title: Paradoxical Pain Perception in Posttraumatic Stress Disorder: The Unique Role of Anxiety and Dissociation.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Physical Therapy, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel. Electronic address: rutidef@post.tau.ac.il.
authors.forename: Ruth
authors.initials: R
authors.lastname: Defrin
authors.affiliation: Department of Psychiatry, Sourasky Medical Center, Tel-Aviv University, Tel-Aviv, Israel; Department of Psychiatry, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Shaul
authors.initials: S
authors.lastname: Schreiber
authors.affiliation: Bob Shapell School of Social Work, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Karni
authors.initials: K
authors.lastname: Ginzburg
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001007:Anxiety / Q000503:physiopathology*; D058443:Catastrophization; D004213:Dissociative Disorders / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology; D010812:Physical Stimulation; D011601:Psychophysics; D013313:Stress Disorders, Post-Traumatic / Q000150:complications* / Q000523:psychology*; D011795:Surveys and Questionnaires
keywords: Chronic pain; anxiety; dissociation; hyperresponsiveness; hypoalgesia; posttraumatic stress disorder; psychophysics