Adolescent Idiopathic Scoliosis Case File
Eugene C. Toy, MD, Andrew J. Rosenbaum, MD, Timothy T. Roberts, MD, Joshua S. Dines, MD
CASE 28
A 12-year-old girl is referred to your clinic for concerns of shoulder asymmetry. She states that her friends first noticed that her back was not symmetric when she was changing clothes for basketball practice. She notices occasional back pain that she attributes to carrying a heavy backpack. The review of systems is otherwise unremarkable. Her past medical and developmental history are also noncontributory. She is in the seventh grade and is active in athletics and gymnastics. She experienced menarche 4 months prior and her menses have been regular. On examination, her right shoulder is 2 cm higher than the left, but her posterior iliac wings are of equal and symmetric heights. She has mild tenderness to palpation and slight spasms of the paraspinal musculature of her right-sided thoracic spine. There are no cutaneous lesions in the midline of her back. On forward bending, she has a 7-degree angle of trunk rotation in the thoracic spine, with the right side higher than the left. She has 5/5 strength in bilateral lower extremities throughout all muscle groups and no sensory abnormalities. Knee and ankle jerk reflexes are 2+ and symmetric. She has no sustained clonus or pathologic reflexes.
► What is the most likely diagnosis?
► What is your next diagnostic step?
► What are the treatment options?
ANSWER TO CASE 28:
Adolescent Idiopathic Scoliosis
Summary: A healthy 12-year-old girl presents with mild back pain, shoulder asymmetry, and a 7-degree rotational deformity of her thoracic spine. She has recently experienced menarche and has no other complaints. Neurologic exam is unremarkable.
- Most likely diagnosis: Adolescent idiopathic scoliosis (AIS).
- Next diagnostic step: Standing 36-in posteroanterior (PA) and lateral spine radiographs.
- Treatment options: Observation, brace treatment, surgical spinal fusion.
ANALYSIS
Objectives
- Understand the common presentation and characteristics of patients with AIS.
- Recognize pertinent negatives that distinguish idiopathic scoliosis from scoliosis caused by other etiologies.
- Consider the factors that lead to the decision making in the treatment algorithm of scoliosis.
Considerations
This 12-year-old girl depicts a classic presentation of a patient with AIS, a disease characterized by both abnormal curvature and rotation of the spine from an unknown cause. This is an otherwise healthy adolescent, like most patients with idiopathic scoliosis. This patient is also female, representing the 8:1 female-to-male ratio of patients with scoliosis large enough in magnitude to require treatment. Often, concerns of both patients and parents are not of pain or dysfunction, but of cosmetic appearance. Shoulder, trunk, and flank asymmetry can be very noticeable and can significantly harm the self-image of the patient. The goals of treatment are to prevent long-term complications of cardiovascular and pulmonary dysfunction, which tend to present later with curve progression in adulthood. Surgical intervention in adults carries greater risk of morbidity.
In addition to her deformity, the patient’s complaints of back pain should not be ignored. Although rare, physicians must first rule out potential pathologic causes of scoliosis, as AIS is a diagnosis of exclusion. Both the history and physical exam, with judicious use of radiologic and laboratory studies, should be used to evaluate for other potential causes of back pain, including osteomyelitis, discitis, spondylolysis, disc herniation, or even skeletal and mesenchymal-derived tumors.
Several red flags may arise in the workup of a patient with scoliosis that warrant further evaluation, including history of fever or constitutional symptoms, unexplained weight loss, neurologic abnormalities, pain unrelated to activity, and/or pain at night. Idiopathic scoliosis is typically characterized by thoracic dextroscoliosis, or a right-sided thoracic curve. Particular attention should be paid to atypical curve patterns such as levoscoliosis (left-sided curve), juvenile-onset deformities (< 10 years of age at time of diagnosis), hyperkyphosis (a sharp posterior- facing or “hunchback” curve), and large curves without rotational deformities. Spinal deformity can be the initial presenting complaint for patients with central nervous system anomalies such as Arnold-Chiari malformations, syringomyelia, diastematomyelia, tethered cords, or central nervous system tumors. Neuromuscular scoliosis is the second most common type of scoliosis, following AIS, and often occurs in patients with cerebral palsy, muscular dystrophy, and other neurologic disorders. Scoliosis may also occur secondary to underlying genetic diseases such as neurofibromatosis, Marfan syndrome, Ehlers-Danlos syndrome, osteogenesis imperfecta, or as secondary to previous spine trauma. On occasion, subclinical neuromuscular diseases such as mild cerebral palsy and Charcot Marie Tooth disease can remain unrecognized into adolescence but be an underlying cause of scoliosis. Alterations in the neurologic exam, unexplained pain, and atypical curve patterns should raise suspicion that the spinal deformity is not idiopathic. In such situations, the physician must obtain further diagnostic imaging such as magnetic resonance imaging (MRI) of the entire spine and/or ultrasound exams to evaluate for common congenital correlates to malformed vertebrae (ie, renal ultrasound, cardiac echocardiogram).
