Left Upper Back Pain with Deep Breathing While Lying Supine
Your left upper back pain triggered by deep breathing while lying slightly on your back is most likely musculoskeletal (mechanical) in nature, but you need to be evaluated for several potentially serious conditions that can present this way, particularly if you have any red flag symptoms.
Immediate Red Flags to Assess
You need urgent evaluation if you have any of the following 1:
- Fever or recent infection (suggests possible spinal infection or epidural abscess) 1
- History of cancer (increases likelihood of spinal metastases from 0.7% to 9%) 1
- Unexplained weight loss (associated with malignancy) 1
- Intravenous drug use (risk factor for spinal infection and epidural abscess) 1
- Immunosuppression (diabetes, steroid use, HIV) - increases infection risk 1
- Neurologic symptoms (weakness, numbness, bowel/bladder dysfunction) 1
- Severe trauma history 1
Most Likely Diagnoses
Musculoskeletal/Mechanical Pain (Most Common)
Mechanical back pain accounts for 97% of thoracic back pain cases and arises from spinal structures including bone, ligaments, discs, joints, nerves, and muscles 2. The thoracic spine is particularly prone to:
- Muscle strain or spasm - worsens with certain positions and breathing movements 3
- Facet joint pain - can be position-dependent 2
- Rib dysfunction - the thoracic spine's unique articulation with ribs can cause pain with deep breathing 1
- Costochondritis or intercostal muscle strain 1
Inflammatory Conditions (Less Common but Important)
If your pain includes morning stiffness that improves with exercise, consider ankylosing spondylitis 4. Key distinguishing features include 1, 4:
- Younger age (typically <40 years)
- Morning stiffness across the whole back
- Improvement with exercise (pathognomonic for inflammatory spondyloarthropathy)
- Alternating buttock pain
- Awakening during the second part of the night due to pain
Serious Conditions Requiring Urgent Imaging
The thoracic spine is a common site for 1:
- Vertebral compression fractures (especially if >65 years, osteoporosis, or chronic steroid use) 1
- Malignancy (primary tumors or metastases) 1
- Spinal infection/epidural abscess (note: fever present in only 45% of cases, so absence doesn't exclude infection) 5
Clinical Approach
If NO Red Flags Present
Conservative management without imaging is appropriate initially 1:
- Relative rest while maintaining activity levels 2
- NSAIDs for limited duration 3
- Physical therapy if symptoms persist beyond 4-6 weeks 1, 6
- Imaging should be considered only after 4-6 weeks of failed conservative treatment 1
If Red Flags ARE Present
Immediate imaging is warranted 1:
- MRI without and with IV contrast of the thoracic spine is the preferred initial study for suspected infection, malignancy, or neurologic compromise 1
- CT thoracic spine if MRI contraindicated or for evaluating fractures 1
- Laboratory studies: CBC, ESR, CRP if infection suspected 1
Critical Pitfalls to Avoid
- Don't assume absence of fever excludes spinal infection - fever is present in less than half of vertebral osteomyelitis cases, and average time to diagnosis is 2-4 months 5
- Don't delay imaging in patients >65 years or with osteoporosis risk factors - thoracic spine is the most common site for osteoporotic compression fractures 1
- Don't miss cauda equina syndrome - urinary retention has 90% sensitivity; if present, this is a surgical emergency 1, 5
- Position-dependent pain with breathing doesn't exclude serious pathology - pleuritic chest pain can mimic musculoskeletal pain, and intrathoracic, renal, vascular, or gastrointestinal conditions can present as thoracic back pain 1
When to Seek Care
Seek immediate evaluation if 1:
- Pain persists beyond 4 weeks despite conservative treatment
- Any red flag symptoms develop
- Pain progressively worsens
- Neurologic symptoms appear
For uncomplicated mechanical pain, expect improvement within 4-6 weeks with conservative management 1, 6.