Pain models Flashcards
Pain gate theory Melzack and wall 1965
Sensory inputs from nociceptors synapse with neurons in the spinal cord, where signals compete, and the dominant input is transmitted to the brain.
Nociceptors synapse with second-order neurons in the dorsal horn, where synaptic weighting occurs between different sensory inputs. If non-noxious stimuli are more strongly represented, nociceptive transmission may be inhibited, leading to a reduced perception of pain.
C-fibers and A-delta fibers transmit pain signals to the dorsal horn, where they ascend via the spinothalamic tract to the thalamus.
In contrast, A-beta fibers, which convey touch, pressure, and vibration, activate inhibitory interneurons in the spinal cord. This reduces nociceptive transmission and helps modulate pain perception.
Pain relief techniques work by stimulating A-beta fibers, which help “close the pain gate” in the spinal cord, reducing pain signals sent to the brain. Here’s how different therapies help:
Manual therapy
Mobilisations
TEND
Hot cold therapy
proprioceptive work
Does not consider the influences of any cognitive/motivational/emotional dimensions or contextual factors The many complexities of pain
Mature organism Gifford 1998
This model views pain as part of a broader protective response controlled by the nervous system. The body continuously assesses and interprets threats based on sensory, cognitive and environmental factors.
Pain is not simply a direct response to damage but a result of how the brain processes information
The nervous system adapts over time, meaning persistent pain can result from heightened sensitivity rather than ongoing damage
Pain education
Helps explain why pain can persist even after an injury has healed.
Supports gradual reintroduction of movement to reduce sensitivity and fear avoidance behaviors
Encourage the use of stress reduction to modify pain perception.
Emphasizes the role of belief, environment and past pain.
Relates to education about pain not equally tissue damage. Education about fear of movement.
Graded exposure where we slowly introduce movements to reduce pain sensitivity
Relaxation
Adjusting lifestyle factors
BUT
Difficult to apply to those who have very strong beliefs about pain
Requires time
Patients may reject psychological treatment if they have come for manual therapy.
However, applying manual therapy, may help reduce pain and in turn will increase their confidence surrounding pain as we help them alleviate fear. Of movement.
Neuro-matrix
Melzack (1990)
Expands on gate theory, that pain is not just a direct result of injury but is generated by a network of neurons called the neuromatrix. Pain is produced by a combination of sensory, cognitive and emotional inputs meaning that past experiences, thoughts and emotions all influence pain perception.
The pain neuromatrix creates a unique pain signature based on individuals
The NeuroMatrix model
Cognitive evaluation
Sensory discrimination
Motivational affective
First model to describe why pain can persist after healing and how pain is not always equal to damage
Pattern theory
Pattern theory – Different areas of the brain contribute to pain. Signature within the brain exists when pain is caused, explains why pain can persist after there is no sensory input.
If there is a pain sensation- there is a pain signature in the brain plays out
Although there is no specific pattern for pain.
The pain matrix may not exist in the way we think it does. A signature of salience rather than specific, tough pain or auditory.
Pattern theory did not work to explain hoe BPS influences pain
BPS Engal 1990
An assessment should include
Attitude, beliefs
Behavior
Economy
Emotion
Social life
Gifford 2002 – shopping basket approach
ABCDEFW
Can help clinicians work outside of the medical model and understand how different issues that may be influenced by patient’s presentations and experiences.
Helps to explain that pain is multifactorial and should be assessed and treated not only as a biological symptom.
Patient centered approach to care.
Not a model of pain, but helpful to investigate how thoughts feeling and behaviors can influence people
predictive Processing (2015)
The brain constantly makes predictions about the sensory environment
The brain continuously compares predicted sensory information with actual sensory feedback.
In the context of pain, it suggests that the brain doesn’t passively receive pain signals but actively predicts and interprets pain based on experience, context and prior beliefs.
The brain interprets signals and can generate pain with the absence of actual tissue damage.
Pain may persist if the brain is overpredicting danger.
Helps to explain placebo, nocebo effect, if we believe something is happening then it may help pain.
Belief about diagnosis, can amplify pain.
Helps to explain chronic pain or psychogenic pain, the brain continues to predict pain in response to harmless stimuli due to maladaptive prediction patterns.
Graded exposure that challenges their pain predictions, showing them, movements are same and over time the brain will update its prediction model and reduce pain sensitivity.
