruptly with activity?
3. Does it radiate (e.g., anterior to the trunk, down to legs, or into upper back)?
4. Does motion and bending worsen the pain, or is it equally bad at rest?
5. Does it wake you up, or keep you up at night?
6. Do you have any numbness, weakness, tingling, or bowel/bladder incontinence?
7. How long has this been going on, and has it changed over this time period?
8. Are there postural issues that play a role (e.g., television time, video time, or computer or phone time)?
9. Do you play sports? If so, what specific motions are required, especially involving the area(s) that hurt?
10. What medicines have you taken for the pain? How much do they help?
11. Have you traveled recently? (Potts disease or TB of spine are a possibility if the patient has traveled to an endemic area and has systemic symptoms.)
12. Do you use any injectable substances? (There's an increasing incidence of anabolic steroid use among teenagers; epidural abscesses have been reported to result from poor needle hygiene.)
These questions generally will provide a rather narrow differential diagnosis and allow the clinician to decide whether additional investigation is indicated.
What are the red flags in the history and examination of the patient that suggest diagnoses other than nonspecific and benign back pain? (See Table 1.)
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1. History of a significant traumatic mechanism resulting in moderate to severe back pain (a compression fracture or spondylolysis).
2. History of cancer.
3. Focal pain over a vertebral body, especially if it is severe or not associated with paravertebral muscle spasm.
4. Back pain associated with constitutional symptoms like fever, weight loss, decreased appetite, etc. (This may indicate diskitis, epidural abscess, osteomyelitis, tuberculosis, rare pediatric neoplasms, or rheumatologic causes.)
5. Back pain causing awakening from sleep (classically indicates osteoid osteomas, osteoblastomas, and rarely metastatic bone disease).
6. Any neurological symptoms (e.g., weakness, asymmetry of deep tendon reflexes, or persistent sensory symptoms), or new bowel or bladder dysfunction (e.g., herniated disks, syringomyelia, rarely cauda equina).
7. Any back pain radiating into the anterior abdomen (e.g., pancreatitis, gall bladder, nephrolithiasis, or a dorsal root sensory change at a higher vertebral level, including herpes zoster).
Physical Examination
The exam of the back in children and adults is straightforward. Clinicians should begin the exam with the patient relatively unclothed to allow visual inspection of the spine, hips, and legs from the shoulders down to the feet.
Inspect the patient's posture while standing behind the patient. Note the symmetry of the shoulders and the scapula. Note the thoracic curve; is it straight or an exaggerated curve (e.g., flexible kyphosis or Scheuermann syndrome)? Note the lumbar curve; is it straight (often muscle spasm or fusion) or excessively curved (normal at young ages and a risk for spondylolysis at older pediatric ages)? Note the posterior iliac crests for symmetry. Leg length discrepancies can cause a pseudo-scoliosis picture. If needed, measure the length of the legs from the anterior iliac crest spine to the bottom of the fibular head bilaterally. Orthopedic surgeons will measure radiographs to be more accurate.
Clinicians should then observe the spine for a hairy patch, as diastematomyelia syndromes (congenital split in spinal cord), syringomyelia (cavity in the spinal cord), and tethered cords can present with back pain or spinal curvature. Observe for café au lait pigmentation; neurofibromatosis can be associated with scoliosis.
The patient should then be asked to bend forward with his/her legs kept straight; this is called the Adam's test. The patient should be observed for either scoliosis or kyphosis.
Evaluate the hamstrings for tightness. Girls typically have significantly more flexibility (>70 degrees) in hamstrings than boys (generally < 60 degrees).
Note where the patient has maximal tenderness on their back. If it is over a bone prominence, consider a specific bone inflammatory condition. More diffuse pain often is secondary to muscle spasm. Observe whether it is at multiple levels or just at one place.
Then ask the patient to walk in the exam room. Biomechanical problems are a common cause of back pain in teenagers and adults. Observe the patient for normal heel to toe, antalgic cadence, pronator or supinator gait pattern, and symmetry. Then test strength with the patient standing. Observe the patient completing a squat/deep knee bend to demonstrate good pelvic flexors. (Quadriceps is L4.) Dorsiflexion of foot to walk on heels signifies that ankle dorsiflexors are intact (L5). Toe risers (stand on tip toes) means that ankle flexors are intact (S1).
