title: Preterm births: can neonatal pain alter the development of endogenous gating systems?
abstract: Prematurity is known to affect the development of various neurophysiological systems, including the maturation of pain and cardiac circuits. The purpose of this study was to see if numerous painful interventions, experienced soon after birth, affect counterirritation-induced analgesia (triggered using the cold pressor test) later in life. A total of 26 children, between the ages of 7 and 11 participated in the study. Children were divided into three groups, according to their birth status (i.e., term-born, born preterm and exposed to numerous painful interventions, or born preterm and exposed to few painful interventions). Primary outcome measures were heat pain thresholds, heat sensitivity scores, and cardiac reactivity. Results showed that preterm children and term-born children had comparable pain thresholds. Exposure to conditioning cold stimulation significantly increased heart rate and significantly decreased the thermal pain sensitivity of term-born children. These physiological reactions were also observed among preterm children who were only exposed to a few painful interventions at birth. Changes in heart rate and pain sensitivity in response to conditioning cold stimulation were not observed in preterm children that had been exposed to numerous painful procedures during the neonatal period. These results suggest that early pain does not lead to enhanced pain sensitivity when premature babies become children, but that their endogenous pain modulatory mechanisms are not as well developed as those of children not exposed to noxious insult at birth. Greater frequency of painful procedures also dampened the rise in heart rate normally observed when experimental pain is experienced.
authors.affiliation: Université de Sherbrooke, Faculté de Médecine, Neurochirurgie, 3001, 12(e) Avenue nord, Sherbrooke, Québec, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Goffaux
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lafrenaye
authors.forename: Mélanie
authors.initials: M
authors.lastname: Morin
authors.forename: Hugues
authors.initials: H
authors.lastname: Patural
authors.forename: Geneviève
authors.initials: G
authors.lastname: Demers
authors.forename: Serge
authors.initials: S
authors.lastname: Marchand
mesh_terms: D000344:Afferent Pathways / Q000254:growth & development / Q000503:physiopathology*; D002648:Child; D003080:Cold Temperature / Q000009:adverse effects; D003955:Diagnostic Tests, Routine / Q000009:adverse effects; D004750:Enteral Nutrition / Q000009:adverse effects; D005260:Female; D006339:Heart Rate; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D007267:Injections / Q000009:adverse effects; D015931:Intensive Care, Neonatal; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D017288:Pain Threshold / Q000502:physiology*; D012121:Respiration, Artificial / Q000009:adverse effects / Q000706:statistics & numerical data