What are the possible causes and recommended evaluation for posterior thoracic (back side) pain that worsens with deep inspiration?

Back Side Pain with Inspiration: Diagnostic Approach

Posterior thoracic pain worsening with deep inspiration is pleuritic pain until proven otherwise, and pulmonary embolism must be excluded first as it is the most common serious cause, found in 5-21% of patients presenting with pleuritic chest pain. 1

Immediate Life-Threatening Causes to Exclude

The initial evaluation must focus on ruling out conditions that require urgent intervention:

Pulmonary Embolism (Most Common Serious Cause)

• PE is the primary concern in pleuritic chest pain and presents with dyspnea, pleuritic chest pain, tachycardia, and tachypnea in >90% of cases. 2, 3
• Use validated clinical decision rules (Wells criteria) to determine pretest probability before ordering additional testing. 2
• D-dimer testing with age- and sex-specific cutoffs is useful in low-to-intermediate pretest probability patients; negative D-dimer effectively excludes PE. 2
• CT pulmonary angiography (CTPA) is the primary imaging modality for patients with high clinical suspicion or positive D-dimer. 2

Pneumothorax

• Classic triad: dyspnea, pleuritic pain on inspiration, and unilateral absence of breath sounds with hyperresonant percussion. 3, 2
• Chest radiography is diagnostic in most cases. 3

Acute Coronary Syndrome

• Critical pitfall: 13% of ACS patients present with pleuritic pain, and 7% of patients with reproducible chest wall tenderness still have ACS. 3, 2
• ECG must be obtained within 10 minutes of arrival and cardiac troponin measured as soon as possible. 2, 3

Aortic Dissection

• Sudden onset "ripping" severe chest or back pain with pulse differential (30% of cases) and widened mediastinum on chest X-ray. 2, 3

Pericarditis

• Sharp, pleuritic pain that improves sitting forward and worsens supine, with pericardial friction rub. 2, 3
• ECG shows widespread ST-elevation with PR depression. 2, 3

Common Pulmonary Causes

Pneumonia

• Localized pleuritic pain with fever, productive cough, regional dullness to percussion, egophony, and possible pleural friction rub. 2, 3, 1
• Chest radiography is usually diagnostic, but in patients >50 years, smokers, or those with persistent symptoms, repeat chest X-ray at 6 weeks is essential to document resolution and exclude underlying malignancy. 1

Pleural Effusion

• Develops in 46% of PE cases and causes ongoing pleuritic discomfort. 3
• May be detected by chest radiography or ultrasound. 4

Viral Pleurisy

• Viruses are common causative agents: Coxsackieviruses, respiratory syncytial virus, influenza, parainfluenza, mumps, adenovirus, cytomegalovirus, and Epstein-Barr virus. 1
• Diagnosis of exclusion after ruling out serious causes. 1

Musculoskeletal Causes

Costochondritis/Tietze Syndrome

• Tenderness of costochondral joints on palpation. 2, 3
• Major pitfall: Chest wall tenderness does NOT exclude serious pathology—7% of patients with reproducible chest wall tenderness have ACS. 3, 2
• Important caveat: Pleurisy itself can cause chest wall tenderness through spinal reflex mechanisms, mimicking musculoskeletal pain. 5

Algorithmic Diagnostic Approach

Step 1: Immediate Assessment (Within 10 Minutes)

• Obtain ECG within 10 minutes to identify STEMI, pericarditis patterns, or signs of PE. 2, 3
• Measure vital signs: tachycardia and tachypnea present in >90% of PE cases. 3
• Perform focused cardiovascular and pulmonary examination. 2

Step 2: Initial Testing

• Chest radiography (PA and lateral) to evaluate for pneumothorax, pneumonia, pleural effusion, or widened mediastinum. 2, 3
• Cardiac troponin measurement as soon as possible in acute presentations. 2, 3
• Critical: A normal chest X-ray does NOT exclude PE or other serious conditions. 2

Step 3: Risk Stratification for PE

• Apply Wells criteria or other validated clinical decision rules. 2
• If low-to-intermediate probability: obtain D-dimer with age- and sex-specific cutoffs. 2
• If high probability or positive D-dimer: proceed directly to CTPA. 2

Step 4: Advanced Imaging When Indicated

• Bedside lung ultrasound can detect radio-occult pulmonary lesions with 94.7% sensitivity and 96.7% specificity in patients with pleuritic pain and negative chest X-ray. 4
• Ultrasound findings include: absence of pleural sliding, focal alveolar-interstitial syndrome, peripheral alveolar consolidation, or pleural disruption. 4

Step 5: Cardiac-Specific Evaluation if Indicated

• If myopericarditis suspected: transthoracic echocardiography to assess for pericardial effusion, wall motion abnormalities, or restrictive physiology. 2
• CMR with gadolinium contrast is effective to distinguish myopericarditis from other causes when diagnostic uncertainty exists. 2

Critical Pitfalls to Avoid

• Never assume reproducible chest wall tenderness excludes serious pathology—pleurisy itself can cause chest wall tenderness through spinal reflex mechanisms. 5, 3
• Do not delay transfer from office settings for troponin testing—patients with suspected ACS should be transported urgently to ED by EMS. 2
• Sharp, pleuritic pain does NOT exclude cardiac ischemia. 3
• Nitroglycerin response should never be used as a diagnostic criterion. 3
• Serial ECGs should be performed if initial ECG is nondiagnostic and clinical suspicion remains high. 2

Disposition Based on Findings

• If any concern for ACS, PE, pneumothorax, or aortic dissection: activate 9-1-1 for immediate transport to ED by EMS. 2, 3
• If cardiac and pulmonary workup negative and costochondritis confirmed: treat with NSAIDs. 1, 3
• If viral pleurisy diagnosed: NSAIDs for pain management. 1
• If pericarditis confirmed: anti-inflammatory medications and cardiology consultation. 3