The lumbar hyperextension test is performed with the patient standing, with passive and slow mobilizing of the back over the full range of motion of extension, with the knees in extension. The test is positive if sciatica is reproduced. However, sacroiliac (SI) inflammation will elicit pain, too.
SI joint dysfunction can be tested with the stork test:
1) The patient should be standing, with the examiner sitting behind and the examiner's left thumb placed over the most posterior portion of the left posterior superior iliac spine (PSIS) and his/her right thumb overlying the midline of the sacrum at the same level.
2) The patient should raise and flex the left hip and knee to a minimum of 90 degrees of the hip flexion making an "L" with the leg and thigh.
3) A negative test finds the left thumb on the posterior superior iliac spine (PSIS) moving caudad (towards the tail) in relation to the right thumb on the sacrum.
4) A positive finding occurs when the thumb on the PSIS moves cranially (toward the head) in relation to the thumb on the sacrum.
The stork test is more specific for SI joint restriction; however, it often will be positive, with symptomatic spondylolisthesis on the side of loading body weight. If the patient has difficulty standing on one foot to perform the test, proprioceptive sensory motor balance deficit should be further evaluated.
The Schober test is a useful measure of lumbar spine flexion. Place a horizontal line between the two posterior superior iliac spines. Place a mark 10 cm above and 5 cm below this line. Ask the patient to bend forward maximally, and measure the distance between the two lines. Normal mobility is represented by an increasing distance > 5 cm.
Then clinicians should ask the patient to sit on the table. Their mobility and fluidity in getting up on the table should be observed.
The patient's knees should be examined for effusions, warmth, or crepitus. Ask the patient to perform a straight leg raise from the sitting position to elicit pain or radicular symptoms. Evaluate the patient's distal tendon reflexes (DTRs). Knee jerk (patellar reflex) is L4, and ankle reflex is S1. If the patient has no discernable DTRs, ask him/her to hold their hands clasped together, and pull outwardly on the count of three. After the count, the DTRs should be rechecked. This will commonly disinhibit the patient and produce a normal DTR in otherwise "areflexic" patients.
Also ask the patient to lie on the exam table; observe him/her for pain.
Check straight leg raises (SLR, Lasegue's sign) for radicular symptoms. Raise the affected leg passively, with the patient relaxed and the knee in full extension. The sign is positive only if sciatica is reproduced. Observe the patient's range of motion at the same time. SLRs producing pain at 30 degrees signify hip involvement or a very inflamed nerve; at 30 to 60 degrees signifies sciatic nerve involvement; and 60 to 90 degrees signifies SI joint, lumbar joint, or hamstrings pathology.
Then check the patient's hips for internal and external rotation and pain.
Perform the pelvic ring compression test by pushing out and down on the superior anterior iliac crests and determine if it elicits pain in the sacroiliac joints or in the back.
Also, examine the patient's abdomen for masses or tenderness, particularly in the lower quadrants bilaterally, and check for inguinal lymph nodes that might signal another process.
With this sequence of examination performed, coupled with a detailed history, the clinician should have considerably narrowed the differential diagnosis.
Diagnostic Testing
Diagnostic testing will be needed for evaluation of children with any red flags and considered in children with pain persisting more than four weeks. Plain radiographs will detect fractures, abnormal lesions (either lytic or blastic), and congenital skeletal abnormalities. Discogenic problems, such as diskitis or herniated nucleus pulposis (ruptured disks), early stress fractures, or early osteomas, likely will not be seen on plain films. Oblique views of the lumbosacral spine may visualize spondylolisthesis and spondylolysis, which may be missed in up to 40% of anterior-posterior and lateral lumbar spine radiographs. Oblique views also are helpful for the evaluation of facet pathology; this may be a common site of pain in active children. Spondylolysis is one of the more common causes of chronic back pain lasting more than 4 weeks in teenagers.
