Myalgia

Overview

Myalgia, often known as muscle pain, is a frequent symptom among individuals seeking medical attention. Almost everyone will suffer muscular discomfort at some time in their lives. Among the most prevalent reasons include very high levels of effort, trauma, and viral infections. While many causes are harmless and self-limiting, myalgia may be a precursor to illnesses with severe morbidity.

A detailed physical examination and a careful assessment of the patient's history may generally restrict the number of probable causes of myalgia to a manageable handful. Selective testing may be required to detect or eliminate certain illnesses and to focus treatment in cases with persistent or severe myalgia with no known etiology.

It is important to differentiate myalgia from myopathy (muscle disease) and myositis (muscle inflammation). Although myopathy and myositis may cause myalgia, most individuals with myalgia have neither. It is also useful to separate diffuse from localized symptoms. 

Causes of Myalgia

The etiologies of myalgias can be divided based upon diffuse versus focal symptoms.

Diffuse myalgias:

The most common causes of diffuse myalgia are:

• Systemic infection: including viral, bacterial, and spirochetal diseases. As a prominent example, dengue fever is sometimes called "break bone fever" due to the severe muscle and joint pain associated with this virus.
• Rheumatic disease: especially polymyalgia rheumatica (PMR), inflammatory myopathy, or autoinflammatory disease. 
• Non-inflammatory conditions: such as fibromyalgia and chronic fatigue syndrome (CFS), also known as systemic exertion intolerance disease (SEID). 
• Medications: particularly the use of statins (with or without creatine kinase elevation), ciprofloxacin, bisphosphonates, aromatase inhibitors, or withdrawal from antidepressant therapy. 
• Metabolic disorders: such as mitochondrial myopathy, vitamin D deficiency, and scurvy, can lead to myalgias, although these are much rarer causes. 
• Liver disease: such as chronic infection and autoimmune disease.
• Endocrine disorders: such as thyroid disease and adrenal insufficiency can lead to myopathic pain. Of note, glucocorticoid-induced myopathy often leads to muscle weakness and wasting without pain. 
• Psychiatric: as with somatic manifestations of depression.

Localized myalgias:

The most common causes of localized myalgia are:

• Unusually strenuous exercise or overuse.
• Soft tissue disease (such as bursitis, trauma, or infection).
• Pyomyositis.
• Myofascial pain syndrome.
• Muscle infarction or compartment syndrome.

Myalgia may be multifactorial in addition to these causes. For example, a patient may have rheumatoid arthritis, fibromyalgia, and pes anserinus pain syndrome all at the same time.

Symptoms and signs of Myalgia

Myalgia's main symptoms is muscle pain. The discomfort feels like a pulled muscle and can be worse by both rest and activity. Muscles might be tender and swollen as well.

Additional symptoms of myalgia may include:

• Deep muscle pain in the local area or widespread pain.
• Dull or sharp aching pain.
• Mild or severe pain that may last minutes or be constant.
• Fever and chills if there is an infection.
• Joint pain associated with muscle pain.
• Fatigue that interferes with your normal activity.
• Feeling depressed if the pain is constant.

How is Myalgia's cause can be diagnosed?

When patients appear with myalgia, it is typical for the diagnosis to be unable to be confirmed during the initial visit. This might be related to the requirement to monitor symptoms over time and seek laboratory or other diagnostic testing. In fact, tracking the progression of symptoms and signs over time can be quite beneficial.

Myalgia is related with a wide range of medical disorders. In individuals who have a consistent pattern of symptoms, the diagnosis can be made quickly. However, significant ambiguity is usual following the initial review. Selective testing and close monitoring may be required for several months to limit the number of possible explanations.

The doctor should seek to identify patients with a significant or life-threatening condition early in the examination of patients with myalgia. Myalgia-causing conditions can produce substantial pain, however serious medical crises with myalgia are uncommon. Bacterial infections, particularly endocarditis and approaching sepsis, require prompt diagnosis and treatment since they can cause generalized myalgia, fever, chills, arthralgia, lethargy, and back pain. In extreme situations, rhabdomyolysis can cause generalized myalgias, renal failure, and/or compartment syndrome.

