Pain Research in Children with Cerebral Palsy
Pain in children is a relatively new area of research with historical roots dating only to the early 1970s (Hester, 1993). Inquiry focused on pain in children with developmental or physical disabilities such as CP is severely lacking. Only recently has the secondary condition of pain been researched in adults with cerebral palsy. Results suggest pain is common in this population, with 67%-84% of participants reporting chronic pain (Engel, Jensen, Hoffman, & Kartin, 2003; Schwartz et al., 1999; Turk, Geremski, Rosenbaum, & Weber, 1997) and 18%-56% noting daily pain occurrences (Andersson & Mattsson, 2001; Engel et al.; Schwartz et al.).
Following structured interviews of 20 children with CP, Petrina (2001) noted 70% reported experiencing bothersome pain lasting 1 hour or greater per episode, and 64% described pain as being a problem. Chalkiadis (2001) described children with CP or spasticity as the largest group of patients referred to a pediatric multidisciplinary pain clinic in Australia. Their complaints included hip and/or back pain associated with spasticity, subluxation, and osteoarthritis. Sleep disturbance also was reported to be a recurrent issue in this population and often dissipated when pain specifically was addressed. Hadden and von Baeyer (2002) noted 67% of parents reported observing pain behaviors in their children with CP within the past month. Assisted stretching was the most common activity of daily living, range of motion the most frequent therapeutic intervention, and needle injection the most identified medical procedure to cause pain (93%, 58%, and 40%, respectively, of those reporting pain). Kibele (1989) also reported pain with stretching was common. Liptak et al. (2001) found children with moderate to severe CP reported significantly higher pain severity compared to national norms using the Child Health Questionnaire (CHQ) as a standardized interview tool (Landgraf, Abetz, & Ware, 1996). These children also scored below the mean in general health, physical functioning, and effect on parents. Using a population-based sample of 408 children with CP, Kennes and associates (2002) demonstrated that severity of CP using the GMFCS did not directly relate to the experience of pain as reported by parents on the CHQ.
Research concerning pain in children with CP has emphasized parent or healthcare professional report, which may or may not accurately reflect the child's experience. Studies that include a component of pain prevalence, assessment, or management in children with CP are focused on outcomes of a surgical procedure, pharmacological intervention, rehabilitative activities, or health-related quality of life (QOL) inquiry. Table 1 lists common experiences that may contribute to pain as a secondary condition in children with CP. A discussion concerning these experiences as well as suggestions for future research follows.
A variety of surgical procedures may be performed on children with CP to improve function, decrease muscle tone, or correct deformity. These procedures include but are not limited to selective dorsal rhizotomy, soft tissue releases, tendon lengthening, capsulotomy, fasciotomy, osteotomy, tenotomy, and spinal fusion (Dzienkowski et al., 1996; Nolan et al., 2000). There is extensive literature on most of these procedures, and overall, successful outcomes have been shown in improved motor function, range of motion, decreased muscle tone and even health-related QOL. If spasticity is a problem, intrathecal baclofen may be administered following surgical implantation of a pump (Van Schaeybroeck et al., 2000). This procedure has been shown to be effective for the treatment of spasticity (Albright, Barron, Fasick, Polinko, & Janosky 1993; Van Schaeybroeck et al., 2000), but it is invasive and little is known about its effects on pain. Significant gastrointestinal or nutritional problems may also necessitate surgical procedures, such as a fundoplication and/or placement of a gastrostomy tube (Nolan et al.). These procedures are intended to improve nutritional support, but may be accompanied by side effects such as infection and gastroesophageal reflux with subsequent pain or discomfort.
Following surgery, structured positioning and rehabilitative protocols are often implemented including splinting, orthotics, and intensive range of motion or functional activities. Furthermore, postoperative problems such as nausea, muscle spasm, constipation, and skin breakdown due to immobility may occur (Nolan et al., 2000). A child may experience pain or discomfort related not only to the surgical procedure or site, but also as a result of associated healing and remobilization interventions. Several research studies and review articles have addressed pharmacological interventions for postoperative pain in children with CP. Studies concerning pain management following selective dorsal rhizotomy have found that the use of pharmacological agents such as morphine (continuous infusion, patient-controlled analgesia, or epidural) and/or a benzodiazepine infusion were effective in treating postoperative pain and muscle spasticity (Geiduschek et al., 1994; Sparkes, Klein, Duhaime, & Mickle, 1989). Despite the attention given to postoperative pain management in children with CP, little has been done to examine nonpharmacological interventions or explore the experience of procedural pain from the child's perspective.
