Swiggum, Mary PT, PCS; Hamilton, Merry Lynne PT, PhD; Gleeson, Peggy PT, PhD; Roddey, Toni PT, PhD
Pain is a frequent if not daily experience for many children with cerebral palsy (CP).1–4 Families of children with CP identify bodily pain and pain associated with physical therapy (PT) as deterrents to high quality of life.5 Despite the growing awareness of pain in children with CP and its adverse effects, there is a paucity of physical therapist–led research investigating pain in this population. Most research has been completed by other healthcare professionals, and few recommendations have been incorporated into PT practice. This article addresses this by reviewing the available pain assessment tools for children with CP and the application of psychosocial pain management techniques to pediatric PT interventions.
DEFINITION OF PAIN
The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual and potential tissue damage.”6 The Guide to Physical Therapy Practice defines pain as “a disturbed sensation that causes suffering or distress.”7 Apparent in both definitions, pain is a subjective experience. Prolonged or repeated exposure to pain can alter responses to future painful stimuli (hyperalgesia) and even to usually nonpainful stimuli (allodynia).8–11 Additional factors that may influence the experience of a painful event include chronological age, gender, cognitive and emotional development, coping skills, culture, and conditions surrounding the event. Consequently, a child's response to stressful and painful events is not stable and may be modified by knowledgeable adults.
ETIOLOGY OF PAIN IN CHILDREN WITH CP
There are many potential contributors to pain in children with CP. McKearnan et al12 classified these causative agents into the following categories: surgical, procedural, gastrointestinal, orthopedic, neuromuscular, and rehabilitative. Depending on how pain is defined, psychological mechanisms may also contribute to the pain experience. This review does not focus on the surgical and procedural causes of pain because these have received considerable attention and are not specific to children with CP. Classifications by McKearnan et al of gastrointestinal, orthopedic, neuromuscular, and rehabilitative causes of pain are reviewed along with the role of psychological mechanisms.
Common gastrointestinal problems associated with pain in children with CP include dysphagia, esophagitis, gastritis, gastroesophageal reflux, gastrointestinal tube feeding, constipation, and enteric ulcers.13 Del Giudice et al14 reported the incidence of gastroesophageal reflux in CP as 32% in a sample of 58 children, but 92% of those studied had clinically significant gastrointestinal pain. Gastrointestinal dysfunction may result in behavioral problems at mealtimes; distress upon lying down after a meal or at night; excessive hand mouthing; excessive drooling; and head and trunk posturing into extreme flexion or extension.
Numerous orthopedic deformities and biomechanical abnormalities associated with CP can be a source of chronic pain.15,16 It is suggested that sustained muscle contraction around joints and poor postural alignment can lead to the early onset of degenerative arthritis.17,18 Orthopedic deformities that have been correlated with pain include hip subluxation and dislocation, patella alta, equinus, valgus deformities of the knee and ankle, radial dislocation or subluxation, cartilage degeneration, scoliosis, pelvic obliquity, kyphosis, lordosis, and contractures.16,19,20
Although the mechanism of spasticity-related pain is not well understood, spasticity plays an important role in at least some chronic pain. In addition to the muscle and joint problems that arise from spasticity, spasticity may affect essentially every system in the body (ie, gastrointestinal, respiratory, and circulatory). In addition to spasticity, other etiologies include nerve entrapments, radiculopathies, and myelopathies.21
Kibele22 reported that one of the most salient negative memories of childhood in adults with CP was the pain related to PT interventions of stretching and bracing. A survey by Hadden et al23 of parents revealed that the activity most frequently identified as painful and greatest in pain intensity for children with CP was assisted stretching. Other reported painful activities included independent standing, assisted walking, assisted sitting, and donning splints. Since then, Hadden et al have identified PT intervention as a convenient setting to further study pain in children with CP. Using the Non-communicating Children's Checklist, Postoperative Version to evaluate pain responses, they demonstrated a significant increase in pain behaviors during stretching activities.24
Others confirm the findings of Hadden et al. McKearnan25 surveyed 95 youth with developmental disabilities aged 8 to 20 years. Fifty-eight percent reported pain during physical or occupational therapy. Fifty-three percent reported pain during a therapeutic home program. Stretching was the most frequently mentioned painful activity.
