Pain

The Pain Experience

based on : https://www.racgp.org.au/clinical-resources/clinical-guidelines/key-racgp-guidelines/view-all-racgp-guidelines/drugs-of-dependence/part-c2/approach-to-pain-management

Definition and Types of Pain:

• Pain Definition: Pain is described by the International Association for the Study of Pain (IASP) as an unpleasant sensory and emotional experience linked to actual or potential tissue damage.
• Acute Pain: Results from actual or threatened tissue damage and activates nociceptors.
• Chronic Pain: Persistent or recurrent pain lasting typically three months or more, including conditions like fibromyalgia, non-specific back pain, osteoarthritis, headaches, chronic cancer pain, and chronic post-surgical pain.

Biopsychosocial Model of Pain:

• The understanding of pain has evolved from a simple biomedical model to a comprehensive biopsychosocial approach, recognizing that pain is influenced by biomedical, psychological, and social factors. In chronic non-cancer pain (CNCP), social and psychological factors often dominate.

Individual Pain Experience:

• Pain and disability levels vary greatly among individuals with similar injuries.
• Responses to pain relief methods also vary individually.
• Communicating the pain experience can be challenging for patients, leading to frustration and distress.

Management of Pain:

• Effective pain management requires considering patients’ beliefs, needs, and expectations.
• Pain affects many aspects of a patient’s life, including daily activities, leisure, and sleep.
• Severe pain often correlates with a lower quality of life, with pain reduction being a primary goal for many patients.
• Building a collaborative partnership between patient and GP is crucial, emphasizing empathy and understanding.

Patient-Doctor Relationship:

• Patients need to feel their pain is understood and validated.
• It’s important to show interest in the patient as a person, not just their symptoms.
• Patients’ opinions on pain management should be valued.
• Optimism about improving their condition is essential.

Role of the GP:

• Patients may struggle with the involvement of multiple healthcare professionals, leading to confusion.
• Having a primary care doctor, ideally a GP, who knows the patient’s medical history and can coordinate care is important for effective management of chronic pain.

Placebo Effects:

• Placebo: A substance or procedure without inherent ability to produce an expected effect, but can have similar profiles to non-placebos.
• Placebo Response: Therapeutic response to a known placebo.
• Placebo Effect: Part of the therapeutic response not attributable to active ingredients, influenced by sociocultural treatment context.

Determinants of Placebo Effects:

• Influenced by doctor-patient relationship, expectancy, classical conditioning, and social/observational learning.
• Variability exists in degree and duration of placebo effects.

Pathways for Placebo Effects:

• Higher placebo analgesia when induced via suggestion combined with conditioning.
• Mediated by endogenous opioids, cholecystokinin, endogenous cannabinoid systems, and dopamine release.

Ethical Considerations and Practical Use:

• Placebos should not be administered deceptively.
• Using placebo effects to augment active treatments is becoming less contentious.
• More clinical research is needed to determine the practical value of placebos.
• Practitioners should consider how they deliver information to harness placebo effects and optimize treatment outcomes.

Pathophysiology-based Classification

Nociceptive Pain

• Definition: Arises from actual or threatened damage to non-neural tissue.
• Function: Guards against tissue injury and supports healing.
• Subtypes:
  • Visceral Pain: Stimulation of nociceptors within the viscera.
  • Somatic Pain: Stimulation of nociceptors in the musculoskeletal system.
• Duration: Typically lasts with continual noxious stimuli and resolves after tissue injury resolution.
• Chronic Nociceptive Pain: May occur in diseases like rheumatoid arthritis.

Neuropathic Pain

• Definition: Caused by a lesion or disease of the somatosensory nervous system.
• Causes: Mechanical trauma, metabolic diseases, neurotoxic chemicals, infection, tumor invasion.
• Diagnostic Criteria:
  • Appropriate history.
  • Signs of neurological deficit.
  • Diagnostic interventions.
  • Confirmation of underlying cause.
• Chronic Neuropathic Pain: Heterogeneous group of conditions.
• Co-occurrence: Nociceptive and neuropathic pain may coexist.
• Treatment: Less than ideal, with fewer than 50% achieving satisfactory relief.