MRI or biopsy can be completed for more specific diagnoses. Radiologic imaging using MRI of the back will provide excellent information about disks, disk inflammation, disk herniation, and end-plate infection, as well as excellent imaging of the spinal canal, spinal cord, and any impingement of the cord or spinal nerve roots exiting from the foramina.25 Bone scans, particularly single photon emission tomography (SPECT), may be useful for evaluating pediatric patients. They are especially helpful when there is a suspicion for stress fracture, osteomyelitis, metastatic tumor, and other findings.26
Laboratory tests usually are not needed; however, in the setting of constitutional symptoms and/or other red flags, clinicians should consider a complete blood count (CBC, with differential WBC) and a Westergren erythrocyte sedimentation rate (WSR) and/or C-reactive protein (CRP). If there are rheumatologic considerations, clinicians might add a rheumatoid factor, antinuclear antibody (ANA) test, or HLA B27 antigen, but rheumatologic conditions uncommonly present with isolated back pain.
Conditions Presenting as Back Pain in Children
The clinician should organize the differential diagnoses based upon the detailed history as the prime determinant. (See Table 2.) The physical exam will serve to corroborate and evaluate those symptoms. Focus the evaluation on discerning conditions that are urgent, unstable, or dangerous. For this discussion, back pain will first be discussed in the context of urgent diagnoses.
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Epidural Spinal Cord Compression Syndrome (ESCC). This syndrome is rare in children and uncommon in adults, but is a neurological emergency. Up to 20% of adult neoplastic metastases can present as an ESCC. Children can present with tumor or an epidural abscess. Typically, the patient will present with back pain for several weeks that is gradually progressive as the tumor or disk cause more epidural compression and inflammation. There frequently is supine pain. Weakness in both lower extremities is the key finding and can initially be subtle. If the compression is at the L1 level or below the conus medullaris (the horse's tail), there will be depressed deep tendon reflexes. If the compression is higher in the spinal cord, the examiner will see hyperreflexia and extensor plantar response. Sensory findings usually are present and the clinical dermatome levels usually are about one to five vertebral levels below the actual compression level. Cauda equina syndrome develops a saddle distribution paresthesia. Bladder dysfunction is a late finding; however, since diagnosis is typically delayed for weeks, this is seen in up to 50% of cases. Cauda equina syndrome and ESCC are indications for immediate radiologic evaluation, with MRI of the spine being the diagnostic method of choice, and then emergency neurosurgical consultation.
Disc Herniation. This is relatively common in adults but only 1-4% of disk herniations occur in adolescents. Diagnostic delays in teenagers occur; radicular symptoms are less common. (See Table 3.) Plain films done initially will be normal. The patient may have symptom resolution with posture cues, NSAIDs (non-steroidal anti-inflammatory drugs), and avoidance of activities that worsen the pain. If significant pain persists, radicular symptoms do not improve or progress, or particularly if motor weakness is demonstrated, then MRI of the lumbar spine would be indicated to evaluate for disc herniation, typically at the L4-5 or L5-S1 levels. Salminen and colleagues describe a prospective nine-year follow-up study of 40 14-year-old children (out of a cohort of 1400 students with recurrent back pain).8 MRI of the lumbar spine was completed at ages 15 and 18, with questionnaires about back pain and disability obtained at those ages and at age 23. Thirty-five percent of this group with recurrent back pain continued to complain of back pain. Those teenagers with degenerative disks seen at the initial age 15 study had a relative risk of chronic back pain that was 16 times that in those without disk degeneration by MRI evaluation. The authors conclude that disk degeneration soon after the phase of rapid physical growth not only increases the risk of low back pain, but also predicts recurrent back pain into young adulthood.
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Thoracic and Lumbar Fractures. These traumatic injuries are uncommon in children, with most being caused by the flexion distraction (whiplash) injuries of automobile accidents or major falls.27-29 Because the disk is stronger than cancellous bone in children, the vertebral body is the first element of the spinal column to fail during major compressive trauma. Compression fractures usually present as acute and localized back pain. They rarely exceed more than 20% of the vertebral body height; if it exceeds 50%, there may be injury to the spinal cord and MRI of the spine should be obtained. Most of these fractures are treated with rest, analgesics, and bracing, with resolution over about four weeks. Apophyseal end plate fractures and slipped apophyses are injuries unique to older children and teenagers whose symptoms will mimic a disk herniation. The most common site is at the caudal endplate of L4 and the patient may present with sensory changes, absent reflexes, and/or root tension signs. Diagnosis will be made by MRI of the spine. In infants and children younger than age 5, non-accidental trauma (child abuse) may be the cause of spinal trauma. Avulsion fractures of spinous processes of multiple vertebral bodies, fractures of the pars or pedicles, and compression fractures will be seen. Often, skull fractures or rib or long bone fractures of varying ages also are seen, and these are almost pathognomonic for this relatively common problem of non-accidental trauma.
