Cry presence and amplitude do not reflect cortical processing of painful stimuli in newborns with distinct responses to touch or cold

Abstract

Objective Newborns requiring hospitalisation frequently undergo painful procedures. Prevention of pain in infants is of prime concern because of adverse associations with physiological and neurological development. However, pain mitigation is currently guided by behavioural observation assessments that have not been validated against direct evidence of pain processing in the brain. The aim of this study was to determine whether cry presence or amplitude is a valid indicator of pain processing in newborns. Design Prospective observational cohort. Setting Newborn nursery. Patients Healthy infants born at >37 weeks and <42 weeks gestation. Interventions We prospectively studied newborn cortical responses to light touch, cold and heel stick, and the amplitude of associated infant vocalisations using our previously published paradigms of time-locked electroencephalogram (EEG) with simultaneous audio recordings. Results Latencies of cortical peak responses to each of the three stimuli type were significantly different from each other. Of 54 infants, 13 (24%), 19 (35%) and 35 (65%) had cries in response to light touch, cold and heel stick, respectively. Cry in response to non-painful stimuli did not predict cry in response to heel stick. All infants with EEG data had measurable pain responses to heel stick, whether they cried or not. There was no association between presence or amplitude of cries and cortical nociceptive amplitudes. Conclusions In newborns with distinct brain responses to light touch, cold and pain, cry presence or amplitude characteristics do not provide adequate behavioural markers of pain signalling in the brain. New bedside assessments of newborn pain may need to be developed using brain-based methodologies as benchmarks in order to provide optimal pain mitigation.

Crying out in pain—A systematic review into the validity of vocalization as an indicator for pain

“…Nevertheless, crying was categorized as a vocal behaviour in some of the included studies. In four out of five included studies where crying was the only vocalization investigated, an association between crying and pain was found (Büttner & Finke, 2000;Dale, 1989;Maitre et al, 2017;Rossato & Angelo, 1999;Warnock, 2003). One of those studies was in neonates.…”

“…Of studies that did not find an association, five out of six included only one type of vocalization in their investigation, e.g. only sighing or only verbalization (Maitre et al, 2017;Robbins et al, 2011;Shega et al, 2008;Stanford et al, 2005;Waters et al, 2008). Possibly, not only the quantity of different vocalizations contributes to the association with pain, but also the type of vocalization.…”

“…In the studies investigating acute pain, however, the results were very different. Seven out of eight studies found an association between acute pain and vocalization (Büttner & Finke, 2000;Dale, 1989;Dubois, Bringuier, Capdevilla, & Pry, 2008;Elander, Hellstrom, & Qvarnstrom, 1993;Maitre et al, 2017;Manfredi, Breuer, Meier, & Libow, 2003;Oueriagli Nabih et al, 2016;Puntillo et al, 2004). One of these studies could only correlate vocalization and pain when accompanied by facial expression (Manfredi et al, 2003).…”

“…An association between pain and vocalization was found in 16 out of 22 studies. Four out of five studies on crying found an association with pain (Büttner & Finke, 2000;Dale, 1989;Maitre et al, 2017;Rossato & Angelo, 1999;Warnock, 2003). A total of six studies did not find an association between vocalization and pain, three of which investigated sighing and pain (Robbins, Mehl, Holleran, & Kasle, 2011;Shega et al, 2008;Waters et al, 2008) and one investigated verbalization and pain (Stanford, Chambers, Craig, McGrath, & Cassidy, 2005).…”

“…On the NOS scale, they were awarded five and six stars; however, they only investigated one type of vocalization, i.e. verbalization and crying, respectively (Maitre et al, 2017;Stanford et al, 2005).…”