The following electronic databases were searched from January 1998 to June 2008: Cochrane Central Register of Controlled Trials, MEDLINE, CINAHL, PsychINFO, ERIC, Proquest Nursing and Allied Health Source, and WORLDCAT Dissertations. Search terms included combinations of pain, children, CP, PT, psychosocial pain management, nonpharmaceutical pain management, pain assessment, and pain tools. Additional hand searches were performed as indicated. Articles that were directly related to PT intervention for children with CP were included. Articles related to pediatric pain assessment and management and pediatric PT were included if application to children with CP was discerned by the primary author.
Several categories of pain assessment tools exist, including self-report, physiological pain, behavioral pain, and distress measures.
Self-report measures can be verbal, such as structured interviews, questionnaires, self-rating scales, and pain adjective descriptors, or nonverbal behaviors, such as facial expression scales and drawings. Aspects of pain that may be assessed through self-report include location, intensity, duration and quality, affective reactions, situational factors that increase pain, and pain-related disability. Numerous scales exist. An article by O'Rourke26 provides a chart outlining uses for the individual tools and their psychometric properties.
Self-report has been identified as the gold standard in pain assessment. However, von Baeyer27 identified limitations of self-report measures in children. These include (1) the requirement of sufficient cognitive and language development; (2) lack of understanding may lead children to construct an answer; (3) children younger than 5 years tend to treat scales as dichotomous rather than graded and choose only the extremes; and (4) children's reports of pain may be affected by their perception of the consequences of the rating.
Accurate pain assessment requires careful consideration of the child, the nature of the pain, and the availability and appropriateness of various pain scales (Table 1). The administration of a pain scale requires careful planning as well (Table 2). Adhering to the recommendations in Table 2 may help ensure valid results. However, the use of self-report measures in children with CP during PT procedures is further limited by insufficient evidence regarding the reliability and validity of their use in this population.
Commonly used assessment tools that rely on behavioral measures include the Child Facial Coding System28; the Children's Hospital of Eastern Ontario Pain Scale29; and the Face, Legs, Activity, Cry, and Consolability Behavioral Pain Assessment Scale.30,31 Behaviors associated with pain in children are listed in Table 3.
Recently, researchers have been developing tools in consultation with caregivers specifically for use in children with CP, such as the Non-communicating Children's Pain Checklist, Postoperative Version,32,33 the Individualized Numerical Rating Scale (INRS),34 and the Pediatric Pain Profile (PPP).35 The INRS and the PPP are envisioned as parent-administered scales (Table 4).
Physiological measures, such as heart rate, vagal tone, blood pressure, oxygen saturation, palmar sweating, and neuroendocrine response, may be used to rate pain responses. Challenges associated with interpreting these measures in isolation include the following: (1) physiological responses to various types of stress are similar; (2) physiological responses to long-term pain seem to habituate; (3) gestational age, medications, overall health, and environmental factors may influence response (Table 5). Additionally, according to Breau et al36 the majority of researchers suggest that physiological responses to pain in children with neurological impairment may differ from those expressed by typically developing children.
PSYCHOSOCIAL PAIN MANAGEMENT TECHNIQUES
Psychosocial pain management techniques may be divided into cognitive-behavioral methods and social environmental interventions. Techniques vary depending on the age and developmental functioning of the child due to cognitive, emotional, and communicative differences. The Appendix describes some of the most frequently studied pediatric psychosocial pain management techniques. Most of the research on psychosocial pain reduction techniques for children has been related to acute or procedural pain, such as needle injections, suctioning, dental procedures, and postoperative care. Some research, however, has considered chronic conditions such as headaches and abdominal pain (Table 6). This search of the literature revealed only 2 studies focused on children with CP.
Cognitive-behavioral methods promote the development and application of coping skills and knowledge of the relationships of thoughts and behaviors to pain experiences. Strong evidence supporting the use of these interventions to address chronic headache, abdominal pain, and needle-related procedural pain in typically developing children was found in an analysis of 3 Cochrane reviews.37–39 Attention-shifting measures, such as distraction, have received considerable attention and support as techniques to decrease both behavioral and self-reported measures of pain and distress in children.42–44 The literature supports the effectiveness of distraction in reducing pain, provided the age and interests of the child are considered in addition to the characteristics of the healthcare environment. Memory alteration is another cognitive-behavioral strategy to consider with young children. Emerging research suggests that memories of procedures can be edited making subsequent procedures less painful.45 Children may introduce false information into a retrospective account of an event. A knowledgeable adult can alter the way in which a child experiences and/or remembers pain by shaping the event as it occurs or afterward. Essentially, a child's memory of the painful event can be “reframed” by the adult.