Spasticity is a frequent problem for many children with CP (Roscigno, 2002). Hypertonicity can lead to contractures, deformity, and functional impairment (Roscigno). Aside from oral and rectal administration of pharmacologic agents, intramuscular injections of botulinum toxin type A (also known as Botox or Dysport) have proven to be effective in reducing muscle spasms and pain while improving functional status in both adults and children with CP (Graham, 2000; Hart, 2000; Kirshner, Berweck, Mall, Kornthenberg, & Heinen, 2001). These injections produce a dose-dependent chemodenervation of muscle. The relaxation effect typically lasts for approximately 3-6 months (Graham; Hart). Irritation or pain at the injection site has been shown to be the most common side effect (Forssberg & Tedroff, 1997; Hart), lasting up to 1-2 days. This type of procedural discomfort or pain might also be common following other medical interventions frequently experienced by a child with CP such as medication injections, blood draws, nasogastric tube placement, enemas, and administrations of anesthesia. In fact, Hadden and von Balyer (2002) identified needle injection as the most frequently reported painful medical or nursing procedure by parents of children with CP with a mean intensity of 3.1 on a 0-5 scale (0 = no pain; 5 = worst pain possible). The need for repeating these interventions on a regular basis may result in chronic, procedure-related anxiety or distress and emotional strain (McGrath, 1990).
In a study of 58 children with CP, Del Giudice and colleagues (1999) found that 92% of the children had clinically significant gastrointestinal symptoms including abdominal pain (32%). Gastroesophageal reflux (GER) is a common problem in children with CP, especially those with limited mobility, poor control or coordination of the orofacial musculature, and esophageal dysmotility (Nolan et al., 2000; Samson-Fang, Butler, & O'Donnell, 2003). Surgical procedures to enhance or support nutritional intake, such as gastrostomies and fundoplications, are reported to be the second most frequent surgeries experienced by children with CP (Nolan et al.). Impaired oropharyngeal function and GER may contribute to extended mealtimes, fatigue with eating, malnutrition, and the incidence of aspiration pneumonia (Darwish, 1999; Samson-Fang et al.). Theoretically, pain may be associated with each of these conditions due to gastrointestinal discomfort, delayed healing responses, respiratory difficulties, procedure-related pain or discomfort, and possible surgical intervention, resulting in postoperative pain.
Immobility, spasticity, and congenital deformity may contribute to painful orthopedic conditions. Hodgkinson and associates (2001) reported that 47% of their sample of nonambulatory adolescents and young adults with CP reported hip pain. Hip subluxation and dislocation is a frequent problem associated with CP, especially in children with severe spastic quadriplegia who are nonambulatory (Bleck, 1987). Bagg, Farber, and Miller (1993) demonstrated that dislocated hips caused degenerative arthritis, pain, and decreased movement. Other orthopedic deformities associated with CP are cephalad displacement of the patella, equines of the ankle, valgus deformities of the ankle, varus and valgus deformities of the foot, radial subluxation or dislocation, cartilage degeneration, scoliosis, pelvic obliquity, kyphosis, lordosis, and contractures (Bleck, 1987). These deformities may lead to chronic knee, ankle, foot, upper extremity, back, and neck pain due in part to biomechanical abnormalities, sustained muscle contraction around these joints, poor positioning, skin breakdown, and impaired mobility. A study by Tenuta, Shelton, and Miller (1993) found that 41% of adults with CP who had undergone a triple arthrodesis surgery as a child continued to have pain in adulthood. In addition, osteoarthritis and osteoporosis may be present and produce pain. This pain often begins early in childhood and worsens with age (Bleck). Long and Hart (1995) identified hip, knee, and foot pain as common in youth with CP and attributed these pain problems to multiple factors such as congenital dislocation, joint stress related to hypertonic muscles, and overuse. These potentially painful orthopedic conditions require careful attention, assessment, and monitoring in order to recommend the best course for appropriate management.
