Psychological trauma is associated with an increased risk for chronification of nonspecific chronic back pain (nsCLBP) independent of posttraumatic stress disorder (PTSD). However, the mechanisms underlying the role of psychological trauma in nsCLBP are less clear than in PTSD. Therefore, this study considered whether psychological trauma exposure (TE) is accompanied by specific alterations in pain perception. The study included 56 participants with nsCLBP and TE (nsCLBP-TE), 93 participants with nsCLBP without TE (nsCLBP-W-TE), and 31 pain-free controls. All participants underwent a thorough clinical evaluation. The standardized quantitative sensory testing protocol of the “German Research Network on Neuropathic Pain” was used to obtain comprehensive profiles on somatosensory functions in painful (back) and non-painful areas (hand). The protocol consisted of thermal and mechanical detection as well as pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. Psychological trauma was validated by structured clinical interview. Trauma-associated symptom severity, anxiety, and depressive symptomatology were assessed by self-report questionnaires. Differences in somatosensory function were seen only for pressure pain thresholds. Compared with controls, nsCLBP-TE revealed hyperalgesia generalized in space with lower thresholds in painful and non-painful areas, whereas nsCLBP-W-TE demonstrated localized alterations with decreased thresholds only in the pain-affected area of the back (P ≤ 0.006). Our findings suggest an augmented central pain processing in nsCLBP-TE (alterations in painful and non-painful areas), whereas nsCLBP-W-TE show only local changes (alterations only in the painful area) suggesting regional sensitization processes. This finding might explain why TE without PTSD is associated with an increased prevalence of chronic pain.
Nonspecific back pain subjects without trauma demonstrated localized pain conditions, whereas back pain subjects with trauma revealed hyperalgesia to deep pain modalities generalized in space.
aDepartment of General Internal Medicine and Psychosomatics, Medical Hospital, University of Heidelberg, Heidelberg, Germany
bDepartment of Neurophysiology, Centre for Biomedicine and Medical Technology Mannheim (CBTM), University of Heidelberg, Heidelberg, Germany
Corresponding author. Address: Department of General Internal Medicine and Psychosomatics, Medical Hospital, University of Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany. Tel.: +49 6221 56 37862; fax: +49 6221 56 5749. E-mail address: email@example.com (J. Tesarz).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received July 28, 2014
Received in revised form November 24, 2014
Accepted December 16, 2014