title: Experimental pain responses in children with chronic pain and in healthy children: how do they differ?
abstract: BACKGROUND
  Extant research comparing laboratory pain responses of children with chronic pain with healthy controls is mixed, with some studies indicating lower pain responsivity for controls and others showing no differences. Few studies have included different pain modalities or assessment protocols.
  
  
  OBJECTIVE
  To compare pain responses among 26 children (18 girls) with chronic pain and matched controls (mean age 14.8 years), to laboratory tasks involving thermal heat, pressure and cold pain. Responses to cold pain were assessed using two different protocols: an initial trial of unspecified duration and a second trial of specified duration.
  
  
  METHODS
  Four trials of pressure pain and of thermal heat pain stimuli, all of unspecified duration, were administered, as well as the two cold pain trials. Heart rate and blood pressure were assessed at baseline and after completion of the pain tasks.
  
  
  RESULTS
  Pain tolerance and pain intensity did not differ between children with chronic pain and controls for the unspecified trials. For the specified cold pressor trial, 92% of children with chronic pain completed the entire trial compared with only 61.5% of controls. Children with chronic pain exhibited a trend toward higher baseline and postsession heart rate and reported more anxiety and depression symptoms compared with control children.
  
  
  CONCLUSIONS
  Contextual factors related to the fixed trial may have exerted a greater influence on pain tolerance in children with chronic pain relative to controls. Children with chronic pain demonstrated a tendency toward increased arousal in anticipation of and following pain induction compared with controls.
authors.affiliation: Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1752, USA. jtsao@mednet.ucla.edu
authors.forename: Jennie C I
authors.initials: JC
authors.lastname: Tsao
authors.forename: Subhadra
authors.initials: S
authors.lastname: Evans
authors.forename: Laura C
authors.initials: LC
authors.lastname: Seidman
authors.forename: Lonnie K
authors.initials: LK
authors.lastname: Zeltzer
mesh_terms: D000293:Adolescent; D000344:Afferent Pathways / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002648:Child; D059350:Chronic Pain / Q000503:physiopathology*; D003080:Cold Temperature / Q000009:adverse effects; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D008297:Male; D017288:Pain Threshold / Q000502:physiology*; D011312:Pressure / Q000009:adverse effects; D011795:Surveys and Questionnaires