Types of Pain

• Chronic Pain:

  • Lasts several months or longer

  • Often associated with a disease

  • Can be treatment resistant

  • More common in females and the elderly

  • Most common type is musculoskeletal pain (muscles, bones, ligaments)

• Acute Pain:

  • Comes on suddenly and resolves quickly

  • Usually diagnosed and treated based on specific location

  • Results from disease, inflammation, or tissue injury

  • Often a symptom of a recent event, such as an injury

Factors Affecting Pain

Several factors can influence the experience of pain:

• Learning:

  • E.g. Jamner and Turskey (1987) found that exposure to words associated with pain in migraine sufferers increased anxiety and their sense of pain.

• Anxiety:

  • McGowan et al. (1988) found a correlation between anxiety and the strength of pelvic pain in women.

• Gender:

  • Morin et al. (2000) showed that women often experience more intense post-surgical pain than men, whereas men are more affected by mild pain lasting several days.

• Cognition:

  • The perception of control and ability to manage pain affects pain sensation, forming the basis for cognitive therapies.

Phantom Limb Pain (PLP)

• Common among amputees, causing sensations of pain in missing limbs.

• Melzack (1992) - Characteristics of PLP:

  • Phantom limb feels real.

  • Can become stuck in awkward positions.

  • Patients perceive artificial limbs as part of their body.

Example Study: MacLachlan et al. (2004)

• Sample: 32-year-old male, Alan, underwent leg amputation at the hip.

• Procedure:

  • Experienced PLP two days post-surgery; described pain as "pins and needles" at first, which escalated throughout the day.

  • Used mirror therapy to alleviate pain.

• Treatment:

  • Mirror treatment began after unsuccessful pain medication and TENS.

  • Engaged in exercises using a mirror to perceive movement without pain.

  • By the end of the three weeks, participation was independent and frequent.

• Results:

  • Initial phantom pain reported as 5-9 and stump pain as 0-2.

  • End assessment indicated phantom pain rated as 0 and stump pain as 1.

  • Sense of control over PLP increased from 0-3% to 25-30%.

  • The phantom limb felt shorter but could be ‘straightened out’.

• Conclusion:

  • Demonstrated mirror therapy as an effective treatment for PLP.

Evaluation of the MacLachlan et al. Study:

• Strengths:

  • Case study method provided detailed, rich qualitative data.

  • First reported case of successful mirror therapy for PLP.

• Weaknesses:

  • Low generalizability due to one participant.

  • Low reliability in the findings.

Theories of Pain

Specificity Theory (Von Frey, 1895)

• Proposes a separate sensory system for processing pain.

• Specialized pain receptors respond to stimuli and send signals to the brain.

• Provides a straightforward explanation for pain perception.

Evaluation:

• Strengths:

  • Clarity in explaining pain perception.

• Weaknesses:

  • Reductionist; overlooks psychological and cognitive factors.

  • New research indicates pain involves more than specific receptors.

Gate Control Theory (Melzack & Wall, 1965)

• Suggests that non-painful input can affect pain perception by closing gates in the spinal cord, preventing pain signals from reaching the brain.

• Increased activity in large nerve fibers (for touch and pressure) versus small nerve fibers (for pain) can reduce pain sensation.

Evaluation:

• Strengths:

  • Supported by animal studies showing brain stimulation leading to numbness.

• Weaknesses:

  • Lacks physical evidence for the existence of a 'gate'.

  • Treats physical and psychological processes as separate.

Measuring Pain

Subjective Measures: Clinical Interview

• Consists of gathering medical history and performing clinical interviews using open-ended questions.

• Uses acronym ‘ACT-UP’ to guide inquiries regarding activities, coping, thoughts, emotions, and reactions from others.

Evaluation:

• Strengths:

  • Deep understanding of patient experience; qualitative data.

• Weaknesses:

  • Potential inaccuracies in self-reporting due to downplaying/misinterpreting pain.

McGill Pain Questionnaire (MPQ)

• Evaluates intensity and quality of pain by categorizing descriptors.

• Ranges from 0 (no pain) to 78 (severe pain).

Evaluation:

• Strengths:

  • Detects changes in pain over time; easier statistical analysis.

• Weaknesses:

  • Closed questions limit full representation; no qualitative data.

Visual Analogue Scale (VAS)

• Allows patients to indicate pain on a continuum from no pain to extreme pain.

• Total distance from endpoint represents pain level, converted to numerical value between 0-100.

Evaluation:

• Strengths:

  • Quick and sensitive to small changes.

• Weaknesses:

  • Lack of qualitative data limits comprehensiveness.

UAB Pain Behaviour Scale

• Observer records behaviors associated with pain severity, frequency, and intensity.

Evaluation:

• Strengths:

  • Provides observable data about pain behaviors.

• Weaknesses:

  • Observer bias can affect interpretation; may not reflect subjective experience.