Tumors. Bone tumors in children are rare, with data from Sweden reporting the overall incidence of malignant bone tumors to be 2.8 cases per million children with osteosarcomas, 2.2 cases per million for chondrosarcomas, and less than 1 per million for Ewing's sarcoma. The benign tumors are two to four times more common.30 The most common benign tumors of the spine are osteoid osteomas and osteoblastomas. Most of these vascular osteoid masses are in the long bones and lower extremities, with half involving the tibia or femur. The typical age group includes those in the first three decades of life. Painful scoliosis or stiffness with night pain that is relieved with NSAIDs is a typical presentation of spinal osteoid osteomas. Osteoblastomas include these same lesions, but they are at least 2 cm or greater in diameter and they do not respond to NSAIDs like the smaller osteoid osteomas.30 Aneurysmal bone cysts also can cause back pain that is typically chronic. Neoplastic disease is rare but the majority occur in children younger than age 10. Leukemia is the most common neoplastic disease of children, and Rogalsky and colleagues looked at 22 of 107 children with leukemia who presented with some musculoskeletal pain.31 Six children had pain localized to the spine, and the remaining 16 had extremity pain. Importantly, 80% of these children also had constitutional symptoms at presentation. Mehlman and associates looked at a retrospective series from Cincinnati Children's Hospital that included 16 malignant and 36 nonmalignant tumors of the vertebra and spinal cord.32 The initial radiographs were positive in 82% of those patients.
Diskitis. Inflammatory diskitis may present with focal or severe back pain, associated low-grade fever, and malaise. Typically children present at a mean age of 7; clinically, these patients do not usually appear toxic. Labs may show a normal to mildly elevated white blood cell count, and generally an elevated WSR or CRP. Some authors believe that this process begins near the end plate of a vertebral body, but plain films usually are normal early in the course. MRI of the spine will show inflammatory changes. (See Figure 1.) There is controversy about the etiology of diskitis, and different authors debate how many of these cases represent an attenuated bacterial infection. Disc biopsy was only positive in 25% of cultures33 but the most common organism is Staphylococcus aureus. Several authors, therefore, recommend parenteral antibiotics that cover S. aureus, as well as observing the patient's clinical response. Bracing may also be considered.
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Spondylolysis and Spondylolisthesis. These terms specify a defect in the pars interarticularis, usually involving the L5 vertebral body slipping forward on the S1 vertebral body. "Lysis" implies a fracture, whereas "listhesis" is the condition of the fracture (usually bilateral) leading to a slippage of the lower vertebral body on the one above it. (See Figure 2.) It is rarely seen in patients younger than age 5, and is most commonly seen in adolescents involved in sports during which there is load bearing on the spine that creates a stress fracture through repetitive exercise. This is seen more commonly in gymnasts, football players, and in those playing other impact sports. There often is no specific history of injury; patients may present with a complaint of low back pain. The defect on plain films is the classical "scotty dog" sign in which radio-opacity of the pars interarticularis is seen best on oblique films of the lumbosacral spine.34 (See Figure 3.) Spondylolisthesis is classified according to the degree of slippage of L5 forward on S1. There are four grades, with grade one representing less than 25% of the upper vertebral body slipping forward and grade four representing more than 75% slippage. The angle of the pelvis and the measure of lumbosacral kyphosis can help determine the likelihood of progression to higher grade slippage. The bony maturity of the patient also plays a role in determining the likelihood of progression; children who are still growing are at higher risk. The severity of clinical symptoms does not correlate with the degree of slippage and most patients have grade one findings that generally are clinically stable. For spondylolysis and grade one spondylolisthesis, the usual care is lumbar strengthening and general core strengthening unless an acute stress fracture is identified. In that case, bracing support and a period of rest for healing are indicated. Patients usually can then resume all activities. Surgical intervention for chronic pain and spondylolistheses of greater than 25-50% is not common; however, skeletally immature patients with grades three or four spondylolisthesis are at significant risk of progression and need to consider fusion for vertebral stabilization.
