What could be causing unilateral muscle pain in my arm, shoulder, back, neck, and chest that worsens with lifting?

Unilateral Muscle Pain Affecting Arm, Shoulder, Back, Neck, and Chest with Lifting

You must immediately seek emergency medical evaluation to rule out cardiac ischemia, as chest pain with radiation to the arm, shoulder, neck, and back—especially when worsened by exertion—can represent acute coronary syndrome, which is a life-threatening condition requiring urgent intervention. 1

Immediate Red Flag Assessment

Cardiac evaluation takes absolute priority. The 2021 AHA/ACC guidelines emphasize that chest pain should be described as "cardiac, possibly cardiac, or noncardiac" rather than dismissed as atypical, because the latter term can be misinterpreted as benign when it may represent myocardial ischemia 1. Your symptoms include multiple features concerning for cardiac origin:

• Pain location: Chest discomfort radiating to shoulder, arm, neck, and back is characteristic of ischemic cardiac pain 1
• Exertional component: Pain that worsens with lifting (physical exertion) is a classic feature of angina pectoris 1
• Radiation pattern: Ischemic pain commonly radiates to the shoulder, arm, neck, back, or jaw 1

Mandatory Immediate Actions

• Obtain ECG and cardiac biomarkers immediately to exclude acute coronary syndrome before attributing symptoms to musculoskeletal causes 2
• Document vital signs including blood pressure and heart rate 2
• Assess cardiac risk factors including age, diabetes, hypertension, smoking, and family history 1

Do not assume this is "muscle tension" or "muscle spasm" without ruling out cardiac pathology first. 3

If Cardiac Etiology is Excluded: Musculoskeletal Differential Diagnosis

Once life-threatening cardiac causes are definitively ruled out, the unilateral distribution spanning multiple regions suggests either:

Primary Consideration: Cervical Radiculopathy

Cervical spine pathology with nerve root compression is the most likely musculoskeletal cause of unilateral pain radiating from neck through shoulder, back, arm, and chest 3, 4. This diagnosis is supported by:

• Radiation pattern: Pain following a dermatomal distribution from neck into shoulder and arm is pathognomonic for cervical radiculopathy 3
• Exertional worsening: Lifting increases mechanical stress on compressed nerve roots 5
• Unilateral presentation: Nerve root compression typically affects one side 3

Specific Clinical Features to Document

• Neurological symptoms: Numbness, tingling, or weakness in specific fingers (C5-C8 distribution) 3, 4
• Dermatomal pattern: C5 affects lateral arm; C6 affects thumb/index finger; C7 affects middle finger; C8 affects ring/little fingers 3
• Neck movements: Pain worsening with neck extension or rotation toward the affected side 5
• Spurling's test: Axial compression with neck extension reproducing radicular symptoms 3

Diagnostic Imaging Algorithm for Suspected Radiculopathy

1. Cervical spine radiographs first: Assess alignment, degenerative changes, and gross structural abnormalities 3, 4
2. MRI cervical spine without contrast: Definitive study to visualize disc herniations, osteophytes, foraminal stenosis, and nerve root compression 3, 4
3. Electrodiagnostic testing: If imaging is negative or equivocal, EMG/NCS has >80% sensitivity and 95% specificity for confirming nerve compression 3

Secondary Consideration: Rotator Cuff Pathology

In patients over 35-40 years, rotator cuff disease is a predominant cause of shoulder pain 3, 4. However, this diagnosis is less likely given your symptom distribution because:

• Rotator cuff tears do not cause chest, back, or neck pain 4
• Rotator cuff pathology does not produce numbness in specific digits 4
• Anterior shoulder pain specifically suggests rotator cuff or biceps tendon involvement, not diffuse unilateral pain 3

If Rotator Cuff is Suspected

• Physical examination maneuvers: Empty can test, external rotation resistance testing, and impingement signs 2
• Initial imaging: Standard shoulder radiographs with minimum three views (AP internal/external rotation, axillary or scapular-Y view) 1, 2
• Advanced imaging: MRI shoulder without contrast or ultrasound (if local expertise available) to evaluate soft tissue injuries 1

Most rotator cuff pathology can be managed conservatively initially with rehabilitation and pain management, without requiring immediate surgery 3, 4

Tertiary Consideration: Musculoskeletal Chest Wall Pain

If both cardiac and neurological causes are excluded, consider chest wall structures 1:

• Costochondritis: Inflammation of rib cartilages causing chest pain 1
• Intercostal myofascial injury: Trauma to connective tissues between ribs 1
• Rib injury: Direct trauma to ribs from lifting mechanism 1

However, these diagnoses would not explain the concurrent neck, shoulder, back, and arm involvement 1.

Management Algorithm After Diagnosis

If Cervical Radiculopathy Confirmed

• Conservative management initially: Restricted activity, analgesics, anti-inflammatories, and cervical collar application 5
• Neuropathic pain medication: Pregabalin 300-600 mg daily in divided doses, gabapentin, or duloxetine 3
• Rehabilitation referral: Once acute symptoms subside, gradual resumption of activities 5
• Urgent surgical evaluation: Required if progressive motor deficits or massive nerve compression develops 4

If Rotator Cuff Pathology Confirmed

• Rehabilitation specialist referral for comprehensive conservative management 3
• Expedited surgical timeline: Only if massive traumatic rotator cuff tear is identified 1

Pain Control Strategy (General)

• First-line: Acetaminophen 650-1000 mg every 6 hours (maximum 4 grams daily) 2
• Avoid prolonged NSAIDs: Due to gastrointestinal, renal, and cardiovascular risks 2

Critical Pitfalls to Avoid

1. Never dismiss chest pain as "atypical" or "musculoskeletal" without cardiac workup 1, 3
2. Do not delay imaging if red flags present: Progressive weakness, bowel/bladder dysfunction, or severe unrelenting pain 3
3. Recognize that weight lifting can cause both cervical radiculopathy and peripheral nerve injuries through direct trauma, compression, or excessive stretching 5, 6
4. Understand that delayed-onset muscle soreness (DOMS) from exercise typically occurs 1-5 days post-exercise and is bilateral, not unilateral with neurological features 7

Seek immediate emergency department evaluation for definitive cardiac assessment before pursuing any other diagnostic pathway. 1, 2