Pathophysiology
Clinical meaning
Neonates are fully capable of perceiving pain, and research demonstrates that repeated painful experiences in the neonatal period can cause lasting alterations in pain processing, stress responses, and neurodevelopment. This understanding has transformed neonatal care from the outdated belief that neonates do not experience pain to current evidence-based practice requiring systematic pain assessment and management for every neonate. Pain transmission in the neonate involves the same basic neuroanatomical pathways as in adults but with important developmental differences. Nociceptors (free nerve endings that detect painful stimuli) are present and functional throughout the body by 20 weeks gestation. A-delta fibers (which transmit sharp, localized pain) and C-fibers (which transmit dull, diffuse pain) carry nociceptive signals from the periphery to the dorsal horn of the spinal cord. In the dorsal horn, substance P and glutamate are released, transmitting the pain signal to ascending pathways that project to the thalamus and somatosensory cortex. Critically, neonates have an ENHANCED pain response compared to older children and adults due to several developmental factors. First, descending inhibitory pathways from the brainstem that normally modulate and dampen pain...