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Syndromes of Curvature of the Back. As noted earlier, kyphosis and scoliosis are major causes of back pain in children. Scoliosis is defined as a Cobb angle of greater than 10 degrees and axial plane rotation. The Cobb angle is the radiographic measurement created by drawing a perpendicular line through the distal endplate of the superior vertebral body involving the curvature to the distal endplate to the perpendicular line through the distal endplate of the inferiorly vertebral body of the curve. (See Figure 4.) Adolescent idiopathic scoliosis is the most common form, with an incidence of 2-3% for curves of 20-30 degrees and an incidence of 0.3% for curves of greater than 30 degrees. The incidence in males is equal to that in females for small curves, whereas the incidence of curves greater than 30 degrees has a ratio of 10:1 females to males.
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It is useful to categorize these curvature syndromes into: 1) postural round back; 2) Scheuermann kyphosis; 3) idiopathic scoliosis; 4) congenital scoliosis; and 5) neuromuscular scoliosis. Some authors35 describe compensatory scoliosis as the appearance of asymmetry on the forward flexion bending test (Adam's test) due to leg length discrepancy. This term is a misnomer, as the spine itself is within normal limits. Differences in leg length of just 0.5 cm may produce asymmetry, and leg length discrepancies are not uncommon. Clinicians screening children for scoliosis must be aware of this reason for a falsely positive Adam's forward-bend test, and look carefully at the alignment of the posterior superior iliac spines in these situations, consider a leg-length discrepancy, and consider a referral to a specialist. Remember that patients also can have leg-length discrepancy and scoliosis. So consider radiography in these children if it is clinically indicated.
The convex alignment of the thoracic spine has a range of curve from 20 to 40 degrees, as measured from the base plate of the lower thoracic vertebrae to the upper thoracic vertebrae. Children, and particularly teenagers, with a more accentuated curve will clinically have a round back. One can determine clinically whether it is flexible, in which case it is termed a flexible kyphosis. It also may be structural, in which case it would be classified as Scheuermann kyphosis. Flexible kyphosis will not demonstrate significant vertebral abnormalities on radiographs and supine hyperextension films show almost complete correction; hence, the term "flexible." Thoracic extension exercises and posture cues will help if there is associated back pain. This condition is seen in families.
Scheuermann kyphosis connotes nonflexible kyphosis that develops in adolescence.36 The curve typically is more than 45 degrees. The cause is unclear, but a suggested mechanism is a disordered pattern of endochondral ossification similar to that found in slipped capital femoral epiphysis.35 The classic form has at least three vertebral bodies that contain more than 5 degrees of wedging and it is most common in the mid thoracic level. Narrowing of intervertebral space; loss of vertebral height; and irregularities of the end-plates, called Schmorl nodes, frequently will be seen. The usual clinical presentation is thoracic back ache, back fatigue, or parents bringing their child into the office because of "bad posture." The physical exam is confirmatory, but anteroposterior (AP) and lateral films of the spine may be taken along with a hyperextension view to determine flexibility if clinically indicated. Hyperextension views of the kyphosis usually are less than 20 degrees and treatment is spinal extension muscle strengthening. Symptomatic patients with kyphosis of more than 45 degrees may benefit from bracing, especially for younger skeletally immature patients such that progression is retarded until the growth plates of the vertebral bodies fuse. A familial history is present in some cases. In the skeletally mature teenager or adult, curves of 70 to 80 degrees usually do not progress and usually do not cause functional problems.