Nociplastic Pain

• Definition: Pain from altered nociceptive processing without clear evidence of tissue damage or somatosensory system disease.
• Conditions: Fibromyalgia, complex regional pain syndrome (CRPS), non-specific chronic low back pain, functional visceral pain disorders.
• Mechanism: Altered function of nociceptive pathways.

Psychophysiological Approach

• Examined the influence of mental events on physical changes producing pain.
• General arousal models suggested prolonged ANS arousal and muscular contractions generate and perpetuate pain.
• Treatments like EMG, biofeedback, and relaxation techniques aim to reduce muscular tension and ANS arousal.

Current Theoretical Models

• Many acute musculoskeletal injuries do not resolve quickly, leading to chronic pain.
• Early intervention improves outcomes.
• The “Yellow Flags” concept screens for risk factors in developing chronic pain.
• Pincus et al. proposed an Integrated Biopsychosocial Risk-for-Disability Model, combining cognitive and behavioral factors.

Pain-Related Fear and Disability

• Acute pain associated with anxiety responses; chronic pain linked to vegetative signs of depressive disorders.
• Fear of pain can be more disabling than pain itself.
• Pain-related fear predicts performance and disability levels, with avoidance behaviors leading to physical deconditioning and chronicity.
• Chronic pain may result in physical deconditioning, lowering pain thresholds, and increasing the likelihood of avoiding activities.

Catastrophic Thinking and Pain-Related Fear

• Catastrophic thinking involves exaggerated orientation towards pain stimuli.
• Negative appraisals about pain can lead to persistent pain.
• Pain-related fear interferes with cognitive functions, leading to hyper-vigilance and difficulty shifting attention away from pain-related information.

Pain History Taking

General Assessment and Pain-Specific History

• Thorough History
  • Chronic pain evaluation is crucial.
  • Pain assessment as the “fifth vital sign.”
  • Familiarity with the patient and input from families/support systems.
• Pain Characteristics
  • Location
  • Radiation
  • Intensity
  • Quality (sharp, dull, squeezing, throbbing, colicky)
  • Temporal aspects (duration, onset, changes since onset)
  • Constancy or intermittency
  • Breakthrough pain characteristics
  • Exacerbating/triggering factors
  • Relieving factors
  • Associated symptoms:
    • Restricted range of motion, stiffness, swelling
    • Muscle aches, cramps, spasms
    • Color or temperature changes
    • Changes in sweating, skin, hair, or nail growth
    • Changes in muscle strength or sensation (dysesthesias/itching, numbness)

Psychosocial History Taking and Assessment

Pain Impact on Function and Quality of Life

• Social and Recreational Activities Interference with hobbies, socializing, travel
• Mood, Affect, and Anxiety Impact on energy, mood, personality
• Relationships Effect on family, friends, colleagues
• Occupation Impact on work responsibilities, hours, or cessation of work
• Sleep Interference with sleep
• Exercise Interference with exercise activities
• Activities of Daily Living (ADLs) and Instrumental Activities of Daily Living (IADLs)
  • Bathing, dressing, toileting, feeding
  • Shopping, using transportation, meal preparation, housework, managing finances and medications

Social Assessment

• Influences Family, work, life events, housing, sleep, activity, and nutrition
• Social Participation
  • Participation in pleasurable activities (hobbies, movies, concerts, socializing, travel)
  • Frequency of pain interference over the past week
• Mood and Relationships
  • Pain’s impact on energy, mood, personality, and tearfulness
  • Effect on relationships with family, significant others, friends, colleagues
• Occupational Impact
  • Modification of work responsibilities and/or hours due to pain
  • Time since last worked and reasons for stopping work
• Sleep and Exercise
  • Pain interference with sleep and exercise
  • Frequency of exercise and pain interference over the past week
• Isolation and Pain-Depression Cycle
  • Social interactions, occupational performance, self-care
  • Use of pain for sympathy, protection, benefits, or medico-legal compensation

