Why do older adults with a history of cardiovascular disease experience referred pain to the jaw, shoulder, neck, and epigastric areas in angina?

Neuroanatomical Basis of Referred Pain in Angina

Referred pain to the jaw, shoulder, neck, and epigastric areas during angina occurs due to convergence of visceral cardiac afferent nerves and somatic sensory nerves at shared spinal cord segments (C3-T5) and the trigeminal nucleus in the brainstem, causing the brain to misinterpret cardiac ischemic signals as originating from these somatic structures. 1

Mechanism of Viscerosomatic Convergence

The pathophysiology involves the following neuroanatomical pathway:

• Cardiac afferent fibers carrying ischemic pain signals from the myocardium travel via sympathetic nerves through the middle and inferior cervical ganglia and upper thoracic sympathetic chain (T1-T5 levels), entering the spinal cord at these same segments 1

• Somatic sensory neurons from the jaw (via trigeminal nerve), neck (C3-C4), shoulder (C5), arm (C5-T1), and epigastric region (T5-T9) also synapse at overlapping spinal cord levels and brainstem nuclei 1

• Convergence at the trigeminal nucleus specifically explains jaw and facial pain referral during myocardial ischemia, as visceral cardiac relays and somatic craniofacial sensory inputs merge at this brainstem structure 1

• The central nervous system cannot distinguish between visceral cardiac input and somatic input when both converge on the same second-order neurons in the dorsal horn and brainstem, resulting in the brain interpreting the pain as arising from the somatic distribution 1

Clinical Patterns of Referred Pain

These referred pain patterns are recognized as "anginal equivalents" - symptoms that should be considered equivalent to typical chest discomfort when they have a clear relationship to exertion or stress, or are relieved promptly with nitroglycerin 2, 3:

• Jaw, neck, and ear discomfort may occur as the sole presenting symptom without any chest pain, particularly in older adults and women 2, 4

• Shoulder, arm, and back pain (especially left-sided) represent classic radiation patterns from cardiac ischemia 2, 4

• Epigastric discomfort can mimic gastrointestinal pathology but may be the primary manifestation of myocardial ischemia 2, 4

• Women experience jaw pain significantly more frequently than men during acute coronary syndrome (10% vs 4% in the Global Registry of Acute Coronary Events), and 61.9% of women versus 54.8% of men report pain in the jaw, neck, arms, or between shoulder blades 4

Critical Diagnostic Considerations

The key to recognizing these symptoms as cardiac in origin is their relationship to exertion and relief pattern:

• Symptoms that are reproducibly associated with physical exertion or emotional stress and relieved promptly (less than 5 minutes) with rest and/or sublingual nitroglycerin should be considered anginal equivalents 2, 3

• Common pitfall: Dismissing jaw pain as dental, neck pain as musculoskeletal, or epigastric pain as gastrointestinal without first excluding cardiac causes, especially in women over 50, diabetics, and elderly patients 4

• High-risk populations for atypical presentations include older adults (>75 years), women, and diabetic patients who may have autonomic dysfunction 2, 4

Symptoms NOT Characteristic of Cardiac Ischemia

To avoid misdiagnosis, recognize that the following patterns argue against cardiac origin 2:

• Pleuritic pain (sharp or knifelike pain with respiratory movements or cough)
• Pain localized with one fingertip, particularly over the left ventricular apex
• Pain reproduced by palpation or movement of the chest wall or arms
• Very brief episodes lasting only seconds
• Pain radiating to the lower extremities

Clinical Action Required

Any patient presenting with jaw, neck, shoulder, or epigastric discomfort should receive immediate cardiac evaluation if:

• The discomfort has an exertional component or stress relationship 2, 3
• The patient has cardiovascular risk factors (age >55 in men, >65 in women, diabetes, hypertension, hyperlipidemia, smoking, family history) 2, 4
• The symptoms are new-onset or represent a change from prior patterns 2

Immediate workup includes: 12-lead ECG, cardiac biomarkers (troponin), and placement in a monitored environment with defibrillation capability 4