The journal of pain : official journal of the American Pain Society
-
Posttraumatic stress disorder (PTSD) and chronic pain often co-occur and exacerbate each other. Elucidating the mechanism of this co-occurrence therefore has clinical importance. Previously, patients with PTSD with chronic pain were found to demonstrate a unique paradoxical pain profile: hyperresponsiveness together with hyposensitivity to pain. Our aim was to examine whether 2 seemingly paradoxical facets of PTSD (anxiety and dissociation) underlie this paradoxical profile. Patients with PTSD (n = 32) and healthy control individuals (n = 43) underwent psychophysical testing and completed questionnaires. Patients with PTSD had higher pain thresholds and higher pain ratings to suprathreshold stimuli than control individuals. Pain thresholds were positively associated with dissociation levels and negatively associated with anxiety sensitivity levels. Experimental pain ratings were positively associated with anxiety sensitivity and negatively related to dissociation levels. Chronic pain intensity was associated with anxiety, anxiety sensitivity, and pain catastrophizing. It appears that reduced conscious attention toward incoming stimuli, resulting from dissociation, causes delayed response in pain threshold measurement, whereas biases toward threatening stimuli and decreased inhibition, possibly caused by increased anxiety, are responsible for the intensification of experimental and chronic pain. The paradoxical facets of PTSD and their particular influences over pain perception seem to reinforce the coexistence of PTSD and chronic pain, and should be considered when treating traumatized individuals. ⋯ This article provides new information regarding the underlying mechanism of the coexistence of PTSD and chronic pain. This knowledge could help to provide better management of PTSD and chronic pain among individuals in the aftermath of trauma.
-
It has been assumed that patients with chronic disorders of consciousness (DOC) do not feel pain, but it is possible that some of them just cannot report it. Modulation of γ-band oscillatory activity (γBO) in centroparietal areas (considered as a marker of either subjective pain perception processes or pain-related motor behavior preparation) by part of the anterior cingulate cortex (ACC) has been proposed to be suggestive of conscious pain perception and could therefore be used to assess the maintenance of some level of conscious pain perception in patients with DOC. Hence, we used a repetitive transcranial magnetic stimulation (rTMS) approach in an attempt to trigger frontoparietal output. We enrolled 10 healthy participants (HC), 10 patients in a minimally conscious state (MCS), and 10 with unresponsive wakefulness syndrome (UWS), who underwent a 1-Hz rTMS protocol over ACC. Before and after the neurostimulation paradigm, we measured the pain-rating assessment (pVAS), γBO, latency, and the amplitude of cortical nociceptive potentials evoked by transcutaneous electric sinusoidal stimuli (EEP). In all the HC and MCS and in 2 of the UWS subjects, rTMS increased γBO and reduced the EEP amplitude, whereas pVAS scoring improved in the HC. Our findings provide some evidence about conscious pain processing even in patients with severe DOC and show that rTMS over ACC may be a useful approach to better investigate the level of conscious impairment. ⋯ Patients with DOC may not be able to respond to pain stimuli, although they may feel it. The possibility of detecting residual pain perceptions by means of a noninvasive neuromodulation paradigm, studying the correlation between the ACC and centroparietal γBO, may help clinicians to better assess pain in such individuals.