Beyond Acute Pain: Understanding Pain that Persists in Infancy

The aims of this topical review are to present the current challenges in defining chronic pain in infants, to summarize evidence from animal and human infant studies regarding the biological processes necessary for chronic pain signaling and to present observational/experiential evidence from clinical experts. A literature search of four databases, CINAHL, EMBASE, PsycINFO, and MEDLINE, was conducted along with hand searches of reference lists. Evidence from animal studies suggest that important biological mechanisms, such as the availability of key neurotransmitters needed for maintenance of chronic pain, may be immature or absent in the developing neonate. In some cases, human infants may be significantly less likely to develop chronic pain. However, evidence also points to altered pain perception, such as allodynia and hyperalgesia, with significant and/or pain insults. Moreover, clinicians and parents in pediatric intensive care settings, describe groups of infants with altered behavioral responses to repeated or prolonged painful stimuli, but agreement as to a working definition of chronic pain in infancy remains elusive. Our understanding of infant chronic pain is still in rudimentary stages. However, pain management cannot wait until a clear taxonomy is delineated for the infant period. Careful and methodical approaches to longer-term pain management are required.