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ObjectiveAlthough posttraumatic stress disorder (PTSD) and chronic pain frequently occur in tandem, the pathophysiological mechanisms mediating this comorbidity are poorly understood. Because excessive inflammation occurs in both conditions, we examined the cerebrospinal fluid (CSF) concentrations of inflammatory response mediators interleukin 1-beta (IL-1β), interleukin 6 (IL-6), interleukin 8 (IL-8), tumor necrosis factor-alpha (TNFα) and interleukin 10 (IL-10) after prolonged suprathreshold pain stimulus in 21 male combat veterans; 10 with PTSD and 11 combat controls (CC).MethodsAfter completing baseline quantitative sensory testing (QST) and psychological profiling, all patients received an injection of capsaicin into the quadriceps muscle. Spontaneously reported pain was measured for 30min after the capsaicin injection. The evoked pain measure of temporal summation was tested between 70 and 110min post capsaicin injection. Inflammatory (IL-1β, IL-6, IL-8 TNFα) and anti-inflammatory (IL-10) CSF cytokines were measured before (baseline) and after capsaicin injection over a time frame of 110min.ResultsFollowing intramuscular capsaicin injection, pro-inflammatory cytokines [TNFα, IL-6, IL-8] significantly increased (percent rise from baseline) in both groups, whereas IL-1β significantly increased in the PTSD group only. The anti-inflammatory cytokine IL-10 showed an immediate (within 10min) increase in the CC group; however, the IL-10 increase in the PTSD group was delayed and not consistently elevated until 70min post injection.ConclusionThese findings show significant central nervous system (CNS) differences in the inflammatory response to a deep pain stimulus in combat veterans with and without PTSD. They support the concept that abnormally elevated neuroinflammatory response to pain stimuli may be one CNS mechanism accounting for the high co-occurrence of PTSD and pain.

Objective pain assessment methods pose an advantage over the currently used subjective pain rating tools. Advanced signal processing methodologies, including the wavelet transform (WT) and the orthogonal matching pursuit algorithm (OMP), were developed in the past two decades. The aim of this study was to apply and compare these time-specific methods to heart rate samples of healthy subjects for acute pain detection. Fifteen adult volunteers participated in a study conducted in the pain clinic at a single center. Each subject's heart rate was sampled for 5-min baseline, followed by a cold pressor test (CPT). Analysis was done by the WT and the OMP algorithm with a Fourier/Wavelet dictionary separately. Data from 11 subjects were analyzed. Compared to baseline, The WT analysis showed a significant coefficients' density increase during the pain incline period (p

BackgroundPost-traumatic stress disorder (PTSD) and pain have a well-documented high comorbidity; however, the underlying mechanisms of this comorbidity are currently poorly understood. The aim of this psychophysical study was to investigate the behavioral response to a prolonged suprathreshold pain stimulus in subjects with combat-related PTSD and combat controls (CC) for clinical evidence of central sensitization.MethodsTen male subjects with current PTSD related to combat and 11 CC male subjects underwent baseline quantitative sensory testing (QST), temporal pain summation, and psychological profiling followed by an intramuscular injection of capsaicin into the quadriceps muscle.ResultsThere was no significant between-group difference for the initial maximal pain response or an initial pain reduction for the first 15 minutes postinjection on QST or pain ratings. However, we observed significantly higher scores in the PTSD group for the second 15 minutes postinjection on both pain intensity and pain unpleasantness ratings. Assessment of temporal summation to repetitive pressure stimuli showed significantly higher subjective pain in the PTSD group.ConclusionThese findings are consistent with a significantly higher degree of acute central sensitization in individuals with PTSD. Increased acute central sensitization may underlie increased vulnerability for developing pain-related conditions following combat trauma.

BackgroundPost-traumatic stress disorder (PTSD) and pain have a well-documented high comorbidity; however, the underlying mechanisms of this comorbidity are currently poorly understood. The aim of this psychophysical study was to investigate the behavioral response to a prolonged suprathreshold pain stimulus in subjects with combat-related PTSD and combat controls (CC) for clinical evidence of central sensitization.MethodsTen male subjects with current PTSD related to combat and 11 CC male subjects underwent baseline quantitative sensory testing (QST), temporal pain summation, and psychological profiling followed by an intramuscular injection of capsaicin into the quadriceps muscle.ResultsThere was no significant between-group difference for the initial maximal pain response or an initial pain reduction for the first 15 minutes postinjection on QST or pain ratings. However, we observed significantly higher scores in the PTSD group for the second 15 minutes postinjection on both pain intensity and pain unpleasantness ratings. Assessment of temporal summation to repetitive pressure stimuli showed significantly higher subjective pain in the PTSD group.ConclusionThese findings are consistent with a significantly higher degree of acute central sensitization in individuals with PTSD. Increased acute central sensitization may underlie increased vulnerability for developing pain-related conditions following combat trauma.

BackgroundPost-traumatic stress disorder (PTSD) and pain are highly comorbid.ObjectiveThe purpose of this study was to examine the association of PTSD with specific pain complaints in veterans of Operations Enduring and Iraqi Freedom (OEF/OIF).MethodA total of 381 primarily male (88.5%) veterans with a mean age of 30 years completed a battery of self-report questionnaires. A positive PTSD screen was defined as a score of ≥40 on the Davidson Trauma Scale. Logistic regression was used to examine the association of positive PTSD screen with specific pain complaints.ResultsThere were no significant demographic or physical and mental health differences between veterans who screened positive for PTSD only and those with PTSD and at least one pain complaint, although differences on rates of combat injury and depression approached significance. Veterans who screened positive for PTSD were 2 to 3 times more likely to report abdominal pain, muscle aches or cramps, and joint aches, even after controlling for age, gender, combat injury, and depression.ConclusionsSimilar to findings in other populations, there is a relationship between PTSD and pain complaints in OEF/OIF veterans. Future research should examine the mechanisms that link PTSD with specific pain complaints, especially abdominal pain.