Diagnosing Diffuse Aches and Pains
Diffuse aches and pains, with features suggesting an origin in muscles, bones or joints, are symptoms that commonly bring patients to the family medicine practitioner. The practitioner has the responsibility to differentially diagnose from among the numerous diverse disorders that include such complaints, as well as identify those patients who have particularly serious underlying conditions and, therefore, will need referral for specialist investigations.
While it is clearly inappropriate to subject all such patients to elaborate, sometimes invasive, investigation, it is necessary to initiate a process of screening for likely conditions, using the history, physical examination, and simpler laboratory investigations. Once a diagnosis is suspected, the subsequent confirmatory investigations generally follow a standard pattern. The prize of early diagnosis depends more on the initial screening than the subsequent investigation, and is thus mainly in the hands of the general family medicine practitioner.
For those cases that seem to defy definitive diagnoses, the responsibilities of the physician are: first, to decide which cases warrant further investigation for serious underlying conditions; and, second, how to handle those in which there is no clear evidence of significant underlying disease. This article is concerned primarily with the first aspect. A conceptual approach that includes simple clinical and laboratory screening tests — and relies on a simplified flow chart to lead to the appropriate diagnostic considerations — is described in the following sections along with useful diagnostic pointers.
Early Pointers to a Likely Diagnosis
Figure 1 provides a listing of some of the more important conditions that can cause diffuse aches and pains, and is formatted as a simplified flow chart showing the early pointers to a likely diagnosis. An initial consideration involves the erythrocyte sedimentation rate (ESR), which is important in separating the inflammatory from the non - inflammatory disorders. It is a nonspecific test, but its familiarity and simplicity make it an invaluable screening test. A markedly elevated ESR may be the first pointer to a number of conditions, such as certain arthritic disorders, polymyalgia rheumatica, multiple myelomatosis, systemic lupus erythematosus, or secondary carcinomatosis. On the other hand, in the presence of a normal ESR, the serum alkaline phosphatase (SAP) level may yield important information. For example, the SAP level may be increased in both liver and metabolic bone diseases. Hence, the value of the SAP level as a screening test in the context of diffuse aches and pains with an elevated level pointing to the need to exclude conditions such as liver disease and osteomalacia, while normal SAP and normal ESR levels may point to other conditions to specifically consider in the differential diagnosis. After taking the history and examining the patient, the appropriate laboratory tests to request can then be considered. The conditions specified in Figure 1 will be considered briefly in turn, emphasizing the features that provide the most useful diagnostic pointers.
This includes rheumatoid arthritis as well as conditions such as ankylosing spondylitis and psoriatic arthritis. The most important clue in the history is the complaint of distressing early morning stiffness, lasting half an hour or sometimes much longer. Patients with ankylosing spondylitis are predominantly men in the third or fourth decade,1 may describe episodes of iritis or of painful heels (“plantar fasciitis” or Achilles tendonitis), or give a positive family history. Rheumatoid factor is tested negative.
In the case of ankylosing spondylitis, morning stiffness is an equally important early symptom, but the local signs of arthritis are too easily overlooked. Any reduction in spinal movements is significant, but the most useful tests are lumbar spinal flexion and lateral bending range of motion. Tenderness of the sacroiliac joints and reduced chest expansion (1
Physical examination in the early rheumatoid patient (most typically middle aged women) will show signs in peripheral joints involvement (especially in the hands and feet). These joints are tender on compression, swollen, painful on full movement with limited range of motion. A “polymyalgic” presentation of rheumatoid arthritis is rare, and the diagnosis is unlikely in the absence of local evidence of joint inflammation.3,4
Psoriatic arthritis appears in 5% of patients with psoriasis. Skin lesions are clear and there are characteristic X-ray findings. “Pencil-in-cup” deformity2 and sacroiliac joint involvement are common occurrences on X-ray.
“Secondary carcinomatosis can present with aches and pains as a result of skeletal deposits and can be much more difficult to diagnose at presentation.”
Screening Tests For Inflammatory Polyarthritis
If the history and/or signs raise a suspicion of inflammatory polyarthritis, then the routine laboratory screening tests are the ESR and the autoantibody tests for rheumatoid factors (latex test) and antinuclear antibodies (ANA). The latex test may be positive early in rheumatoid arthritis (approximately 80% of cases), while the ANA test is a test for systemic lupus erythematosus. A medication-induced lupus reaction should always be considered. X-rays of the pelvis and lumbar spine may be useful if ankylosing spondylitis is suspected, by revealing sacroiliitis and bamboo spine sign, but radiology is unlikely to be helpful in early rheumatoid arthritis. Similarly, tissue typing for human leukocyte antigen (HLA-B27) is not very useful as a screening test for ankylosing spondylitis.
This is defined by the taxonomy of the International Association for the Study of Pain (IASP) as diffuse, aching pain, stiffness in the neck, shoulder or hip girdle, with a raised ESR, sometimes associated with giant cell vasculitis which is predominantly steroid responsive.6 This common and important condition must be excluded in all older patients complaining of diffuse aches and pains. Its importance lies in its frequent association with giant cell arteritis, which may lead to irreversible blindness. This can be prevented by appropriate corticosteroid treatment, but prevention requires diagnosis, which is easily overlooked, particularly in the very elderly. In a typical case, the patient will complain of distressing ‘muscular’ aches, particularly in a proximal (girdle) distribution, with severe, prolonged and incapacitating early morning stiffness.
The key screening test is the ESR, which will almost invariably be markedly elevated, sometimes over 100 mm/h (an unexpectedly normal result should be repeated). Some of these patients also have signs and symptoms of giant cell arteritis (such as an inflamed segment of a temporal artery and tenderness over the temporal artery), and most of them will require specialist investigation to exclude conditions that may mimic polymyalgia rheumatica (such as multiple myelomatosis). However, it is critical to recognize polymyalgia rheumatica as a possible diagnosis, and the important clues are girdle muscle pains, early morning stiffness, and an elevated ESR.