What is the recommended approach for managing referred pain?

Managing Referred Pain

Referred pain should be managed by treating the underlying source of pain while providing symptomatic relief through a stepwise analgesic approach, starting with non-opioid analgesics for mild pain, adding weak opioids for moderate pain, and escalating to strong opioids for severe pain, combined with interventional procedures when the pain source is well-localized and amenable to nerve blocks. 1, 2

Understanding Referred Pain Patterns

Referred pain occurs when pain is perceived at a location distant from its actual source, requiring identification of the underlying pathology rather than treating only the symptomatic area. 1

• Common referred pain patterns include:
  • Upper abdominal visceral pain (pancreas, liver) referring to the back or shoulder 1
  • Pelvic pain referring to the lower back or legs 1
  • Cardiac pain referring to the left arm or jaw 1

Initial Assessment and Diagnosis

Document the complete pain history including onset, quality, intensity (using 0-10 numerical rating scale), distribution, duration, temporal patterns, and both exacerbating and relieving factors. 1, 2

• Ask specifically: "What is your worst pain in the last 24 hours on a scale of 0-10?" 2
• Perform targeted neurological and musculoskeletal examination to identify the true pain source 2
• Evaluate impact on daily activities, sleep quality, mood, and interpersonal relationships 1, 2
• Identify psychological factors (anxiety, depression, anger) and coping mechanisms that may influence pain perception 1, 2

Pharmacological Management Based on Pain Intensity

Mild Referred Pain (Numerical Rating Scale 1-4)

Start with acetaminophen 650 mg every 4-6 hours (maximum 4000 mg/day) or NSAIDs as first-line therapy. 1, 2

• NSAIDs are superior to placebo for controlling pain in single-dose studies 1
• Monitor baseline blood pressure, renal function (BUN, creatinine), liver function tests, CBC, and fecal occult blood at baseline and every 3 months 1
• Discontinue NSAIDs if liver function tests exceed 3 times the upper limit of normal 1
• Consider COX-2 selective inhibitors for patients at high risk of gastrointestinal bleeding, though they carry cardiovascular risks and do not reduce renal toxicity 1
• If two NSAIDs fail sequentially, switch to an alternative analgesic approach rather than trying additional NSAIDs 1

Moderate Referred Pain (Numerical Rating Scale 5-7)

Add weak opioids (codeine, tramadol) to non-opioid analgesics, or initiate low-dose strong opioids. 1, 2, 3

• Tramadol 200-400 mg/day provides effective analgesia but carries higher risk of nausea, vomiting, vertigo, and asthenia compared to other options 1
• Combination products containing acetaminophen plus weak opioids are traditional second-step options, though evidence for superiority over non-opioids alone is limited 1

Severe Referred Pain (Numerical Rating Scale 8-10)

Initiate strong opioids such as morphine (preferred first-line), hydromorphone, oxycodone, or fentanyl, with oral administration preferred when possible. 1, 2, 3

• Provide around-the-clock dosing for persistent pain rather than "as needed" administration 2, 3
• Include breakthrough doses (10-15% of total daily dose) for transient pain exacerbations 2, 3
• Titrate doses rapidly to achieve effective pain control 2, 3
• Adjust baseline opioid regimen if more than four breakthrough doses are needed daily 2, 3

Interventional Approaches for Referred Pain

Consider interventional procedures when referred pain originates from well-localized sources amenable to nerve blocks or when systemic analgesics fail to provide adequate relief without intolerable side effects. 1

Specific Interventional Options by Location:

• Upper abdominal visceral pain: Celiac plexus block or thoracic splanchnicectomy 1
• Midline pelvic pain: Superior hypogastric plexus block 1
• Rectal pain: Intrathecal neurolysis, midline myelotomy, or superior hypogastric plexus block 1
• Thoracic wall pain: Epidural neurolysis or intercostal neurolysis 1
• Upper extremity pain: Brachial plexus neurolysis 1
• Unilateral pain syndromes: Cordotomy when other interventions are inappropriate 1

Additional Interventional Procedures:

• Regional infusions via infusion pump 1
• Percutaneous vertebroplasty/kyphoplasty for vertebral pain 1
• Radiofrequency ablation for bone lesions 1
• Neurostimulation procedures for neuropathic symptoms 1

Contraindications to interventional procedures include infection, coagulopathy, very short or lengthy life expectancy, distorted anatomy, patient unwillingness, and medications increasing bleeding risk (such as bevacizumab). 1

Adjuvant Medications for Neuropathic Components

When referred pain has neuropathic characteristics, add anticonvulsants (gabapentin, pregabalin), antidepressants (tricyclics, SNRIs), or corticosteroids. 2, 3

Monitoring and Follow-up

Evaluate pain at every clinical contact or at least daily for hospitalized patients using standardized self-reporting tools. 2, 3

• Reassess both pain intensity and analgesic side effects regularly 2
• Review and adjust the analgesic regimen if side effects persist or pain remains uncontrolled 2
• Provide written pain management plans including all prescribed medications 2

Common Pitfalls to Avoid

Do not treat only the referred pain location without identifying and addressing the underlying source. 1

• Avoid underestimating pain severity in patients with cognitive impairment; observe behavioral indicators such as facial expressions, body movements, and vocalizations 2
• Do not continue ineffective treatments indefinitely; if two NSAIDs fail sequentially, switch therapeutic approaches 1
• Avoid combining acetaminophen with opioid-acetaminophen combination products to prevent hepatotoxicity from excessive acetaminophen dosing 1
• Do not prescribe opioids "as needed" for persistent referred pain; use scheduled dosing with breakthrough doses available 2, 3
• Recognize that many patients have multiple concurrent pain types requiring individualized combination therapy 3