No studies that explored the use of these strategies to decrease pain and promote coping in children with CP during PT interventions were found.
Social Environmental Interventions.
The search revealed 1 study that explored the role of the social environment on the responses of children with CP to potentially painful stretching. Miller et al40,41 investigated the influence of physical therapists' behavior and the passage of time on the level of distress and coping in children with CP undergoing rehabilitation after selective dorsal rhizotomies. The rehabilitation included sessions of stretching. The Child Adult Medical Procedure Interaction Scale was used to code the behavioral interactions. A positive relationship was observed between therapist coping-promoting behavior and coping behavior in the children (r = 0.72). Commands to use coping and nonprocedural talk were helpful. Similarly, there was a positive relationship between distress-promoting physical therapist behavior and distress in the children (r = 0.61). Criticism and reassurance were associated with increased levels of distress. Overall, the children's distress during therapy sessions decreased over time.
Children with CP are at increased risk for pain compared with the general population due to the frequency of occurrence of gastric, neuromuscular, and orthopedic problems as well as surgical and procedural interventions. These risk factors may compound the pain that is experienced during PT-recommended procedures. Although numerous pain tools have been developed for use in hospital environments to assess children's pain and distress responses to acute and procedural interventions, few have been developed to assess responses to less invasive procedures such PT interventions. The use of these assessment tools and their validity and reliability during real-time PT interventions have not been explored. Psychosocial pain management techniques are effective in reducing pain and distress in children during procedural interventions. These techniques have the potential to decrease stress for the caregivers as well. There is emerging evidence that these techniques may assist children with CP in coping with pain and distress during postsurgical PT interventions. A gap appears to exist between the assessment and management of pain in children developing typically and those with CP. Physical therapists can assist in closing this gap by addressing issues related to practice and research.
IMPLICATIONS FOR PT PRACTICE, EDUCATION, AND RESEARCH
Pediatric physical therapists should examine their current knowledge and practice patterns regarding behavioral indicators of pain in children with CP. Interventions that are contributing to distress and pain must be openly acknowledged, and the evidence for their use be analyzed. Evaluative and discriminative pain and distress assessment tools should be incorporated into PT practice, although tool reliability and validity needs to be addressed for this population. Parent-administered pain assessment tools, such as the INRS and the PPP, should be encouraged. The literature supports the use of psychosocial intervention, specifically, age-appropriate distraction and coping strategies, to prevent and reduce the experience of pain in children. These techniques should be incorporated into PT treatment interventions and home programs. Physical therapist responses that may contribute to distress and maladaptive pain coping skills should be avoided, including the use of reassurance, apologies, criticism, and encouraging pain-contingent rest. Lifelong management of pain needs to be considered early as a child's experiences with the healthcare environment can affect later health behaviors. Families should be educated in relevant models of disease and pain management. Families and children should be encouraged to adopt regular exercise routines and exposure to movement despite pain.
Research on the etiology, assessment, and management of pain in children with CP is limited. Most of the research on pain assessment and management in children has been performed during one-time procedural interventions, such as needle injection. Little is known about pain responses to PT interventions or how those responses may be evaluated and modified by psychosocial or physical interventions. Areas for research include (1) comparison of caregivers' and children's perceptions of pain with physical therapists' perceptions of pain for children with CP; (2) identification of physical therapists' characteristics, experiences, or beliefs that influence awareness of and responses to pain in children with CP; (3) investigation of assessment tools and interventions used by physical therapists to assess and manage pain in children with CP; and (4) investigation of the psychometric properties of pain assessment tools used for children with CP during PT procedures.
Pediatric therapists are in frequent and intimate contact with young children with CP and their families and are in a unique position to assess and manage pain in this population. Therapists must acknowledge the pain that children experience and its effect on cooperation and motivation during therapy sessions and home programs, and understand the effect of pain on family functioning, future pain responses, and the child's quality of life. Research on interventions to reduce pain in this population, including physical and psychosocial supports, is needed as is the development of protocols to guide therapists during potentially painful procedures so that evidenced-based, cost-effective, and compassionate PT can be provided.
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