Pain in Children
How does age influence the perception of the pain experience? We start at the beginning of the age continuum—from infants to children—and examine the role of age as it relates to social and physiologic development, cognitive processing, and coping skills.
In 2012, the American Pain Society Task Force on Pediatric Chronic Pain defined chronic pain as recurrent or persistent pain lasting longer than normal tissue healing time, approximately 3 to 6 months.1 Not long before this, it was believed that very young children did not feel pain. This belief was based on research from the 20th century that argued that for pain to be perceived, the myelination of the nerve pathways must be complete.2 In 1941, research by McGraw stated that because of the incomplete development of the cerebral cortex, children were incapable of any memory before the age of 6 months.3 Based on these findings, it was believed that infants and young children, who cannot articulate what pain feels like, rarely needed analgesic medicine after surgery.
Today, we know that nociceptors are in place from the 20th week of intrauterine life and that the peripheral pathways, although not yet myelinated, are in place before the end of the embryonic period.4,5 Therefore, we now know that all of the neurophysiologic structures involved in processing the pain signal are in place several weeks before birth. In addition, based on recent research, it now is believed that newborns are more vulnerable to pain compared to adults.6-8 Recognition of this has led researchers to observe the behavior of infants and young and nonverbal children to attempt to quantify their pain.
Children can experience a wide variety of painful conditions, such as cancer, arthritis, diabetic neuropathies, complex regional pain syndromes, fibromyalgia, irritable bowel syndrome, and headache, to name a few. For those interested in a more complete discussion on the types of pain in childhood, Schechter et al wrote an excellent chapter.9
Components of Pain
Because of the inconsistent criteria used in assessing pain in children, prevalence numbers vary widely. According to Perquim et al, during childhood the most frequent pain conditions are abdominal, musculoskeletal, and headache pain.10 The best estimate of the incidence of moderate to severe pain in childhood is 5%.11
The central question that needs to be explored is how children experience pain. Recent thinking has identified 3 components involved in childhood pain: the directive, discriminative, and cognitive components.5 According to Marchand, the directive component is transmitted by the C fibers, which represent slow and diffuse pain.12 The discriminative component is transmitted by the A-delta fibers, which are the faster, smaller myelinated fibers. The cognitive component refers to the brain and its capacity to understand the pain experience. The cognitive component is influenced by family, culture, education, and previous painful experiences.12
To better understand how these components interface, Table 1 provides a brief review of the major stages of child development. According to Piaget, the major stages of development are completed by age 14 years.
Chronic Pain in Children
As noted, one of the most frequent type of pain in children is headache, both tension and migraine (Figure 1). It is estimated that 20% of all pain in children is head pain, with migraine frequency increasing with age. Children with recurrent headache tend to be anxious, hypersensitive, and excessive worriers.13 Recurrent headache also appears to run in families, with at least one parent experiencing similar pain during their childhood.7 (See Headaches in Children).
Abdominal pain is the second most frequent type of chronic pain in children. Its incidence varies from 10% to 18%, with it most frequently occurring between the ages of 8 and 10 years. There are several reasons that have been forwarded to explain why this occurs. Children during this age tend to imitate their parents, and if they see significant others reacting to stress in maladaptive ways, they will model similar coping styles. The research suggests that abdominal pain also tends to run in families in which pain is a way of life.13
The third most frequent recurrent pain found in children generally is called limb or growing pain. This type of pain usually occurs between the ages of 8 and 12 years, and it affects about 4% to 15% of the children in this age range. It is difficult to treat because there rarely is any organic cause that can be determined and usually is not associated with any redness or swelling.13
Focus on Family Key
The above research strongly suggests that most of the different types of recurrent pain that children experience are directly related to family influences, both genetic and environmental. When I evaluate a child who has recurrent pain, the inclusion of at least one parent or caregiver is required. If the child is an appropriate candidate for behavioral treatment, the parent is required to sit in and participate. If I teach the child relaxation techniques, the parent also must learn the same techniques. I have found this format useful, because it allows the parent and child to practice together as a family in their own home. This approach also is beneficial because it reduces the pressure on the child as the identified patient and shifts the focus to the family.
Shifting the focus of treatment to the family has gained research support over the past decade. It now is recognized that parents who experience depression and anxiety are more likely to have children with chronic pain.14 The same research group also found that mothers of children with functional abdominal pain were 4.9 times more likely to have a history of depressive disorders and 4.8 times more likely to have a history of anxiety disorders.
This pattern of familial influences on the incidence of pain appears to carry over into the adolescent years. Mothers of adolescents with pain exhibited more symptoms of stress, anxiety, and depression compared to mothers with adolescents who were pain free.15 In addition, in a large population-based study in the Netherlands, maternal symptoms of anxiety during pregnancy predicted increased somatic complaints in the baby at 18 months of age.16 We need to be careful not to over interpret the research, but it suggests that maternal mental health may predict or predispose a child to develop recurrent pain. Early identification of mothers at risk for mental health issues is improving and early intervention is becoming more proactive.