Acute Pain
- Usually associated with recent or ongoing tissue damage.
- short term.
Chronic Pain
- Persisted beyond the normal expected healing period.
- Pain which has lasted for at least 3-6 months.
What percentage of adults in Canada suffer from chronic pain?
20%
Canadian cost of chronic pain
- Over 37 billion per year
- Including 6 billion in direct health- care costs.
- Typical annual cost of care per pain patient waiting for treatment at Canadian pain clinics is 17, 544$.
IASP
- International Association for the Study of Pain
- The most influential group of pain researchers.
Pain
- An unpleasant sensory and emotional experience associated with actual or potential damage, or described in terms of such damage.
Sensation
The Process by which stimulation of a sensory receptor gives rise to neural impulses that result from an experience outside the body.
Nociception
The processing of stimuli associated with the stimulation of nociceptors and has that potential of being experiences as pain.
Pain and Depression
31-100% of people with chronic pain also suffer from depression & anxiety.
- also high comorbidity with alcoholism and non-prescribed drugs.
Social Consequences of Chronic Pain
- disruption of social relationships
- social isolation
- reduced quality of life
Specificity Theory
The greater the tissue damage, the greater the pain
The Gate Control Theory
The theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain. The “gate” is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.
Neuromatrix Model
The body is perceived as a unit and is identified as the “self” distinct from its surroundings. The perception of the body with everything felt from the body including pain, is produced by a central neural process, called the neuromatrix.
Neuromatrix
A widespread network of neurons that form loops between the cortex and the limbic system as well as the thalamus and the cortex. The neuronal loops separate to allow for parallel processing in different components of the neuromatrix and come together repeatedly to permit interactions between the processing outputs.
Neurosignature
Characteristic inputs from the body undergo cyclical synthesis so that patterns are impressed on them in the neuromatrix. The repeated cyclical processing and synthesis of nerve impulses through the neruromatrix reveal a characterstic pattern, which is the neurosignature.
Biopsychosocial Models of pain
Focus on the interplay of biological psychological and social parameters in pain.
What do biomedical models fail to explain?
- Effect of hypnosis on pain
- Role of coping styles
- success of psychological intervention on chronic pain management
The Operant Model
- Stresses the importance of reinforcement in the development and maintenance of pain behaviour.
- Fails to take into account interpretations and appraisals of pain.
Fear Avoidance Model of Pain
- Certain movements and behaviours become associated with pain or exacerbations of pain, when couples with catastrophic thoughts about pain and concern about the possibility of reinjury, can lead to excessive avoidance.
The Communications Model of Pain
A three step A-B-C process:
a) the internal experience of pain
b) encoding in expressive behaviour
c) decoding
Cognitive Behavioural Conceptualization of Pain
Focus on the role of cognitive factors and beliefs in the pain experience and recognize the interconnections among thoughts, feelings and behaviours.
- the assumption that a fundamental difference between those who adjust well to pain and those who do not lies in their appraisals and interpretations of the situation
`Psychological Assessment of Pain
- based on biopsychosocial formulations of the pain experience
- focuses on a variety of domains capturing information about the person, psychological and problem history, co-morbidities, coping styles, dimensions of the pain experience, functional analysis pain behaviour and impact of pain on quality of life.
The McGill Pain Questionnaire
- Groups of words designed to capture various dimensions of the pain experience
- patient can select pain descriptors
- contains line drawings where the patient can mark the spatial distribution of pain
- 1-5 rating scale for pain
Pain Dimensions MPQ Assesses
- sensory
- Affective
- Evaluative