Idiopathic scoliosis is the most common form of scoliosis, and this is the reason to screen all school age children as part of a well child physical exam. Idiopathic scoliosis is further divided into infantile (birth to age 3 and rare), juvenile (ages 4-10 and uncommon), and adolescent. The key is to examine preteens and early teenagers for scoliosis, because the curve may progress more rapidly during the adolescent growth spurt before the growth plates close. Remember that peak growth velocity (approximately 10 cm per year) occurs just before the onset of menarche in females and at the time of adrenarche and testicular gonadal development in males. The Adam's test for standing forward flexion will catch almost all children with more than 20 degrees of curvature (about 2-3% of the at-risk population). If needed, the radiology evaluation should include a standing AP and lateral whole spine views measuring the Cobb angle as discussed. (See Figure 4.)
Curves of less than 30 degrees rarely progress after skeletal maturation is complete,35 whereas curves of greater than 45 degrees often progress as the patient gets into adulthood. Curves of less than 25 degrees can be observed clinically. Bracing often is used for children with curves of greater than 30 degrees or curves of 25 degrees that progress more than 5 degrees annually. Patients with curves of greater than 45 degrees may be considered for surgical correction, and curves of less than that are usually treated with active bracing. Although bracing does not impact the degree of curvature, it may address back pain symptoms and help stabilize the skeletally immature spine. Surgical treatment is considered for curves of greater than 45 degrees with internal fixation and often posterior vertebral body fusion.37 Clinicians should refer patients to an orthopedic surgeon with experience in scoliosis for curves of greater than 25 degrees. Patients with scoliosis need to have an organized clinical evaluation to exclude neural axis abnormalities.38
Congenital scoliosis is a different entity. There is a developmental abnormality of vertebral body formation, failure of segmentation, or both. Spinal dysraphism, which implies spinal cord defects, is present in up to 40% of these infants.38,39 These abnormalities become evident on prenatal ultrasound, on newborn exam, or early in the first year of life. Twenty percent of these children have congenital urinary abnormalities, with renal agenesis being the most common renal anomaly. There may be tethering of the spinal cord and sacral or spinal cord lipomas seen as well. About 75% of these infants do have progression, especially during the two periods of rapid growth: before age 2 and after age 10. Many of these children will require anterior and posterior fusion procedures.
Neuromuscular scoliosis describes progressive spinal deformities that are seen in children with cerebral palsy, muscular dystrophies, spinal muscular atrophy, and related disorders. It is becoming more common with the growing number of children who have increased survival with chronic neuromuscular disease. The degree of evolving spinal vertebral scoliosis is roughly proportional to the severity of the weakness and progression of the neuromuscular disease. Non-ambulatory children with more profound neuromuscular diseases are at especially high risk. Many children with muscular dystrophies and spinal muscular atrophy will develop profound kyphoscoliosis curves that may require surgical intervention both to maintain the function of sitting in a wheelchair and preserve pulmonary function.
With scoliosis syndromes, consider MRI of the spine when there is an onset of scoliosis at younger than age 8, rapid curve progression of more than one degree per month, any neurological deficits, or persistent pain syndromes.
Treatment of Back Pain
The etiologies of back pain in children are quite diverse, but the majority of children will have musculoskeletal back strain, either isolated or with some curvature component, spondylolisthesis, or other non-operative conditions. Several authors have studied the epidemiology of back pain in teenagers and the related natural history of back pain as they grow into their third decade of life. As mentioned, Salminen presents evidence that disk disease in teenagers creates a substantial risk for recurrent back pain into the twenties.8 Hestbaek and coworkers40 looked at an eight-year prospective study in which back pain in children and adolescents predicted back pain in young adults. They commented that this should lead clinicians to focus on the young population in terms of etiology of back pain, treatment, and prevention. To date there are no data about prevention of this common problem. The question is how to prevent disk degeneration and spondylolysis in children, particularly in adolescents.
