title: Disordered conditioned pain modulation system in patients with posttraumatic cold intolerance.
abstract: BACKGROUND
  Conditioned pain modulation (CPM) is a phenomenon of 'pain inhibiting pain' that is important for understanding idiopathic pain syndromes. Because the pathophysiology of posttraumatic cold intolerance is still unknown but it could involve similar mechanisms as idiopathic pain syndromes, we evaluated the functioning of the CPM system in patients with posttraumatic cold intolerance compared to healthy controls.
  
  
  METHODS
  Fourteen healthy controls and 24 patients diagnosed with cold intolerance using the Cold Intolerance Symptom Severity questionnaire were included in the study. Of the 24 patients with cold intolerance, 11 had a nerve lesion and 13 an amputation of one or more digits. To quantify the CPM, pain threshold for mechanical pressure was measured at the affected region as a baseline measure. Then, the contralateral hand received a cold stimulus of ice water to evoke the noxious conditioning. After the cold stimulus, the pain threshold for mechanical pressure was determined again.
  
  
  RESULTS
  The absolute and relative changes in algometer pressure (CPM effect) between pre- and post-conditioning were significantly smaller in the cold intolerance group compared to the control group (absolute p = 0.019, relative p = 0.004). The CPM effect was significantly different between the control group and the subgroups of nerve lesion (p = 0.003) and amputation patients (p = 0.011).
  
  
  CONCLUSIONS
  In this study, we found a CPM effect after a cold stimulus in both controls and patients. A significant weaker CPM effect compared to the controls was found, as in other chronic pain conditions. The CPM system within patients with cold intolerance is altered.
authors.affiliation: Department of Plastic, Reconstructive and Hand Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands. Electronic address: e.smits@erasmusmc.nl.
authors.forename: E S
authors.initials: ES
authors.lastname: Smits
authors.affiliation: Department of Plastic, Reconstructive and Hand Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands; Department of Rehabilitation Medicine and Physical Therapy, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands.
authors.forename: R W
authors.initials: RW
authors.lastname: Selles
authors.affiliation: Pain Treatment Centre, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands.
authors.forename: F J P
authors.initials: FJ
authors.lastname: Huygen
authors.affiliation: Department of Plastic, Reconstructive and Hand Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands.
authors.forename: L S
authors.initials: LS
authors.lastname: Duraku
authors.affiliation: Department of Plastic, Reconstructive and Hand Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands.
authors.forename: S E R
authors.initials: SE
authors.lastname: Hovius
authors.affiliation: Department of Plastic, Reconstructive and Hand Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands.
authors.forename: E T
authors.initials: ET
authors.lastname: Walbeehm
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000673:Amputation, Traumatic / Q000150:complications / Q000503:physiopathology*; D016022:Case-Control Studies; D003080:Cold Temperature / Q000009:adverse effects*; D059328:Diffuse Noxious Inhibitory Control / Q000502:physiology*; D005260:Female; D005383:Finger Injuries / Q000150:complications / Q000503:physiopathology; D005385:Fingers / Q000294:innervation; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000293:injuries; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D059348:Peripheral Nerve Injuries / Q000150:complications / Q000503:physiopathology*; D011312:Pressure / Q000009:adverse effects; D011826:Radial Nerve / Q000293:injuries; D055815:Young Adult
keywords: Amputation; Cold intolerance; Cold sensitivity; Conditioned pain modulation; Diffuse noxious inhibitory control; Nerve lesion