Functional Neuroimaging of Breastfeeding Analgesia by Multichannel Near-Infrared Spectroscopy

BACKGROUND: Newborns perceive pain, and several non-pharmacologic analgesic methods have been used during painful procedures. Activation of the neonatal somatosensory cortex, in association with a painful procedure without analgesia, has been demonstrated by two-channel near-infrared spectroscopy (NIRS). OBJECTIVES: To evaluate both cortical and behavioural responses of healthy term newborns to a painful procedure during two non-pharmacologic analgesic interventions, i.e. glucose solution and breastfeeding. METHODS: The effects of glucose and breastfeeding on pain-associated neonatal cortical activity were studied in two groups (n = 30) by multichannel NIRS during a heel prick. Cortical activation was identified by variations in oxygenated haemoglobin. Neonatal pain expression was assessed by a validated scale. RESULTS: No significant variations in cortical activity emerged using glucose solution, whereas breastfed newborns showed widespread cortical activation. Breastfed neonates showed significantly less behavioural pain expression. CONCLUSIONS: Glucose is associated with no significant cortical activation and may interfere with pain-associated response at the cortical level. Conversely, breastfeeding analgesia is associated with generalized cortical activation and may act by multisensory stimulation, possibly overwhelming pain perception.