What is the differential diagnosis and management for a patient presenting with chest and back muscle pain?

Differential Diagnosis for Muscle Pain in Chest and Back

Immediate Life-Threatening Conditions to Exclude First

Before attributing chest and back pain to musculoskeletal causes, you must systematically exclude life-threatening conditions through focused examination and ECG within 10 minutes of presentation. 1

Cardiac Causes

• Acute Coronary Syndrome: Presents with retrosternal pressure building gradually over minutes, radiating to left arm/jaw/neck, associated with diaphoresis, dyspnea, or nausea—examination may be completely normal in uncomplicated cases 1, 2
• Pericarditis: Sharp, pleuritic chest pain worsening when supine and improving when leaning forward, with friction rub on examination and fever 1, 2
• Myocarditis: Chest pain with fever, signs of heart failure, and S3 gallop 1

Vascular Causes

• Aortic Dissection: Sudden-onset "ripping" or "tearing" chest or back pain, with pulse differentials between extremities (present in only 30% of patients), blood pressure differentials >20 mmHg, or new aortic regurgitation murmur 1, 2
• Pulmonary Embolism: Acute dyspnea with pleuritic chest pain, tachycardia present in >90% of patients, and tachypnea 1, 2

Other Life-Threatening Causes

• Esophageal Rupture: History of emesis, subcutaneous emphysema, pneumothorax (20% of patients), unilateral decreased or absent breath sounds 1
• Pneumothorax: Dyspnea and pain on inspiration with unilateral absence of breath sounds 1

Musculoskeletal Causes (Diagnosis of Exclusion)

Musculoskeletal chest and back pain can only be diagnosed after excluding life-threatening conditions through appropriate history, examination, and ECG. 1

Common Musculoskeletal Diagnoses

• Costochondritis/Tietze Syndrome: Tenderness of costochondral joints on palpation, pain reproducible with chest wall pressure 1, 2
• Myofascial Pain: Pain localized to a very limited area, affected by palpation, breathing, turning, twisting, or bending 2, 3, 4
• Intercostal Muscle Strain: Pain reproducible with specific postures or physical activities, worsened by movement 3, 4

Key Diagnostic Features Suggesting Musculoskeletal Origin

• Pain reproducible by palpation over the affected structure 1, 3, 4
• Pain triggered by specific postures or physical activities 3, 4
• Sharp pain increasing with inspiration, turning, or twisting 2, 3
• Pain localized to a very small area rather than diffuse 2
• Fleeting pain lasting only seconds (unlikely to be cardiac) 1

Critical Pitfalls to Avoid

Never use nitroglycerin response as a diagnostic criterion—esophageal spasm and other non-cardiac conditions also respond to nitroglycerin. 1, 2, 5

Do not dismiss chest pain in women, elderly patients (≥75 years), or patients with diabetes, as they frequently present with atypical symptoms including sharp or positional pain. 1, 2, 5

Pain reproducible by palpation does not definitively exclude cardiac ischemia—patients with ACS can have concurrent musculoskeletal tenderness. 1, 3

Mandatory Initial Evaluation

History Elements

• Exact onset (gradual over minutes vs. sudden), duration, quality (pressure/squeezing vs. sharp/stabbing), and severity 1
• Radiation pattern (left arm/jaw/neck suggests cardiac; dermatomal suggests herpes zoster) 1
• Precipitating factors (exertion/emotional stress suggests cardiac; specific movements suggest musculoskeletal) 1, 3
• Associated symptoms (diaphoresis, dyspnea, nausea suggest cardiac; fever suggests infection/inflammation) 1

Physical Examination

• Focused cardiovascular examination for murmurs, friction rub, S3, pulse differentials, and blood pressure differentials 1
• Palpation of costochondral joints and chest wall to reproduce pain 1, 3
• Assessment for subcutaneous emphysema, unilateral breath sounds, and percussion abnormalities 1

Immediate Testing

• ECG within 10 minutes to evaluate for ST-segment elevation, new Q waves, or T-wave inversions 1
• Cardiac troponin measurement if any suspicion of ACS exists 1
• Chest radiograph to evaluate for pneumothorax, pneumonia, or widened mediastinum 1

Management of Confirmed Musculoskeletal Pain

Only after excluding life-threatening conditions can you proceed with musculoskeletal-specific treatment. 3, 4

Treatment Approach

• NSAIDs (ibuprofen) for anti-inflammatory effect—monitor for GI bleeding and cardiovascular risks with prolonged use 6, 3, 4
• Muscle relaxants (cyclobenzaprine 5-10 mg three times daily) for muscle spasm—avoid with MAO inhibitors and monitor for serotonin syndrome 7, 3
• Manual therapy and physical therapy including transcutaneous electrical stimulation and stabilization exercises 3, 4
• Local anesthetic injection at tender points for both diagnostic confirmation and therapeutic benefit 3, 4

Red Flags Requiring Immediate Referral

• Age ≥75 years with accompanying dyspnea, syncope, acute delirium, or unexplained fall 1, 5
• Any ECG abnormalities suggestive of ischemia 1
• Elevated cardiac troponin levels 1
• Pulse differentials, blood pressure differentials >20 mmHg, or new murmurs 1