APPROACH TO:
Scoliosis
DEFINITIONS
SCOLIOSIS: Defined by greater than 10 degrees of curvature of the spine in the coronal plane. Although measured on a 2-dimensional x-ray, scoliosis is typically a 3-dimensional process with rotational deformities. It is commonly measured using the Cobb method.
KYPHOSIS: A deformity in the sagittal plane characterized by apex-posterior curvature of the spine. A small degree of kyphosis is normal and should measure between 20 and 40 degrees in the thoracic spine.
COBB ANGLE: The angle subtended by lines drawn through vertebral endplates at each point of curve inflection. Cobb angles are typically measured on standing full-length spine x-rays.
PEAK GROWTH VELOCITY: The skeletal growth spurt usually seen early in the second decade of life. Progression of scoliosis curves is at highest risk during this time.
RISSER SIGN: The ossification of the iliac apophysis, seen on coronal radiographs. Graded from 0 through 5, based on quartiles of the total length of the iliac crest with ossified from lateral to medial. Ossification is a marker of skeletal maturity and can thus be used to determine the likelihood of curve progression.
CLINICAL APPROACH
Etiologies
Scoliosis is defined by greater than 10 degrees of spinal curvature in the coronal plane; less than 10 degrees of curvature is termed spinal asymmetry. Although it is typically observed on 2-dimensional x-rays, scoliosis is actually a 3-dimensional rotational deformity of the vertebral column. Although adolescent idiopathic scoliosis is the most commonly seen presentation of scoliosis, it is a diagnosis of exclusion. To diagnose scoliosis, less common, but more insidious, causes must be investigated.
The etiology of scoliosis is best described as multifactorial. Hereditary studies have shown an increased incidence of scoliosis within families, but penetrance is variable. Several genes have been implicated in the etiology for scoliosis, but clinical results are inconclusive for a single gene responsible for the condition. Similarly, hormonal and neuromuscular etiologies have been implicated, but current research has failed to demonstrate conclusive independent causation.
Clinical Presentation of Scoliosis
The majority of patients with AIS present with complaints of cosmesis. Only in cases of severe curve magnitude (≥ 80 degrees) is evidence of cardiovascular or pulmonary dysfunction seen in adolescents. Often, patients’ curves have first been observed by classmates, physical education teachers, school nurses, or found incidentally on routine exams by pediatricians. Pain associated with scoliosis is common in adulthood but is rare in adolescence. Complete gestational and birth history as well as neurologic developmental milestone achievement should be reviewed, along with a detailed physical and neurologic exam at the initial visit. Radiographic imaging should be performed at regular intervals to monitor for progression of the curve with consideration given to the cumulative radiation dose to which the patient will be exposed.
TREATMENT
Treatment is defined by the likelihood of curve progression during both adolescence and adulthood. Most AIS patients are healthy and active despite sometimes pronounced deformities. When discussing the natural history of scoliosis with patients and their families, the consequences of curve progression into adulthood and its effects on cardiopulmonary health must be discussed. Such dysfunctions are often absent in the asymptomatic adolescent, but may manifest later in life with significant morbidity.
Generally, AIS patients with curves of less than 20 degrees are managed with clinical observation and intermittent radiographic follow-up if the curve is at high risk of progression. Brace treatment is indicated for AIS patients with curve magnitudes of 25 to 40 degrees and who are still growing. Patients most likely to benefit from bracing include premenarchal girls, girls or boys in or before their peak height velocity, or girls or boys with less than 50% of iliac apophysis ossification (ie, Risser stage of 0, 1, or 2). As stated, curve magnitude increases at the greatest rate during the period of peak growth velocity. Remember to discuss with patients that the realistic goal for brace treatment is not to correct the spinal curvature, but to prevent it from increasing in magnitude. The best prognostic indicator for successful scoliosis bracing is the ability to immediately improve the prebracing radiographic curve by 50% when the first brace is applied. Braces must be worn at a minimum of 16 to 23 hours per day, and, not surprisingly, patient compliance is a considerable issue.
Figure 28–1. Treatment of a scoliotic curve by instrumentation and fusion. (A) Preoperative view and
(B) postoperative view. (Reproduced, with permission, from Skinner HB. Current Diagnosis & Treatment in Orthopedics. 4th ed. New York, NY: McGraw-Hill; 2006:Fig. 11-36.)
AIS curves greater than 50 degrees are a potential indication for spinal fusion surgery. Natural history studies of AIS suggest the greatest increased risk of progression into adulthood when curves are beyond 50 degrees. The primary goal of AIS surgical treatment is to halt the progression of deformity by achieving a solid fusion of the spine. Additional surgical goals include the sparing of spinal motion segments wherever possible, obtaining a pain-free spine, and correcting as much of the curvature as is safely possible. Surgical spinal fusion typically involves a combination of bone grafting and instrumentation to fix the curved spine into a rigid structure. Surgical approaches may be posterior, anterior, or combined in cases of severe disease. Instrumentation used to hold the fusion may include rods, pedicle screws, hooks, wires, and other implants ( Figure 28–1 ).
