Causes of Referred Back Pain Between the Scapulae

Primary Etiologies

• The American College of Radiology suggests that intrathoracic, gastrointestinal, renal, and vascular pathologies commonly refer pain to the interscapular region through viscero-somatic convergent neurons in the spinal cord 1.
• Conditions such as pancreatitis, nephrolithiasis, aortic aneurysm, cardiac ischemia, and pleural irritation can cause referred pain to the interscapular region, as noted by the Annals of Internal Medicine 2.
• The thoracic spine is a common site for inflammatory, neoplastic, metabolic, infectious, and degenerative conditions, according to the Journal of the American College of Radiology 1.
• Thoracic disc herniations occur most commonly below T7, are often calcified (20-65%), and present with midback pain (76% of cases), motor/sensory deficits (61%), and spasticity (58%), as reported by the Journal of the American College of Radiology 4.
• Spinal stenosis from facet arthropathy, ligamentum flavum ossification, or disc herniations causes compressive myelopathy, as noted by the Journal of the American College of Radiology 4.
• Malignancy has a 0.7% prevalence in primary care back pain patients, increasing to 9% with prior cancer history, according to the Annals of Internal Medicine 2.
• Vertebral compression fractures occur in 4% of cases, particularly in patients >65 years or with chronic steroid use, as reported by the Journal of the American College of Radiology 1.
• Spinal infection has 0.01% prevalence but must be considered with fever, recent infection, IV drug use, or immunocompromised status, as noted by the Annals of Internal Medicine 2.
• Axial spondyloarthritis (axSpA) involves the thoracic spine and thoracolumbar junction as the most common sites of spinal involvement in a minority with isolated spine disease, according to the Journal of the American College of Radiology 6.
• Inflammatory back pain improves with exercise, worsens with rest, occurs at night, and has insidious onset before age 40, as reported by the Journal of the American College of Radiology 6.
• Bilateral sacroiliitis is typical, but isolated thoracic involvement occurs, as noted by the Journal of the American College of Radiology 6.

Red Flags Requiring Urgent Evaluation

• The American College of Radiology recommends immediate imaging with MRI when any of the following are present: history of cancer, unexplained weight loss, age >50 years, fever, recent infection, IV drug use, or immunocompromised status 1, 2.
• History of cancer increases the probability of malignancy to 9%, as noted by the Annals of Internal Medicine 2.
• Unexplained weight loss has a positive likelihood ratio of 2.7, according to the Annals of Internal Medicine 2.
• Age >50 years has a positive likelihood ratio of 2.7, as reported by the Annals of Internal Medicine 2.
• Fever, recent infection, IV drug use, or immunocompromised status require urgent evaluation, as noted by the Annals of Internal Medicine 2.

Diagnostic Approach

• The American College of Radiology suggests that no imaging is warranted for acute (<4 weeks) uncomplicated thoracic back pain without red flags or neurologic deficits 1.
• Conservative management with physical therapy and medical management should be attempted for 4-6 weeks, as reported by the Journal of the American College of Radiology 1.
• Consider imaging after 4-6 weeks if no improvement occurs with conservative treatment, as noted by the Journal of the American College of Radiology 1.
• MRI thoracic spine without contrast is the initial imaging modality of choice for evaluating myelopathy, radiculopathy, or suspected serious pathology, according to the Journal of the American College of Radiology 4.
• If visceral pathology is suspected based on clinical presentation, chest imaging (radiograph or CT) should be obtained, as reported by Praxis Medical Insights 3.
• Laboratory studies including CBC, ESR, and CRP should be obtained when infection or inflammatory conditions are suspected, as noted by Praxis Medical Insights 3.

Common Pitfalls

• Failing to recognize visceral referred pain patterns leads to delayed diagnosis of serious conditions like cardiac ischemia or aortic pathology, as noted by the Annals of Internal Medicine 2.
• Ordering imaging for acute uncomplicated thoracic back pain provides no clinical benefit and increases costs, according to the Journal of the American College of Radiology 1.
• Missing red flags in older patients (>65 years) who have higher risk for compression fractures and malignancy, as reported by the Journal of the American College of Radiology 1 and the Annals of Internal Medicine 2.
• Attributing all interscapular pain to musculoskeletal causes without considering inflammatory conditions like axSpA, especially in younger patients with characteristic pain patterns, as noted by the Journal of the American College of Radiology 6 and Praxis Medical Insights 3.