There is a lack of pediatric age group research, particularly randomized controlled trials (RCTs), of treatment of pediatric back pain. Van Tulder and Koes41 reviewed the literature looking for evidence-based medicine on the treatment of adult low back pain, defined as pain below the costal margin and above the gluteal folds, with or without sciatica not attributable to a recognizable pathology. They made the following observations. Ninety percent of adults recover within six weeks, although 2-7% develop chronic pain. Chronic back pain RCTs showed analgesics to be less effective than NSAIDs. Antidepressants did not demonstrate efficacy to relieve pain or depression with chronic back pain. Muscle relaxants seem to reduce low back pain but had no impact on outcomes. Epidural steroid injections were not effective in the absence of sciatica, and there was no evidence that facet injections reduce pain or improve function. Being advised to stay active was shown to improve the rate of recovery and reduce chronic disability, as well as to reduce time missed from work. Two adult RCTs have shown that behavior therapy reduces acute low back pain more than traditional care or EMG biofeedback. Exercise had been shown to be effective in reducing low back pain. There is conflicting evidence concerning the use of massage treatment, and there is no evidence on the efficacy of transcutaneous nerve stimulators (TENS) or acupuncture.
Some of these modalities may have a role in specific patient types, but overall a supportive approach to children with back pain is appropriate when the etiology is non-surgical. The intermittent use of NSAIDs can be considered and is probably more effective for musculoskeletal pain in children than acetaminophen.42 A program of strengthening core muscles with maintenance of hamstring and pelvic flexibility can be included. Physical therapists may be helpful in designing a treatment and strengthening plan. The general principles of treating recurrent back pain include the components of: 1) core muscle strengthening; 2) work on rectus abdominus (anterior spine stabilization); and 3) lower paraspinal muscles strengthening (posterior spine stabilization). In males, hamstring flexibility should be emphasized to provide more pelvic mobility with sports and lifting posture. Paraspinal strengthening is accomplished by kneeling on the ground in the dog position, then extending the right arm and the left leg simultaneously to the horizontal level for 5 to 10 seconds with extension, and doing repetitions as tolerated with a goal of 20 in a row. The exercise should then be repeated with the opposite arm and leg. Advice about lifting, back dynamics, and posture cues that might prevent or reduce recurrent back pain usually are helpful. These elements of strengthening the back have to be considered in the context of the age of the patient being treated. Evaluating how back pain impacts the child's life and helping them develop behavioral strategies to cope with this can be an important part of the treatment plan.
Summary
The prevalence of back pain in children varies with the age of the child, with adolescents representing the largest group of children with recurrent back pain. Conversely, when a younger child presents with back pain, the clinician is more likely to uncover a specific problem. Glorieux and coworkers30 divide the etiologies of back pain in children into: 35% developmental problems (kyphosis > scoliosis); 35% trauma (spondylolisthesis > fracture or soft tissue disruption); 15% spontaneous (infection, tumor, etc.); and 15% functional. Clinicians should keep in mind that muscle fatigue and postural issues that often accompany some type of curve such as flexible kyphosis or Scheuermann syndrome make up a large group of children with low back pain who present to primary care providers. The second largest group to consider is spondylolisthesis, especially in athletically active teenagers who impose loading dynamics on their vertebral column. Psychological stressors may accentuate underlying low back pain, especially if the pain syndrome involves several different anatomic areas. Primary care and emergency medicine physicians may see an even higher percentage of non-specific back pain with children who have a psychological overlay to their pain syndrome.
A specific history and physical exam will help the clinician narrow the differential diagnoses. Maintaining vigilance for the "red flags" in the evaluation of back pain is an important element in the recognition of potentially serious etiologies of back pain in children. When appropriate, plain radiographs of the back are recommended as a starting point. MRI of the back has become the most specific imaging modality. MRI can be a useful adjunctive imaging modality when plain films are negative and the clinician still has a suspicion for bone or skeletal pathology.
It is important for the clinician to thoroughly understand the differential diagnoses and prevalence of back pain in children to make appropriate decisions concerning evaluation and care.
Note from the author: I would like to thank Dale Newton, MD, FAAP, Vice Chairman, Department of Pediatrics, Brody School of Medicine, East Carolina University for his input, assistance, and editing comments for this manuscript; and Ron Perkin, MD, MS, FAAP, Chairman of Pediatrics at the Brody School of Medicine, East Carolina University.
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The incidence of back pain in children is directly proportional to the age of the child, with back pain an unusual complaint in children younger than age 6. There is a steady increase in incidence, with adolescents having the highest rates of back pain by the time they are age 18. Approximately 60% of adults experience significant back pain in their lifetimes.Subscribe Now for Access
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