In an article recently published in Pain, researchers at the University of Leuven, Belgium propose a model for the transition from acute to chronic pain, based on fear-avoidance.1

With this model, which describes the distinct behaviors underlying perpetuation of or breaking from pain, researchers seek to guide pain-related research as well as pain management. In this model, conditioning plays a central role in the maintenance of pain, and authors argue that its disruption may lead to recovery.

Pain has biological value, as it indicates threat to the individual’s integrity and triggers fear and associated protective behaviors (eg, heightened arousal, withdrawal and avoidance), all of which contribute to self-preservation.

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In the proposed model, an initial nociceptive stimulus triggers pain, which is perceived by the individual as a threat of either low or high grade. A low grade threat in conjunction with a positive affect (eg, optimism) will result in prioritization of “valued life goals”, enabling identification of the adequate approach to reach recovery.

When pain is perceived as a high threat and associated with a negative affect (eg, representation of harm), priority is given to pain control, leading sequentially to fear, avoidance, interference and further negative affect, a series of events which promote the persistence of pain.

Acquisition of Pain In the present model, pain-associated threat results in fear, triggering adaptive learning. Initially, the pain experience may be associated with neutral cues (acting as the conditioned stimuli, CS), resulting in conditioned responses (CR; eg, fear, avoidance or safety-seeking).

Pain as an unconditioned stimulus (US), on the other hand may yield unconditioned responses (UR) of selective attention and escape.

Generalization of Pain “Chronic pain may develop when pain-related fear and avoidance persists despite healing or when protective responses generalize to novel situations (GS) that share features with the CS,” postulate the authors.

Avoidance This behavior, which initially serves to delay or protect from harmful stimuli, is central to the proposed model. However, as noted here, “avoidance behavior, once acquired, is notoriously persistent, and usually maintains pain-related fear.”

Avoidance behavior interferes with positive activities and promotes negative affect, both of which contribute to the maintenance of pain.

Extinction of Pain According to this model, prioritizing alternate life goals through optimism and positive affect over pain-associated behaviors perpetuated by negative affect (ie, fear and avoidance), provides the means to break the pain cycle promoted by avoidance and other protective behaviors.

Thus, “inhibitory responses can be learned when avoidance behavior is omitted, and the individual is exposed to the stimuli and situations that were previously avoided,“ note scientists. By creating new and threat-free associations with CSs, the initial conditioning may be disrupted, allowing for individuals to be exposed to previously avoided situations.

Such treatments targeting pain-related fear, aimed at decoupling fear and CSs through novel exposures, have proven effective in treating complex regional pain syndrome in youth and post-traumatic neck pain.2,3

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  1. Vlaeyen JW, Crombez G, Linton SJ. The fear-avoidance model of pain. Pain. 2016;157(8):1588-9.
  2. Simons LE. Fear of pain in children and adolescents with neuropathic pain and complex regional pain syndrome. Pain. 2016;157 Suppl 1:S90-7.
  3. De jong JR, Vangronsveld K, Peters ML, et al. Reduction of pain-related fear and disability in post-traumatic neck pain: a replicated single-case experimental study of exposure in vivo. J Pain. 2008;9(12):1123-34.