Chronic Pain and PTSD: The Perpetual Avoidance Model and its Treatment Implications

Summarized by Kyle Ballard

Comorbidity of chronic pain and PTSD

It is first important to recognize the coincidence of PTSD and chronic pain in trauma survivors. In one study, the presence of chronic pain in PTSD patients can range from 34-80% depending on the population studied. However, the presence of PTSD in chronic pain patients can be anywhere from 10-50%. This discrepancy is largely thought to be due to the fact that many traumatic events are linked with physical injury. This relationship has been described as a meditation effect, where memories of the traumatic event are evaluated more negatively because of the accompanying physical pain inflicted.

Risk factors for PTSD and chronic pain

In a large metaanalysis, there have been several variables identified as predictors of PTSD, these include a traumatic event of substantial intensity, a lack of social support following the event, and additional life stresses on top of the traumatic experience. Also, being female, having endured prior trauma, having a history of psychopathology, and experiencing a traumatic manmade event (like rape) as opposed to a natural disaster, are also risk factors. In PTSD, it is the behavioral factors such as perceived uncontrollability, negative appraisal of the trauma and its consequences, and maladaptive strategies like avoidance, that are primary concern. It is these behaviors that often lead to maintenance of chronic pain, and associated catastrophizing and kinesiophobia. Research also suggests it is often not the severity of the physical trauma that predicts pain, rather it is presence of these psychological and social risk factors that put PTSD patients at greater risk for chronic pain maintenance.

Development and Maintenance of PTSD and chronic pain

Both PTSD and chronic pain have similar models which describe their maintenance, with maladaptive cognitive processes being the most crucial in both. For pain, the ‘fear avoidance’ model is most important, as it stresses the role of catastrophic appraisal following a pain event, fear of pain, and avoiding activities that may cause more pain. As for pain following a traumatic event, the best predictor of disability is the presence of PTSD, and not necessarily the nature or extent of the injuries. Because the remarkably high coincidence of these conditions, the Perpetual Avoidance Model (PAM) has been formed to demonstrate the mutual maintenance of these two illnesses.

The Perpetual Avoidance Model (PAM)

The PAM consists of two overlapping behavioral realms: the PTSD model and the ‘PAIN’ model. One of key overlaps is bodily hyperarousal in PTSD, a result of a “here and now” response to an intrusive memory of the traumatic event. This hyperarousal then has the capacity to increase pain sensation within the PAIN model, leading to fearavoidance behaviors that often limit the patient’s comfort level with activities and movements. Biologically, hyperarousal in PTSD presents itself as increased sympathetic drive, which has been studied to be correlated with greater physical impairment in chronic back pain patients. It should now be apparent how the coexistence of these conditions can be a vicious cycle of mutual maintenance, primarily through the overlapping characteristics of fear avoidance beliefs and subsequent lack of activity, and through increased pain sensation from increased sympathetic drive and inactivity. There are however effective treatment options in cognitivebehavioral therapies, which seek to improve pain and activity by focusing on cognitive variables like beliefs about pain, recognizing catastrophizing thoughts, and improving painself efficacy.

Treatment Implications

Important things to focus on in treating traumatized patients with chronic pain:
  • Educate the patient about the relationship between chronic pain and PTSD, focusing on topics like avoidance, hyperarousal, pain sensation, and catastrophizing.
  • Focus on recognizing and reducing avoidant behaviors that may lead to inactivity. Treatments like exposure therapy are effective by confronting patients with their stressful events and teaching them how to appraise it as part of the past, in order to reduce a hyperarousal response and subsequent pain sensitivity.
  • Exposure therapy for chronic pain is also effective by showing patients how they can move in ways that were previously thought to be harmful and they learn new ways to cope and perceive pain sensations in a less avoidant way. Gradually easing patients back into an exercise program is an effective way to break the cycle of pain and inactivity.
  • Progressive Muscle Relaxation and diaphragmatic breathing can be effective in reducing arousal. Biofeedback using EMG can be an effective way for patients to recognize their abnormal muscle tension in an area, and then can later learn how to reduce muscle tension and relieve pain as a result.
To summarize, treatment for traumatized patients suffering from PTSD and chronic pain should include a biopsychosocial approach, combining education of the maladaptive behaviors leading to disability, as well as exposure therapy, relaxation, biofeedback, and therapeutic exercise.

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