Lesions of the motor areas in the brain in association with injury or deformity of the descending motor pathways (corticospinal tracts) result in spasticity in the child with CP (Kandel, Schwartz, & Jessell, 2000). Spasticity is characterized by increased tone, hyperreflexia, clonus, and resistance to stretching (Kandel et al.; Roscigno, 2002). Furthermore, spasticity can contribute to contractures and musculoskeletal deformities due to reduced longitudinal muscle growth (Graham, 2000). Although the mechanism of spasticity-related pain is not well understood, pain may be associated with spasticity as well as the resulting impairment and deformity. Roscigno (2002) provides a comprehensive review of the most frequent pharmacological interventions used to treat spasticity-related pain and a brief overview of surgical interventions for spasticity management in children with CP. Inconsistency in muscle tone, impaired purposeful movement, and other motor aberrations such as twisting/writhing movements and tremors may be the result of injury or abnormality in the basal ganglia. This type of motor impairment may cause upper extremity orthopedic deformities as well as hip dislocations that may be painful (Dzienkowski et al., 1996). Pharmacological agents and surgical interventions are used in the care of children with these types of impairments and pain complaints. Rehabilitative interventions such as occupational, physical, and speech therapy are employed to maximize function and comfort.
Children with CP often have a limited range of available functional movement and may develop overuse syndromes, nerve entrapments, radiculopathies, and myelopathies. Gajdosik and Cicirello (2001) summarized the contributing factors and potential for pain as well as loss of function related to these secondary conditions.
Chronic shortening and misalignment of muscles as a result of spasticity or restricted movement may lead to contractures, another potentially painful problem (Nehring, 2000). Although range of motion, positioning devices, and splints/orthotics may help to prevent or minimize contractures, these interventions may cause pain or discomfort at least in the short term (Kibele, 1989). This relationship between well-intended, necessary interventions and the adjunct contribution to pain is also true of many rehabilitative activities performed with children with CP.
Children with CP regularly participate in rehabilitative therapies such as occupational, physical, and speech therapy with the intensity and frequency individualized to meet the needs and concerns of the child. Therapeutic interventions are range-of-motion activities, home exercise programs, strengthening, electrical stimulation, functional mobility training, participation in activities of daily living, splinting and orthotic fabrication and follow-up, serial casting, training for use of adaptive equipment, and utilization of standing frames and other positioning devices. Although these activities are intended to improve functional or physical status and minimize disability-related pain, many of these activities may be encumbered by pain or prompt a painful experience in a child with CP. Kibele (1989) reported that one of the most salient negative memories of childhood in adults with CP was the pain related to stretching and bracing in physical therapy. Hadden and von Baeyer (2002) noted parents of children with CP identified assisted stretching as the most frequent activity of daily living observed to be painful (93% of those reporting pain). Furthermore, range-of-motion therapy was noted as the most common, painful activity (58%) with an intensity higher than that of other activities (mean of 2.3 on a 0-5 scale). Many of the rehabilitative interventions such as range-of-motion therapy, positioning devices, and wearing of splints or orthotics are done on a daily if not continuous basis. Children with CP engaged in ongoing rehabilitative efforts may display increasing anxiety, fear, frustration, withdrawal, or distress about these interventions given the potential for associated pain (McGrath, 1990; Turnquist & Engel, 1994). These may result in depression, poor coping, decreased participation in treatment, and limited therapeutic goal attainment (Kibele & Flint, 1990; Tyler, 1990). However, in their study, Miller, Johann-Murphy, and Cate (1997) demonstrated that pain and anxiety in children with CP decreased over time during rehabilitation following selective posterior rhizotomy. The authors noted that special considerations for pain assessment and management were observed, perhaps supporting this decrease. This may not always occur in rehabilitation given therapists' limited knowledge and awareness concerning pain (Turnquist & Engel, 1994).
Two studies, one a survey of pediatric occupational therapists and the other a survey of physical therapists working in orthopedics, revealed that therapists receive inadequate education in their degree programs concerning pain theory and management, which directly affects their knowledge of appropriate pain assessments and interventions (Turnquist & Engel, 1994; Wolff, Michel, Krebs, & Watts, 1991). Enhanced education and clinical focus, in addition to increased knowledge about children's pain experiences, might prove beneficial in minimizing the experience of pain for children with chronic conditions such as CP.
J Neurosci Nurs. 2004;36(5) © 2004 American Association of Neuroscience Nurses
Cite this: Pain in Children With Cerebral Palsy: A Review - Medscape - Oct 01, 2004.