What is chronic pain disorder and how is it managed?

What is Chronic Pain Disorder and Its Management

Chronic pain is defined as pain persisting or recurring for more than 3 months beyond expected healing time, and should be managed with a multimodal approach prioritizing physical activity as the foundation, combined with psychological interventions and targeted pharmacotherapy based on pain mechanism (nociceptive, neuropathic, or centralized). 1, 2

Definition and Classification

Chronic pain represents a distinct disease entity rather than merely a symptom, characterized by pain extending beyond expected tissue healing periods (>3 months). 3, 1 The condition encompasses:

• Chronic primary pain: Pain as the primary disease itself (e.g., fibromyalgia, nonspecific low back pain) 1
• Chronic secondary pain: Pain secondary to underlying conditions including cancer-related, neuropathic, visceral, posttraumatic/postsurgical, headache/orofacial, and musculoskeletal pain 1

The term "persistent pain" is preferred over "chronic pain" as the latter suggests depression and futility, potentially leading to inadequate reassessment of underlying causes. 4

Pain Mechanisms and Assessment

Three pathophysiologic pain types must be identified to guide treatment:

• Nociceptive pain (e.g., osteoarthritis): Tissue damage-related 3
• Neuropathic pain: Nerve injury or dysfunction 3
• Centralized pain/central sensitization: Amplified pain processing (e.g., fibromyalgia) 3

Assessment must adopt a biopsychosocial lens rather than purely biomedical, evaluating the whole patient including comorbidities, cognitive/emotional/behavioral characteristics, social environment, and functional impairment. 3 Risk stratification should identify psychosocial factors (mood disturbances, sleep problems, passive coping strategies) that predict pain persistence and disability. 4, 3

Management Algorithm

Foundation: Non-Pharmacologic Interventions

Physical activity is the primary recommended treatment for chronic osteoarthritis and low back pain with demonstrated long-term benefit, though evidence is unclear for neuropathic pain. 2

• Physical/restorative therapy: Effective for low back pain relief for 2-18 months and should be used as part of multimodal strategy 5
• Psychological interventions: Cognitive behavioral therapy, biofeedback, and relaxation training provide back pain relief for 4 weeks to 2 years 5; mindfulness-based stress reduction is also recommended 2
• Self-management support: Proactive education with written information and peer support access, though high-quality trial evidence is limited 4

Pharmacologic Management by Pain Type

For Nociceptive Pain (e.g., Osteoarthritis):

• First-line: Acetaminophen and NSAIDs 3, 2

For Neuropathic Pain:

• Anticonvulsants (α-2-delta calcium-channel antagonists, sodium-channel antagonists, membrane-stabilizing drugs) as part of multimodal strategy 5
• Tricyclic antidepressants (amitriptyline, nortriptyline, desipramine, imipramine) 5, 3
• Serotonin-norepinephrine reuptake inhibitors (duloxetine, venlafaxine, desvenlafaxine, milnacipran) 5, 3
• Selective serotonin reuptake inhibitors specifically for diabetic neuropathy 5
• Topical agents (capsaicin, lidocaine, ketamine) for peripheral neuropathic pain 5

For Centralized Pain/Central Sensitization:

• Tricyclic compounds 3
• Serotonin-norepinephrine reuptake inhibitors 3
• α2δ ligands 3

Adjunctive Considerations:

• Extended-release oral opioids for neuropathic or back pain in selected patients only 5
• NMDA receptor antagonists for selected neuropathic pain patients 5

Treatments Where Harms Outweigh Benefits

Opioids and cannabinoids should be avoided as harms likely outweigh benefits for chronic pain conditions. 2

• Benzodiazepines: Consultants and members disagree on use; minimal evidence supports efficacy 5
• Skeletal muscle relaxants: Insufficient evidence for pain relief 5

Critical Implementation Points

A monitoring strategy for side effects, adverse effects, and compliance must be established before prescribing any long-term pharmacologic therapy. 5

Pain management plans should be reviewed within 6 months, with consideration for treatment changes or specialist referral if no improvement is observed. 4 The approach requires ongoing assessment and adjustment based on patient response, recognizing that chronic pain affects 86% of patients with certain conditions and significantly impacts daily functioning. 6

Common pitfalls include: failing to address psychosocial factors that perpetuate pain 4, adopting purely biomedical perspectives 3, using passive coping strategies associated with higher disability 4, and inadequate patient education about pain persistence mechanisms 4.