Medical history: 

The patient's history provides a useful starting point in narrowing down the long list of potential causes for myalgia. Particular attention should be given to mode of onset, location of pain, and associated symptoms.

The first step in sorting out the cause of myalgia is to understand the specific nature of the patient's muscle pain:

1. Did the muscle pain begin suddenly or gradually? If sudden in onset, did it follow trauma or an unusually strenuous activity? Is the muscle pain worse in the morning?

• Acute onset with prominent constitutional symptoms, for example, suggests infection (such as bacterial sepsis, pyomyositis, influenza or acute hepatitis B). Polymyalgia rheumatica (PMR) is characterized by acute onset of myalgia in the neck, shoulders, upper arms, buttocks, and thighs in an older adult, especially if accompanied by morning stiffness.
• Subacute myalgia is common in medication-induced causes (such as statin-induced myalgia) and can appear weeks to months after starting treatment.
• The insidious onset and persistent symptoms of chronic hepatitis C infection, hypothyroidism, hypercalcemia, and vitamin D insufficiency are prevalent. This is also a common trend in people suffering from fibromyalgia, chronic fatigue syndrome (CFS), also known as systemic exertion intolerance disease (SEID), myofascial pain syndrome, and a somatization condition. Furthermore, morning muscular pain and stiffness are strongly predictive of PMR or other inflammatory arthritis.

2. Is the muscle pain associated with pain elsewhere? Is it near joints? If so, are they axial joints, such as the shoulder and hips?

• Shoulder and hip pathology, in particular, tend to cause referred pain to proximal muscles. Referred pain accounts for the prominent myalgia described by patients with PMR and rheumatoid arthritis involving the shoulders.

3. Is there a particular distribution of muscle pain? 

• Statin-induced myalgia typically presents as proximal, symmetric muscle weakness and soreness. In contrast, diffuse myalgia, fever, headache, malaise, and a nonproductive cough are typical of a viral infection, such as influenza. 

4. Is there redness, swelling or warmth in the area of the muscle pain? Is the muscle painful to touch? 

• Pyomyositis, abscess, muscle infarction, or compartment syndrome may cause focal muscle tenderness. Pyomyositis and abscess may cause localized inflammatory findings as well.

5. Is the myalgia associated with muscle weakness? Is it difficult to arise from a chair or reach above the head? 

• Objective muscle weakness is not expected with fibromyalgia, myofascial pain syndrome, or PMR; these common causes of muscle pain can be placed lower on the list of possibilities in the face of demonstrable muscle weakness. 

6. Have there been muscle cramps? 

The etiology of muscle cramps is often not found, but can be caused by several conditions:

• Structural disorders such as flat feet.
• Unusual positioning during work or sleep.
• Neurologic disorders such as Parkinson disease.
• Muscle injury such as trauma or fall.
• Dehydration.
• Exercise-associated muscle cramping.
• Electrolyte abnormalities.
• Medications such as diuretics, statins, and beta agonists.
• Leg cramps occurring at night are discussed separately. 

Other history — The cause of myalgia may not be apparent until additional details of the patient's medical history are revealed. These include:

1. Asking about associated symptoms: the presence or absence of associated symptoms can be quite helpful in pointing toward or against a particular cause. The clinician should undertake a detailed review of systems with particular attention paid to:

• Constipation.
• Depression.
• Fatigue.
• Fever.
• Joint pain or swelling.
• Paresthesias.
• Rash or hyperpigmentation.
• Weight change.
• Nausea, vomiting or diarrhea.

