Musculoskeletal Symptom Complexes

History

Because the differential diagnosis of musculoskeletal pain is extensive, a comprehensive history must be obtained. Important information includes the acuity of onset of illness and presence or absence of fever. Symptoms that are acute, persistent, and accompanied by fever are more likely to be caused by infection. Chronic or subacute symptoms often are the result of noninfectious illnesses.

Important information obtained in the history of the present illness includes the onset and location, description of the progression and severity of the musculoskeletal pain, and whether pain medication has been used and has been helpful. History is elicited of change in gait, ability to bear weight or move the affected area, joint or soft tissue swelling, and presence of induration, erythema, and warmth. A history of trauma, strenuous physical activity, previous or recent illnesses, growth and development, travel, animal or insect exposures, sick contacts, and medication use is important. A review of systems, including history of fever, weight loss, skin or mucous membrane lesions, pharyngitis, eye inflammation, lymphadenopathy, respiratory or cardiac symptoms, abdominal pain, vomiting or diarrhea, recent sexually transmitted diseases, or neurologic symptoms, is crucial in determining whether the musculoskeletal abnormalities are associated with systemic disease. Family history, including history of autoimmune or inflammatory diseases, can be helpful.

Physical Examination

The primary focus of the physical examination is on pinpointing the location of symptoms to generate an accurate differential diagnosis and facilitate diagnostic testing. Examination of infants or young children is difficult because they are unable to verbalize the exact location of discomfort. Because musculoskeletal pain can be due to disease affecting a variety of structures, including joints, bones, soft tissues, muscles, nerves, or blood vessels, careful examination of each of these systems is necessary.

Vital signs document the presence or absence of fever, hypothermia, or cardiovascular instability. Height, weight, head circumference, and general appearance of the child should be noted. Poor growth or weight loss could be consistent with inflammatory bowel disease (IBD) or other chronic inflammatory processes, malignancy, or chronic infections such as tuberculosis. Examination of the eyes may reveal conjunctival hyperemia consistent with Kawasaki disease. Mucous membranes are examined for the presence of ulcers (IBD, Behçet disease, systemic lupus erythematosus [SLE]), an enanthem (group A streptococcal infection, enterovirus infection), or hyperemia (Kawasaki disease). Lymphadenopathy can be seen in juvenile idiopathic arthritis (JIA), malignancy, and Kawasaki disease. The chest is palpated for bone tenderness (malignancy, multifocal osteomyelitis, pleurodynia) and for decreased (pleural effusion) and increased (consolidated lung) tactile fremitus during vocalization; the chest is also percussed for dullness (pleural effusion or consolidation). Auscultation can reveal rales, rhonchi, or wheezing (pneumonia associated with hematogenous dissemination of infection to bones, joints, or muscles) or decreased breath sounds such as in pleural effusion (occasionally seen with JIA and SLE). Cardiac examination may reveal a new murmur (endocarditis or acute rheumatic fever [ARF]) or muffled heart sounds (pericarditis). The abdomen should be assessed for tenderness, masses (psoas abscess, tumor), hepatomegaly, or splenomegaly (JIA, malignancy, endocarditis). The skin is evaluated carefully for rash (viral infections, associated bacterial infections or intoxications, Kawasaki disease and other vasculitides).

Careful examination of bones, joints, muscles, and nervous system is particularly important. The examiner should note how the patient holds the affected limb and whether areas of skin or soft tissue appear swollen or red. Gait and stance are observed. The bones and muscles in the affected limb should be palpated, and passive and active range of motion of joints should be evaluated. Pain in the lower extremities can be referred from the back, pelvis, abdomen, or hip. A careful examination of the back and pelvis is necessary to rule out diskitis, vertebral osteomyelitis, pelvic osteomyelitis, or abscess. Bones of the spine and pelvis are palpated, and the spine is assessed for abnormalities in flexion or extension. Skin overlying the vertebral bodies should be examined for the presence of a hemangioma, hair, pit, or mass associated with spinal dysraphism. Infection or structural abnormalities of the hip can cause pain referred to the knee. Examination of the hip joint should be performed in all children with a symptom or sign referable to the lower extremity. Neurologic examination includes evaluation for presence and symmetry of deep tendon reflexes, evaluation for clonus, and sensory examination and estimation of muscle strength. Foot deformities may suggest underlying neurologic conditions.

Laboratory Evaluation and Imaging

The laboratory and radiologic evaluation of patients with musculoskeletal pain is guided by findings on history and physical examination. If infection is suspected, attempts should be made to obtain blood cultures and joint, bone, or tissue culture (depending on location of disease) before initiation of antibiotic therapy. Synovial fluid cell count and cultures are recommended, particularly for patients with monoarticular arthritis, fever, and no other sites or signs of systemic disease. A complete blood count (CBC) can be helpful to evaluate for neutrophilia suggestive of infection and inflammatory syndromes, anemia of chronic or systemic disease, thrombocytosis as part of the acute phase response of many inflammatory and infectious syndromes, or thrombocytopenia due to bone marrow suppression of post-viral or oncologic disease. Inflammatory markers (erythrocyte sedimentation rate [ESR] and C-reactive protein [CRP]) can be abnormal with infection, inflammatory disease, and hematologic malignancy. Use of other diagnostic tests depends on the differential diagnosis generated on the basis of the history and physical examination.

If a bone or joint disease is suspected, a plain radiograph of the affected area generally is indicated. Both anteroposterior and lateral views should be obtained because abnormalities sometimes can be missed with a single view. Depending on suspected site of the problem, specialized views sometimes are required ( Fig. 24.1 ). Plain radiographs can identify fracture, chronic bone infection, joint effusion, soft tissue swelling, tumor, and structural abnormalities of bone. Ultrasound is useful in identifying joint effusions, particularly in the hip, although a normal ultrasound does not exclude infectious or inflammatory changes in the joint. MRI may be necessary to diagnose bone infections, particularly in the acute phase and muscle (i.e., myositis) or soft tissue infections. MRI also can be useful to establish the diagnosis and extent of bone involvement of malignancies. Radionuclide bone scan can be useful when multifocal disease is suspected, such as in chronic nonbacterial osteomyelitis (CNO), formerly chronic recurrent multifocal osteomyelitis (CRMO).

Limb Pain

The causes of limb pain in children are extensive and include the broad categories of infection, inflammatory disease, malignancy, trauma, and orthopedic problems ( Box 24.1 ). These conditions may involve the joints, bones, muscles, or soft tissue of the affected limb.