Musculoskeletal Pain Syndromes

Clinical Manifestations

Chronic musculoskeletal pain syndromes involve pain complaints at least 3 mo in duration in the absence of objective abnormalities on physical examination or laboratory screening. Additionally, children and adolescents with musculoskeletal pain syndromes often complain of persistent pain despite previous treatment with nonsteroidal antiinflammatory drugs (NSAIDs) and analgesic agents. The location varies, with pain complaints either localized to a single extremity or more diffuse and involving multiple extremities. The pain may start in a single area of the body before intensifying and radiating to other areas over time. The prevalence of musculoskeletal pain syndromes increases with age and is higher in females, thus rendering adolescent girls at highest risk.

The somatic complaints of children and adolescents with musculoskeletal pain syndromes are typically accompanied by psychological distress, sleep difficulties, and functional impairment across home, school, and peer domains. Psychological distress may include symptoms of anxiety and depression, such as frequent crying spells, fatigue, sleep disturbance, feelings of worthlessness, poor concentration, and frequent worry. Indeed, a substantial number of children with musculoskeletal pain syndromes display the full range of psychological symptoms, warranting an additional diagnosis of a comorbid mood or anxiety disorder (e.g., major depressive episode, generalized anxiety disorder). Sleep disturbance in children with musculoskeletal pain syndromes may include difficulty falling asleep, multiple night awakenings, disrupted sleep–wake cycles with increased daytime sleeping, nonrestorative sleep, and fatigue.

For children and adolescents with musculoskeletal pain syndromes, the constellation of pain, psychological distress, and sleep disturbance often leads to a high degree of functional impairment. Poor school attendance is common, and children may struggle to complete other daily activities relating to self-care and participation in household chores. Decreased physical fitness can also occur, as well as changes in gait and posture, as children avoid contact with or use of the body area affected by pain. Peer relationships may also be disrupted by decreased opportunities for social interaction because of pain. As such, children and adolescents with musculoskeletal pain syndromes often report loneliness and social isolation characterized by few friends and lack of participation in extracurricular activities.

Diagnosis and Differential Diagnosis

The diagnosis of a musculoskeletal pain syndrome is typically one of exclusion when careful, repeated physical examinations and laboratory testing do not reveal an etiology. At initial presentation, children with pain complaints require a thorough clinical history and a complete physical examination to look for an obvious etiology (sprains, strains, or fractures), characteristics of the pain (localized or diffuse), and evidence of systemic involvement. A comprehensive history can be particularly useful in providing clues to the possibility of underlying illness or systemic disease. The presence of current or recent fever can be indicative of an inflammatory or neoplastic process if the pain is also accompanied by worsening symptoms over time or weight loss.

Subsequent, repeated physical examinations of children with musculoskeletal pain complaints may reveal eventual development and manifestations of rheumatic or other diseases. The need for additional testing should be individualized, depending on the specific symptoms and physical findings. Laboratory screening and radiography should be pursued if there is suspicion of certain underlying disease processes. Possible indicators of a serious, vs a benign, cause of musculoskeletal pain include pain present at rest, pain that may be relieved by activity, objective joint swelling on physical examination, stiffness or limited range of motion in joints, bony tenderness, muscle weakness, poor growth and/or weight loss, and constitutional symptoms (e.g., fever, malaise) ( Table 193.1 ). In the case of laboratory screenings, a complete blood count (CBC) and erythrocyte sedimentation rate (ESR) are likely to be abnormal in children whose pain is secondary to a bone or joint infection, SLE, or a malignancy. Bone tumors, fractures, and other focal pathology resulting from infection, malignancy, or trauma can often be identified through imaging studies, including plain radiographs, MRI, and less often technetium-99m bone scans.

The presence of persistent pain, accompanied by psychological distress, sleep disturbance, and/or functional impairment, in the absence of objective laboratory or physical examination abnormalities, suggests the diagnosis of an idiopathic musculoskeletal pain syndrome. All pediatric musculoskeletal pain syndromes share this general constellation of symptoms at presentation. Several more specific pain syndromes routinely seen by pediatric practitioners can be differentiated by anatomic region and associated symptoms. Table 193.2 outlines pediatric musculoskeletal pain syndromes, including growing pains (see Chapter 193.1 ), fibromyalgia ( Chapter 193.3 ), complex regional pain syndrome ( Chapter 193.4 ), localized pain syndromes, low back pain, and chronic sports-related pain syndromes (e.g., Osgood-Schlatter disease).

Treatment

The primary goal of treatment for pediatric musculoskeletal pain syndromes is to improve function rather than relieve pain, and these 2 desirable outcomes may not occur simultaneously. Indeed, it is common for children with musculoskeletal pain syndromes to continue complaining of pain even as they resume normal function (e.g., increased school attendance and participation in extracurricular activities). For all children and adolescents with pediatric musculoskeletal pain syndromes, regular school attendance is crucial, because this is a hallmark of normal functioning in this age-group. The dual nature of treatment, targeting both function and pain, needs to be clearly explained to children and their families to outline better the goals by which treatment success will be measured. Indeed, children and families need to be supported in disengaging from the sole pursuit of pain relief and embracing broader treatment goals of improved functioning.

Recommended treatment modalities typically include physical and/or occupational therapy, pharmacologic interventions, and cognitive-behavioral and/or other psychotherapeutic interventions. The overarching goal of physical therapy is to improve children's physical function and should emphasize participation in aggressive but graduated aerobic exercise. Pharmacologic interventions should be used judiciously. Low-dose tricyclic antidepressants (amitriptyline, 10-50 mg orally 30 min before bedtime) are indicated for treatment of sleep disturbance; selective serotonin reuptake inhibitors (sertraline, 10-20 mg daily) may prove useful in treating symptoms of depression and anxiety if present. Referral for psychological evaluation is warranted if these symptoms do not resolve with initial treatment efforts or if suicidal ideation is present. Cognitive-behavioral therapy (CBT) and/or other psychotherapeutic interventions are typically designed to teach children and adolescents coping skills for controlling the behavioral, cognitive, and physiologic responses to pain. Specific components often include cognitive restructuring, relaxation, distraction, and problem-solving skills; additional targets of therapy include sleep hygiene and activity scheduling, all with the goal of restoring normal sleep patterns and activities of daily living. Parent education and involvement in the psychological intervention is important to ensure maintenance of progress. More intensive family-based approaches are warranted if barriers to treatment success are identified at the family level. These could include parenting strategies or family dynamics that serve to maintain children's pain complaints, such as overly solicitous responses to the child's pain and maladaptive models for pain coping.

Complications and Prognosis

Musculoskeletal pain syndromes can negatively affect the child's development and future role functioning. Worsening pain and the associated symptoms of depression and anxiety can lead to substantial school absences, peer isolation, and developmental delays later in adolescence and early adulthood. Specifically, adolescents with musculoskeletal pain syndromes may fail to achieve the level of autonomy and independence necessary for age-appropriate activities, such as attending college, living away from home, and maintaining a job. Fortunately, not all children and adolescents with musculoskeletal pain syndromes experience this degree of impairment, but many children experience pain that persists for 1 yr or more. Factors that contribute to the persistence of pain are increasingly understood and include female gender, pubertal stage at pain onset, older age of pain onset, increased psychological distress associated with the pain, joint hypermobility, and greater functional impairment. The likelihood of positive health outcomes is increased with multidisciplinary treatment.