Psychological Assessment

• Behavioral Assessment
  • Explore patient’s personal and family history and support system
  • Inquire about psychological disorders and substance abuse history
  • Patient’s beliefs about pain and healthcare experiences
• Patient Perceptions
  • Causes of persistent pain
  • Adequacy of diagnostic work-up
  • Expectations for specific treatments
  • Goals for treatment (pain relief and functional improvement)
  • Involvement in treatment planning and execution
• Mood State, Beliefs, Coping Skills
  • Explore patient’s mood, beliefs, coping skills, behaviors, and responses contributing to pain experience
  • Identify obstacles to recovery and treatment outcome
• Psychological Factors
  • Use screening tools for mood and anxiety disorders
  • Anxiety as a predictive factor for postoperative pain severity
  • Association between chronic postsurgical pain (CPSP) and depression
  • Relevant beliefs about diagnosis, prognosis, and treatment expectations
  • Fear of pain contributing to avoidance responses and potential disability
  • Negative, ruminative, and helpless thinking styles (e.g., catastrophic thinking)

Physical Examination

• Assessment for Signs of Tissue Damage/Injury or Disease
  • Signs of nociceptive and/or neuropathic mechanisms of pain (e.g., tissue deformity, inflammation, neural disease or damage)
• Evaluation of Referred Pain Sources
  • Including visceral sources
• Observations
  • Hypervigilance or guarding with particular movements
  • Compensatory postures and movements
  • Evidence of allodynia, hypoalgesia, hyperalgesia
• Provisional Diagnosis
  • Establish diagnosis for pain and biomedical mechanism involved
  • Analyze disability level of the patient

Measurement of Pain and Functional Impact

• Pain Scoring Systems
  • Verbal numerical rating scales for simplicity and consistency
  • PEG scale for chronic musculoskeletal pain in general practice
  • PEG scale scores (out of 30) as reference points for patient’s overall wellbeing
  • Use of pain scores to compare patient assessments over time

Risk Assessment for Opioid Prescription

• Careful Prescription of Opioids: Opioids are effective analgesics but require careful prescribing to limit risks such as inappropriate use and diversion.
• High-Risk Groups for Problematic Opioid Usage:
  • Younger Patients: Substance use issues generally commence before 35 years of age.
  • Patients Without Definite Patho-Anatomic Diagnosis: Lack of clear diagnosis increases misuse risk.
  • Patients with Active Substance Use Problems: Includes those in contact with individuals with substance use problems.
  • Patients with Active Psychiatric Problems: Increases risk of misuse and side effects.
  • Patients Using Benzodiazepines: Concomitant use substantially increases risks of cognitive impairment, sedation, and respiratory depression.
• Comprehensive Assessment:
  • Address the risk of opioid misuse through thorough patient evaluation.
  • Screening for opioid risk is recommended but lacks strong evidence of effectiveness.
  • Treatment agreements and urine testing are recommended but have not significantly reduced opioid prescribing, misuse, or overdose rates.
• Patients with History of Substance Use Disorder (SUD):
  • Higher risk of harm from opioids.
  • Check state-based prescription monitoring systems.
  • Generally, avoid offering opioids in general practice settings; refer to specialist services if pain control is unachievable by other means.
• Urine Drug Screening (UDS):
  • May reveal substances unknown to the practitioner.
  • Not all substances are routinely tested (e.g., specific request needed for oxycodone testing).
  • If unexpected drugs (illicit or legal) are found, refer the patient for specialist assessment and management.
  • Contact local pathology provider for necessary testing.