Cortical pain responses in human infants - towards a rational analgesic strategy

Babies in hospital, especially those that are born very premature, are regularly exposed to painful procedures as part of their routine medical treatment. However, infants are unable to say whether or not it hurts and other methods are needed to assess the amount of pain they feel. This study offers an insight into how best to manage pain relief in very young infants. We aim to assess the way in which babies respond to painful stimulation and other sensations while they are having their routine blood tests. Non painful sensations, such as light touch with nylon hairs and vibration will also be used. Brain activity will be monitored with electrodes gently placed on the infant’s scalp to see whether any waves arise in specific parts of the brain following a painful and non-painful stimulus. We will test how these responses change with age, whether they are affected by the number of painful procedures a baby has experienced, and most importantly whether they are reduced by current pain relieving medicines.

Infants in intensive care necessarily undergo repeated invasive procedures and yet treatment for their pain remains sporadic and suboptimal. Clinical trials of analgesics in preterm infants are urgently needed but cannot be undertaken without direct, objective and quantitative measures of pain responses in this population. In this study we will record cortical somatosensory potentials in preterm infants evoked by noxious (heel lance) and non-noxious (touch, electrical and vibration) stimulation. We will test whether (i) noxious stimulation evokes neural activity in the human infant somatosensory cortex that can be measured using neurophysiological methods (ii) infant cortical responses to noxious stimulation increase with postmenstrual age (iii) repeated invasive intensive care procedures influence the cortical response to noxious stimulation (iv) cortical and brainstem/spinal reflex responses to noxious stimulation are differentially regulated and not predictive of one another (v) existing analgesic regimes using i.v. morphine and oral sucrose reduce cortical responses to noxious stimulation. The data will provide the first objective measure of infant cortical pain processing and test the effectiveness of putative analgesic agents in preterm infants. The study can be used as a basis for larger studies and trials to test new analgesic strategies.