Constipation, lethargy, and weight gain are frequent hypothyroidism symptoms, but rash or hyperpigmentation indicate infection or adrenal insufficiency, respectively. Fever indicates infection or systemic rheumatic disease (such as systemic lupus erythematosus) or autoinflammatory disease (such as familial Mediterranean fever), whereas joint swelling indicates inflammatory arthritis. Paresthesias may indicate a neuropathic disease that causes myalgia due to referred pain or the presence of a vasculitic process.

2. Patient demographics: such as age and gender. For example, newly diagnosed systemic lupus erythematosus and rheumatoid arthritis are most common among young adult women, while PMR is seen exclusively among adults over the age of 55.

3. Past medical history: such as a prior diagnosis of thyroid disease, hepatitis C, diabetes, or hyperparathyroidism.

4. Trauma: a change in activity or function, recent injury, or unusually strenuous exercise may trigger muscle pain, which is typically localized.

5. Psychologic assessment: it may aid in the diagnosis of depression or a somatization disorder as a cause of myalgia.

Physical examination:

While the history might give vital clues to the cause of myalgia, the physical examination can provide strong, objective evidence for myopathy (muscle disease) or another explanation for the symptoms.

Although a patient with myalgia may find it difficult to participate fully with a muscle test, the discovery of weakness can be very useful in limiting the list of probable causes of symptoms by dismissing many. For example, if a patient with myalgia develops proximal muscular weakness in all four extremities, the focus of diagnostic investigations should shift to inflammatory myopathy (such as polymyositis), hypothyroidism, drug-induced myopathy, or hypercalcemia. It is critical to recognize objective weakness since weakness (with or without myalgia) is a common complaint even in the absence of apparent loss of motor function.

Even patients in severe pain may generally exert full effort for a limited period of time to provide the examiner with a feeling of whether muscular strength is normal. Aside from assessing muscle strength in the usual proximal and distal muscle groups (such as the deltoids, wrist extensors, grip, thigh flexors, and ankle flexors and extensors), assessing neck flexor strength may be beneficial because these muscles are a powerful and often overlooked proximal muscle group.

Myalgia can have its sources outside of the muscles. Because of this, as well as the fact that disorders causing myalgia may impact other organ systems, a full physical examination should be performed, with special attention paid to the existence of the following physical findings:

• Fever (which may suggest viral infection, pyomyositis, endocarditis, or impending sepsis).
• Hypotension (as may be found in patients with sepsis).
• Hyperpigmentation and postural hypotension (as may be present in adrenal insufficiency).
• Cutaneous lesions (such as those found in systemic lupus erythematosus, vasculitis, Lyme disease, psoriasis, or endocarditis).
• Ecchymoses (suggestive of recent trauma).
• Limited shoulder and hip range of motion (consistent with PMR) or spinal disease (as may be noted in patients with spondyloarthropathy).
• Joint inflammation (swelling, heat, warmth, and/or limited motion) in the peripheral joints (as is typical of rheumatoid arthritis, psoriatic arthritis, or systemic lupus erythematosus).
• Bursal or tendon tenderness with more limitation of active motion than passive motion (compatible with bursitis or tendonitis).
• Tender points (as with fibromyalgia) or trigger points (suggestive of myofascial pain syndrome), although the ability to distinguish tender and trigger points is controversial. While the presence of multiple tender points in characteristic locations is highly suggestive of fibromyalgia, their absence does not exclude the diagnosis.
• Severe, focal muscle pain should suggest the possibility of muscle infarction, compartment syndrome, or pyomyositis.
• Delayed relaxation of reflexes, slowed speech, dry skin, hoarse voice or other signs of hypothyroidism.
• Depressed or flattened affect (as an indication of depression or as associated with a somatization disorder).

Laboratory studies:

Watchful waiting without laboratory investigation may be suitable for minor symptoms, since symptoms typically improve on their own with time. However, for more serious symptoms (e.g., acute pain or muscular weakness), some laboratory tests can be very useful in ruling in or ruling out illnesses that remain in the differential diagnosis after a thorough history and physical examination.

