Acute and chronic pain in children

Age-dependent plasticity in endocannabinoid modulation of pain processing through postnatal development

Supplemental Digital Content is Available in the Text.

Endocannabinoid signalling within brainstem centres that control top-down pain control changes significantly in early life in both rodents and humans.

Significant age- and experience-dependent remodelling of spinal and supraspinal neural networks occur, resulting in altered pain responses in early life. In adults, endogenous opioid peptide and endocannabinoid (ECs) pain control systems exist which modify pain responses, but the role they play in acute responses to pain and postnatal neurodevelopment is unknown. Here, we have studied the changing role of the ECs in the brainstem nuclei essential for the control of nociception from birth to adulthood in both rats and humans. Using in vivo electrophysiology, we show that substantial functional changes occur in the effect of microinjection of ECs receptor agonists and antagonists in the periaqueductal grey (PAG) and rostroventral medulla (RVM), both of which play central roles in the supraspinal control of pain and the maintenance of chronic pain states in adulthood. We show that in immature PAG and RVM, the orphan receptor, GPR55, is able to mediate profound analgesia which is absent in adults. We show that tissue levels of endocannabinoid neurotransmitters, anandamide and 2-arachidonoylglycerol, within the PAG and RVM are developmentally regulated (using mass spectrometry). The expression patterns and levels of ECs enzymes and receptors were assessed using quantitative PCR and immunohistochemistry. In human brainstem, we show age-related alterations in the expression of key enzymes and receptors involved in ECs function using PCR and in situ hybridisation. These data reveal that significant changes on ECs that to this point have been unknown and which shed new light into the complex neurochemical changes that permit normal, mature responses to pain.

[Pain syndrome of the musculoskeletal system in children and adolescents]

Chronic pain syndromes in children and adolescents are defined as continuous or recurrent pain without an underlying causative diagnosis and lasting for more than 3 months. It is estimated that every fourth child in Germany suffers from chronic pain with every twentieth suffering from extreme recurrent pain. The incidence of chronic pain in children and adolescents is increasing with headache, abdominal pain and musculoskeletal pain being the most frequent. The quality of life declines not only due to the pain but to relieving postural and psychological factors, such as fear and sadness. School attendance, social activities and hobbies are mostly affected. This review summarizes the background of chronic pain syndromes and introduces a multimodal therapeutic approach.

Beyond Acute Pain: Understanding Chronic Pain in Infancy

This topical review presents the current challenges in defining chronic pain in infants, summarizes evidence from animal and human infant studies regarding the biological processes necessary for chronic pain signaling, and presents 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 neurophysiological 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 injury. Moreover, clinicians and parents in pediatric intensive care settings describe groups of infants with altered behavioral responses to repeated or prolonged painful stimuli, yet agreement on a working definition of chronic pain in infancy remains elusive. While our understanding of infant chronic pain is still in the rudimentary stages, a promising avenue for the future assessment of chronic pain in infancy would be to develop a clinical tool that uses both neurophysiological approaches and clinical perceptions already presented in the literature.