Referred Pain: Why You Feel Pain Far From Its Source

Referred pain occurs when pain is perceived at a site distant from the actual injury or pathology. This happens because visceral and somatic sensory neurons converge on the same spinal cord segments, causing the brain to misinterpret the origin.

Classic Examples

• Heart ischemia → Left shoulder, arm, jaw, or epigastrium
• Gallbladder inflammation → Right shoulder tip (phrenic nerve irritation)
• Diaphragmatic irritation → Shoulder (Kehr's sign: left shoulder from splenic rupture)
• Kidney stone → Flank to groin
• Lung apex tumor (Pancoast) → Medial arm/ulnar distribution

Common Underlying Conditions

• Cardiac: MI, pericarditis
• Pulmonary: Pneumonia, pleurisy, PE
• GI: Ulcer, pancreatitis, biliary colic
• Musculoskeletal: Facet joint, myofascial trigger points
• Neurologic: Radiculopathy, nerve compression

Clinical Importance

Recognizing referral patterns prevents misdiagnosis (e.g., treating "shoulder pain" that's actually an MI). Always consider visceral sources for unexplained somatic pain. A thorough history, exam, and targeted workup (ECG, imaging, labs) are essential.