PTSD Impact on Axial Pain Following Motor Vehicle Collisions

It is thought that a mutual relationship between pain and PTSD gives rise to chronic pain syndromes.
It is thought that a mutual relationship between pain and PTSD gives rise to chronic pain syndromes.

Post-traumatic stress disorder (PTSD) symptoms after motor vehicle collisions (MVCs) contribute substantially to ongoing axial pain throughout the year following the accident, according to a study recently published in Pain.1

The multicenter prospective study found that in the early weeks and at least up to a year following an MVC, axial pain contributed to the development of PTSD symptoms, consisting of the maintenance of  a state of hyperarousal and the constant intrusion of thoughts and memories of the accident, which contributed to the continuation of a pain cycle.

This finding adds to a significant body of research from the past 15 years that supports the hypothesis of a mutual relationship between pain and PTSD that gives rise to chronic pain syndromes.2,3 A study investigating the association between pain and PTSD in veterans reported that “these 2 conditions co-occur at a high rate and may interact in such a way as to negatively impact the course of either disorder.”2

A number of earlier studies have also pointed to mechanisms by which cognitive interventions aimed at reducing pain may lead to the activation of stress pathways, thus affecting neurosensory processing.3,4

The current study evaluated correlations between pain and PTSD at 6 weeks, 6 months, and 1 year following an MVC in a cohort of 948 patients age 18 to 65, including 575 women and 373 men, who presented to the emergency department (ED) in 8 US states from 2009 to 2011.

A consistent subset of patients had overlapping PTSD and axial pain symptoms throughout the year following the MVC. The majority of patients treated in the ED (median time = 1.2 h post-MVC) had severe axial pain (n=660/993, 71%). Of the 948 patients enrolled in the study, 377 (58%) reported pain only, and 78 (22%) were diagnosed with PTSD only, while 274 (29%) were identified as experiencing both PTSD and axial pain.

The number of patients affected by PTSD decreased with time, with 50 patients (23%) at 6 weeks, and 27 patients (23%) at 6 months and 1 year. Similarly, the number of patients experiencing axial pain lowered over the study period, with 271/859 patients (62%) affected at 6 weeks, 201/840 patients (67%) at 6 months, and 182/861 patients (66%) at 1 year.

The most significant correlation observed was that between PTSD and axial pain, which increased steadily from r=0.12 at 6 weeks to r=0.43 at 1 year. This observation supports the hypothesis that “axial pain after MVC consistently promotes the maintenance of hyperarousal and intrusive symptoms,” according to the researchers.

Specific PTSD symptom clusters were closely aligned with reported pain, although different symptom clusters were influential at different time points, the investigators pointed out. Hyperarousal at 6 weeks was strongly predictive of axial pain severity and of other PTSD signs at 6 months (but only in patients with genetic  vulnerability to stress-related pain, as indicated by ≥1 copy of the glucocorticoid receptor co-chaperone FKBP5 risk haplotype),5 while intrusion and avoidance symptoms were not. This pattern was reversed at 6 months; symptoms of intrusion predicted axial pain severity at 12 months, while signs of hyperarousal and avoidance did not.

Limitations

The study population was ethnically limited to European Americans, and did not allow for generalization to other ethnic groups.

The employed methodology did not allow assessment of the influence of PTSD symptom clusters.

The study did not explore the role of individual cognitive factors such as catastrophizing, physical health, and beliefs.

 

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References

  1. Feinberg RK, Hu J, Weaver MA, et al. Stress-related psychological symptoms contribute to axial pain persistence after motor vehicle collision: path analysis results from a prospective longitudinal study. Pain 158(2017)682-690.
  2. Otis JD, Keane TM, Kerns RD. An examination of the relationship between chronic pain and post-traumatic stress disorder. J Rehabil Res Dev 2003;40:397-405.\Sharp TJ. The prevalence of post-traumatic stress disorder in chronic pain patients. Curr Pain Headache Rep (2004);8:111-115.
  3. McLean SA, Clauw DJ, Abelson JL, et aI. The development of persistent pain and psychological morbidity after motor vehicle collision : integrating the potential role of stress response systems into a biopsychosocial model. Psychosom Med 2005;67:783-790.
  4. Bortsov AV, Smith JE, Diatchenko L, et al. Polymorphisms in the glucocorticoid receptor co-chaperone FKBP5 predict persistent musculoskeletal pain after traumatic stress exposure. Pain. 2013;154(8):1419-1426.
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