PSYC 365: Week 8 - Pain

Significance of Pain

1. Produces withdrawal that prevents further injury

2. Serves as basis of learning to avoid injurious objects/situations

3. Sets limits on activity and enforces inactivity and/or rest

Pain Perception

When contact with injurious stimuli occurs, signals follow a particular route

1. Nocioceptors of the afferent (sensory) neurons (PNS) respond to stimuli

2. Generate impulses that travel to the CNS

A-Delta Fibres

Sharp, distinct pain; fast

C-Fibres

Dull, aching pain; slow

Gate Control Theory

States that a gate-like mechanism in the spinal column's dorsal horns

1. Control pain stimulation on the brain

2. Is affected by nerves fibres activity

3. Is opened/closed through central control trigger activity in spinal cord and brain

Posits that Pain Sensations:

1. Can be modified en route to the brain

2. Can be influenced by psychological factors

Neuromatrix Theory

Greater emphasis on brain's role in pain perception -> neurosignature patterns
1. Origins can be innate or sensory

Phantom Limb Pain

Common in those who have undergone amputation
1. Evidence that those born without certain limbs can also experience phantom limb pain

Neurochemical Basis of Pain Inhibition

1. Stimulation of the periaqueductal grey area in rats blocks pain
-Called stimulation-produced analgesia
2.Endogenous opioids regulate pain; complex functioning.
-Beta-endorphin, proenkephalin, and prodynorphin

Acute Pain

Chronic Pain

>6 Months

Chronic Recurrent Pain

Intermittent intense episodes of acute pain followed by relief

Chronic Intractable Benign Pain

Continuous pain that varies in intensity

Chronic Progressive Pain

Continuous pain that gradually intensifies as a persons's condition worsens

Respondent Pain

Pain that occurs in response to noxious stimulation or tissue damage

Operant Pain

Pain that is reinforced by a person's environment

Gender Differences in Pain

1. Women report pain that is more sever, frequent and lengthy than main 2, Perception and response to pain

2. Psychosocial and bio factors

3. Response of health care system

Women & Pain

1. Pain threshold and tolerance lower in women

2. Women report pain more (and more descriptively) and attend to pain more

3. Biology may predispose women to higher pain

4. Physicians may think women dramatize

Cultural Differences

1. Different meanings attaches to pain

2. Stereotypes associated with various cultural experiences

3. Health care attitudes towards pain differ; influences interpretation and treatment of pain symptoms

Measurement of Pain

Psychophysiological Measures: Assess changes in physiological activity from pain

1. Eclectromyograph (EMG)

2. Measures of autonomic activity

3. Electroencephalograph (EEG) --> Detexts evoked potentials

Behavioural Assessment of Pain

Analyzes pain behaviours to see pain's disruption to life
1. In day-to-day activities and clinical setting

Self-Report Measures of Pain

Interviews
Rating Scales: Visual analog scales, box scales, verbal rating scales
Pain questionnaires

Pain Assessment in Infants & Children

Difficult due to language limits

1. Infants: Facial activity convey most information (Neonatal Facial Coding System)

2. Children: Special scales and self-report questionnaires

Pharmacological Control of Pain

1. Peripherally Acting Analgesics - Non-Narcotics

2. Centrally Acting Analgesics - Narcotics

3. Local Analgesics - Block Pain impulses in nerves

Surgical Control of Pain

Achieved through disruption of pain transmission from periphery to spinal cord

Transcutaneous Electrical Nerve Simulation

Electrical stimulation of an electrode on the surface of the skin

Acupuncture

Insertion of fine needles through specific points in the skin to stimulate peripheral nerves

Physical Therapy

Various physical treatment approaches that help acute and chronic pain sufferers

Massage

Eases muscle and other pain; two types:

1. Swedish massage - effleurage, pettrisage

2. Shiatsu massage

Relaxation

Various types of relaxation techniques

1. Progressive muscle relaxation

2. Meditation

3. Meditative relaxation

4. Mindfulness meditation

5. Guided imagery

Distraction

Focusing attention elsewhere

Hypnosis

Altered state of consciousness, involves:

1. Relaxation

2. Distraction

3. Presentation of a suggestion

Does not work for everyone

Multidisciplinary Pain Management Programs

Combination of treatment programs bring the most pain relief to the most patients