Long-term Effects of Pain in Infants
Pain in infants has been known to induce significant long-term behavioral and physiological reactions in infants, including those born prematurely. Infants can experience pain that can occur from teething, circumcision, and vaccine shots, among others. Infants can experience pain in different health circumstances such as illness or accidents. Pain is a signal that is sent to the brain in case of injury or when feeling sick. However, it is challenging for clinical practitioners to evaluate the magnitude of pain an infant is experiencing, although they can assess vital symptoms such as breathing rate, pulse rate, among others. Notwithstanding, when dealing with infants, medical practitioners should use to least painful procedures to avert the possibility of long-term adverse effects of pain. Untreated pain in infants can cause long-term effects such as hypersensitivity to pain, increased pain and sensitivity, as well as affect multiple aspects of development in preterm babies.
Long-lasting hypersensitivity to pain has revealed different characteristics of the development of neuronal circuitry that occur due to enhanced pain and sensory responsiveness in very young infants. Pain can manipulate touch-sensitive nerves that evoke the dorsal horn activity (Benoit et al., 2017). The dorsal horn transmits pain signals in the C-fibers located in the spinal cord. In infants, the pain receptive area is larger in size compared to adults in the first three weeks from birth. Eriksson and Campbell-Yeo (2019) argue that the size of the dorsal horn in the newborn has proportionately more neurons in the spinal cord, which amplify the pain signal sent to the brain. Pain from injury at an early age can have profound adverse effects on the peripheral and central neuronal circuits. However, responses to severe pain begin to emerge in the second postnatal week and do not resemble those of adults until after three weeks. Long-lasting hypersensitivity increases due to the lengthened exposure to painful procedures. Hypersensitivity to pain can cause general fear of pain in infants and prolonged response to medication. The body develops neurons that increase response to stimuli. Altogether, these factors contribute to the processing of somatosensory signals that vary in infants compared to mature humans.
Increased pain in tissue from early age experiences body pain results in the enhancement of the somatosensory reflex in infants. According to Moultrie, Goksan, Poorun, and Slater (2016), when a group of infants was treated regularly with typical anesthesia, the infants were capable of increasing sensitivity to pain and mount inflammatory responses with persistent hyperalgesia. Consequently, such a response can be ameliorated by the application of local anesthesia. In a longitudinal study by Eriksson and Campbell-Yeo (2019), tissue injury in infants can cause long-lasting somatosensory sequelae. Moreover, a mechanically-induced flexion reflex to pain on the foot increased with age in infants. Hence, infants with substantial leg injury had no correlation with increased age-related pain. Heightened sensitivity to the contralateral side and hypersensitivity on the affected side of the abdomen was evident in infants born with unilateral hydronephrosis. Notably, in comparison to infants, the normal increase in abdominal reflex to pain was not observed in infants with unilateral hydronephrosis. This suggests that pain in infants can alter spinal cord changes as opposed to local impact.
Pain in infants can affect multiple factors of development in preterm babies. Preterm infants are exposed to surgical, procedural, and post-surgical pain due to their congenital anomalies and life-threatening conditions. Consequently, the greatest impact of pain is likely to occur in preterm babies, which affects multiple aspects of development such as the brain and neurodevelopment. Field (2017) asserts that pain in infants alters the development of the pain system. Pain associated with tissue injury in infantry can cause the wide activation of highly variable elements in the nervous and peripheral systems. As birth weight decreases in infants, more invasive procedures are used which can affect how the infant’s body perceives pain (Goksan, Poorun, & Slater, 2016). Changes in the peripheral system cause an effect on the crucial role in the maintenance and survival of primary afferent neurons. Consequently, the cutaneous fibers are regulated by the release of the nerve growth factor and the brain-derived neurotrophic elements. Thus, the pain increases the development of the nerve growth factors in infants before decreasing in adulthood.
Pain in infants can cause changes in the spinal pain sensory system. During growth, thickly myelinated AB fibers begin to penetrate the dorsal horn with central terminals C fibers. The fibers form connections with deep neurons in the developing cord, which extends to the superficial neurons in the gelatinase substantially (Walker, 2019). The unique superficial terminals from the AB fibers disappear after the synaptogenesis between C-fiber terminals and the substantial gelatinase neurons. Therefore, this explains the similar patterns of neuronal activation noted by “c-fos” expression due to the high-velocity AB axons transmitting noxious and tactile impulses (Eriksson & Campbell-Yeo, 2019). In the immature spinal cord, the connections between the dorsal horn and the synaptic neurons cause prolonged excitement after repetitive or single stimuli. Consequently, this leads to the temporal summation of pain signals associated with background activity and subsequent stimuli. Spinal changes can impair the growth of the neuron-sensory system in infants leading to far-reaching developmental implications. Therefore, pain can cause changes in the spinal cord pain system that prolongs excitement.
The possible long-term implications associated with pain in infants are less well studied. However, preterm infants experience more painful procedures than full-term babies. Additionally, preterm babies with the lowest weight experience far more reaching consequences of pain due to numerous painful medical procedures. Literature from various scholars suggests that no analysis exists related to painful experiences per se. Physiologic research indicates that early pain experiences in infants have more than immediate consequences. Pain in infants as a result of different circumstances can lead to increased infections, a frail immune system, and a prolonged wound healing process. In the future, there is a need to conduct more research on the long-term effects of pain in infants, and the possible interventions that can be implemented accordingly to reduce pain. Arguably, pain in infants results in increased pain sensitivity, although the infants may not preserve the consciousness of the painful events in life. Due to the long-term effects pain has on infants, painful procedures should be avoided where possible. Medical procedures that cause pain in infants should be assessed carefully before implementation to avoid the long-term adverse effects of pain. Where possible, dealing with pain in infants from the onset requires adequate pain management procedures that can help reduce the long-term effects of pain. It is the role of the physician to assess the mood of the infants or use scales for measuring pain while advocating for pain-minimizing procedures that increase comfort measures.
Benoit, B., Martin‐Misener, R., Newman, A., Latimer, M., & Campbell‐Yeo, M. (2017). Neurophysiological assessment of acute pain in infants: a scoping review of research methods. Acta Paediatrica, 106(7), 1053-1066.
Eriksson, M., & Campbell-Yeo, M. (2019, April). Assessment of pain in newborn infants. In Seminars in Fetal and Neonatal Medicine. WB Saunders.
Field, T. (2017). Preterm newborn pain research review. Infant Behavior and Development, 49, 141-150.
Moultrie, F., Goksan, S., Poorun, R., & Slater, R. (2016). Pain in neonates and infants. An Introduction to Pain and its Relation to Nervous System Disorders, 283.
Walker, S. M. (2019, April). Long-term effects of neonatal pain. In Seminars in Fetal and Neonatal Medicine. WB Saunders.