PAIN

Perception

What hurts more?

PERCEPTION

Two senarios

Perception of pain

“what determines the volume level of symptoms, how is it that some people amplify their symptoms, and others de amplify them?”

Do some individuals “amplify” their symptoms?

Does amplification reflect the fact that patients have different explanatory models for understanding the significance of their pain?

What do we think causes pain? Tissue damage Posture & muscle imbalances

How we typically think of pain

Nociception

Nociception is the process by which intense thermal, mechanical or chemical stimuli are detected by a subpopulation of peripheral nerve fibers, called nociceptors

Their high threshold differentiates nociceptors from sensory neurons

Nociceptors are excited only when stimulus intensities reach the noxious range

located in the dorsal root ganglia (DRG) for the body and the trigeminal ganglion for the face.

Noxious stimuli

An external or internal physical change that induces afferent input in the nervous system, with or without sensory experience or a behavioral response. A noxious stimulus is actually, or potentially, damaging to tissue and liable to cause pain, but does not invariably do so

Nociception is simply a sensory signal indicating potential harm. Pain is a conscious experience, and whether nociception ends up being perceived as pain depends on many more factors.

Pain without nociception is entirely possible

Phantom limb pain

Because phantom limb pain feels so real, it is reasonable to conclude that the body we normally feel is subserved by the same neural processes in the brain; these processes are normally activated and modulated by inputs from the body, but they can act in the absence of any inputs

Neuromatrix

What we think causes it

Postural Structural Biomechanical Model

Misalignments can “impose excessive stress on the spine leading to degeneration/damage or dysfunction and eventually to painful back conditions

In this model, the imbalances and symmetries increase the abnormal mechanical/physical stresses imposed on the musculoskeletal system. This may lead recurrent injury or the development chronic conditions through a gradual process of wear-and-tear

Does poor posture really equal pain?

“does it really matter if these PSB factors or minor control changes exist and would they cause some catastrophic failure in the musculoskeletal system?”

“the spine can undergo profound physical changes that are well tolerated without the development of a symptomatic condition.”

Biological Reserves and Tolerance

Biological reserve allows for such losses without a negative effect on spinal function or the development of a condition.

The system is capable of tolerating and compensating for these factors within the available surplus.

Trunk stabilization is achieved by what level of contraction?

Add 32 kg weight to the torso- now what?

Muscle Imbalances?

“whether insufficient or excessive, a deviation from optimal extensibility is thought to precipitate unusual wear and tear on capusular structures and articular surfaces of involved joints. It is suggested that deviations from optimal extensibility contribute to muscle imbalances, faulty posture, and dysfunctional movement. Although guidelines for what constitutes insufficient, optimal, and excessive extensibility measurements are based on the science of kinematics, their clinical validity has rarely been studied.

Chronic Pain

alterations of the pain pathway lead to hypersensitivity, such that pain outlives its usefulness as an acute warning system and instead becomes chronic and debilitating

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2852643/

GOOD

ANNOYING

Nociceptive pain is an adaptive alarm system, persistent pain is maladaptive

Essentially an ongoing false alarm

Central sensitization

Net Effect: recruitment of previously subthreshold inputs to cause pain

Produces pain hypersensitivity

Allodynia Hperalgesia

Fear avoidance

“higher fear avoidance, sensory pain, anxiety, depression, disability, and response to pain provocation test. This group demonstrated a greater likelihood of having allodynia (pain in response to non noxious stimuli) and was judged to have a dominant psychosocial component to presentation”

At baseline may predict chronicity

Short version

Long versionn