Complications
Spinal fusion procedures are often long, painful, and highly morbid procedures with significant blood loss, requiring transfusion and/or the use of intraoperative blood salvage techniques. Early wound infection (1%-2%), pseudoarthrosis (1%-2%), painful prominent hardware, and hardware breakage are described complications. The most devastating but rare complication is iatrogenic neurologic injury. Intraoperative neurologic monitoring may help prevent this. A crankshaft phenomenon may occur when an immature spine is fused posteriorly, but continues to grow anteriorly, causing the expanding spine to spiral around the posterior fusion. This may be prevented with concomitant anterior fusion.
COMPREHENSION QUESTIONS
28.1 A 10-year-old healthy girl is referred to your office after testing positive for scoliosis during a schoolwide screening. Physical exam is unremarkable except for absence of her abdominal reflex on the right side. Standing 36-in scoliosis radiographs show a 25-degree levoscoliosis curve with minimal rotation and hyperkyphosis. She is Risser 0 developmental stage on x-ray. What is the next step in management?
A. Reassure and observe with clinical and radiographic examination in 3 to 4 monthsB. Fitting for a thoracolumbosacral orthosis (TLSO)C. Obtain a bone scanD. Obtain an MRI of the entire central nervous systemE. Book patient for spinal fusion after obtaining appropriate consent
28.2 A 15-year-old male athlete presents for evaluation of shoulder asymmetry pointed out by his football teammates. His mother had never noticed the discrepancy until now but is very concerned. The boy has a 15-degree right-sided trunk rotation on the Adam forward-bending test. His neurologic examination is unremarkable. Thirty-six inch PA standing scoliosis radiographs show a 60-degree right thoracic curve and shoulder elevation 2 cm greater on the right than left. What is the next step in management?
A. Trial nonoperative treatment with a thoracolumbosacral orthosis (TLSO)B. Reassure and observe patient with repeat clinical and radiographic evaluation in 3 to 4 monthsC. Obtain an MRI of the entire central nervous systemD. Obtain a bone scan and laboratory studies for evidence of underlying pathology including erythrocyte sedimentation rate, C-reactive protein, and complete blood countE. Book patient for spinal fusion after obtaining appropriate consent
28.3 A 15-year-old girl has asymptomatic adolescent idiopathic scoliosis. Her parents ask you how debilitated she might be compared with her peers who do not have scoliosis. Which of the following is true regarding the natural history of idiopathic scoliosis?
A. Difficulty with pregnancyB. Increased risk of developing cancerC. Acute or chronic back painD. Athletic limitations
ANSWERS
28.1 D. Atypical curve patterns require MRI evaluation of the spine and central nervous system for workup of underlying pathology. Bone scans, although useful for diagnosing infection or subacute bony injury, are not sensitive to other potential pathology etiologies. Bracing and observation are inappropriate without first ruling out a pathologic etiology.
28.2 E. Spinal fusion is indicated in curves measuring greater than 50 degrees. Although workup with MRI or laboratory studies is necessary when patients have evidence of pathologic etiology for scoliosis, patients without concerning symptoms do not require such an extensive workup. This patient’s curve is too great in magnitude to be managed with observation or with bracing.
28.3 C. Scoliotic patients have been found to have more acute or chronic back pain, as well as cosmetic concerns. Pregnancy complications, athletic limitations, and an increased cancer risk are not associated with AIS.
CLINICAL PEARLS
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► Adolescent idiopathic scoliosis is a diagnosis of exclusion, meaning physicians must rule out potential congenital, neuromuscular, traumatic, or syndromic etiologies before making the diagnosis. ► The risk of scoliosis curve progression is greatest during early adolescence when the peak growth velocity occurs. ► Among many non-AIS causes of back pain in adolescents are discitis, herniated disks, osteoid osteoma, lymphoma, and spondylolysis. ► Scoliosis bracing is indicated for adolescents in their peak height velocity or those who have not yet reached their peak height velocity, as well as patients with significant curve magnitudes (> 25-40 degrees) and those in Risser 0 through 2 stages of skeletal maturity. ► Spinal fusion surgery is generally indicated for patients with progressive curves greater than 50 degrees. |
REFERENCES
Cobb JR. Outline for the study of scoliosis. In: Thomson JEM, Boount WP, eds. The American Academy of Orthopaedic Surgeons. Instructional Course Lectures. Ann Arbor, MI: JW Edwards; 1948;5:261-275.
Miller MD, ed. Pediatric orthopaedics. In: Review of Orthopaedics . 5th ed. Philadelphia: Saunders Elsevier; 2008:198-244.
Sanders JO, Browne RH, Cooney TE, Finegold DN, McConnell SJ, Margraf SA. Correlates of the peak height velocity in girls with idiopathic scoliosis. Spine. 2006;31:2289-2295.
Song KM, Little DG. Peak height velocity as a maturity indicator for males with idiopathic scoliosis. J Pediatr Orthop. 2000;20:286-288.
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