Back pain in school-aged children is more common than previously suspected and will not yield a definitive etiology in up to 80 percent of patients. A workup rules in or out the 20 percent of etiologies needing a definitive diagnosis and/or emergent treatment. A workup is indicated for adolescents with chronic lower back pain lasting 4-6 weeks, or sooner for those with red flags such as:
- Lower extremity radiation or weakness
- Bowel/bladder incontinence or hesitancy
- Saddle anesthesia
- Fevers, night pain or weight loss
- Worsening or intractable pain
From a rheumatologic standpoint, a set of evidence-based questions will suggest an inflammatory etiology and steer the workup accordingly:
- Does back stiffness in the morning last more than 30 minutes?
- Does back pain awaken you during the second half of the night?
- Does the pain alternate from one buttock to the other?
- Does pain improve with exercise but not with rest?
When a patient with prolonged symptoms answers two of the four questions with a “yes,” the sensitivity and specificity for an inflammatory etiologic cause reach 70 percent and 81 percent, respectively. When answers to three of four questions are positive, the sensitivity drops to 33 percent while specificity approaches 100 percent.
Workup specifically for spondylolysis always starts with plain X-rays of the spine. The sensitivity of plain X-ray to accurately identify spondylosis is only about 50 percent, so if index of suspicion is high — persistent pain, especially with extension and in a high-risk sport that involves repetitive extension and rotation such as diving, gymnastics, dance, soccer, volleyball and basketball to name a few — then further imaging is indicated.
Controversy exists on which type of advanced imaging is preferred, SPECT bone scan versus MRI. Radiation stewardship is also important to consider as we think about the pros and cons of both modalities. I find it is also very institution-specific as to which imaging modality is preferred by the radiologists. Here are the advantages and disadvantages of both:
SPECT Bone Scan
- 95 percent sensitive
- Gives an accurate metabolic picture (bone edema)
- Paired with CT, it will tell you if a fracture is present vs. just bone edema
- Easily approved by insurance
- Radiation exposure, especially if paired with limited CT images
- Requires an IV for a short time and 2-3 hours at the hospital
- No radiation/no IV unless contrast is desired
- Can reveal other information about nerve roots, cord, etc.
- Will miss up to 20-30 percent of spondylolysis if they are subacute with minimal bone edema and even less sensitive for identifying fracture lines
- Insurance approval required and denials are common, necessitating physician to physician peer review
I go through this information with families. If patients have more flexion-based lower back pain, radiculopathy or concerning review of symptoms suggesting a possible tumor, mass, compression fracture or inflammatory etiology, then I will lean towards MRI. If families prefer to start with MRI, I will remind them that if the study is read as normal but their child is not responding positively to treatment, then we may circle back and obtain a bone scan.
To help you understand the complexities of pediatric back pain, I have referenced 5 articles, including a very thorough, recent systematic review in JAMA Pediatrics written by colleagues in our Section of Sports Medicine.
DePalma MJ, Bhargava A. Nonspondylolytic etiologies of lumbar pain in the young athlete. Current Sports Medicine Reports. 2006 Feb; 5(1): 44-9.
Garet M, Reiman MP, Mathers J, Sylvain J. Nonoperative treatment in lumbar spondylolysis and spondylolisthesis: a systematic review. Sports Health. 2013 May; 5(3):225-32.
Kim HJ, Green DW. Spondylolysis in the adolescent athlete. Current Opinion in Pediatrics. 2011 Feb; 23(1):68-72.
MacDonald J, Stuart E, Rodenberg R. Musculoskeletal low back pain in school-aged children: a review. JAMA Pediatrics. 2017 Mar 1; 171(3):280-287.
Taxter AJ, Chauvin NA, Weiss PF. Diagnosis and treatment of low back pain in the pediatric population. The Physician and Sportsmedicine. 2014 Feb; 42(1):94-104.