For most patients with substantial myalgia, a complete blood count, urinalysis, and tests of renal and liver function are recommended as an initial examination. Serum calcium, albumin, phosphate, TSH, CK, and 25-hydroxyvitamin D levels may be relevant to examine depending on the specific symptoms, risk factors, and physical findings.

The following tests may also prove helpful in certain clinical situations:

• Blood cultures and serologic testing for infectious agents (such as parvovirus and viral hepatitis)
• ESR, CRP: These may be helpful to identify the presence of systemic inflammation, as with infection and systemic rheumatic disease (especially PMR and inflammatory myopathy). On the other hand, a normal ESR is the expected finding in patients with fibromyalgia. However, caution must be taken in interpreting these test results as elevations in the ESR and CRP are not specific. In addition, normal or unimpressive results rarely rule out a particular cause of myalgia.
• Autoantibodies: Autoantibodies, such as antinuclear antibodies (ANA) for suspected systemic lupus erythematosus, anti-neutrophilic cytoplasmic antibodies (ANCA) for suspected ANCA-associated vasculitis, and rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies for suspected rheumatoid arthritis, should be limited to patients with a moderate Widespread use of these autoantibody tests for all myalgia patients is likely to result in an unacceptably high incidence of false-positive results.
• Testing of cortisol production, such as morning serum cortisol or adrenocorticotropic hormone (ACTH) stimulation test, are helpful to diagnose or rule out adrenal insufficiency.

Imaging studies:

Radiographs, MRIs, and other imaging tests are not frequently used to diagnose myalgia. Assessment of erosive arthritis (rheumatoid arthritis and others), fracture, inflammatory muscle illness, or localized muscle disease is restricted (pyomyositis, muscle infarction).

Neurophysiology studies:

An electromyogram (EMG) combined with nerve conduction studies (NCS) may be useful in confirming the diagnosis of inflammatory or metabolic myopathy as well as a neuropathic process.

Tissue sampling (eg, aspiration or biopsy):

Most patients with myalgia will not require tissue sampling. However, it may be diagnostic for patients with suspected abscess, inflammatory myopathy, vasculitis, or systemic lupus erythematosus.

Management of myalgia

There are no defined treatment guidelines or professional consensus on how to treat myalgia. The history, physical examination, and selected tests may be very helpful in determining the etiology that will guide management.

If medication-induced myalgia is suspected, a drug-free trial is recommended, but only after weighing the therapeutic benefit of such a trial against the dangers of discontinuing the medicine. However, it may take weeks or even months to determine whether myalgia was caused by a medicine. A prominent exception is polymyalgia rheumatica, a disorder that often improves rapidly and dramatically after a few days of low-dose corticosteroid therapy. In fact, this prompt response to therapy might aid in the confirmation of the diagnosis.

When the underlying reason cannot be determined, patients should be continuously monitored and treated symptomatically. Heat, rest, acetaminophen, nonsteroidal anti-inflammatory medications, and/or muscle relaxants may be used as empiric therapy in the absence of particular contraindications.

Suspicion of a specific ailment for which specialized treatment is indicated (for example, referral to a rheumatologist for suspected PMR) or severe, functionally-limiting symptoms, particularly if they are worsening or chronic, are indications for referral.

Conclusion

Myalgia is the medical term for muscular pain. Muscle pain is a sign of a variety of diseases and disorders. Myalgia can be acute (short-term) or persistent (long-term). Muscle discomfort is the most common symptom of myalgia. The discomfort is similar to a pulled muscle, and it can be worse by both rest and activity. Muscles might also feel painful and swollen. Myalgia may also cause deep muscular pain in the local location or widespread pain. A dull or severe throbbing pain, Mild to severe pain that may last minutes or be persistent If you have a fever and chills, you probably have an infection. Joint discomfort that is accompanied by muscular ache, Fatigue that interferes with your daily activities, feeling despondent if the pain is continuous.

Overuse, injury, or strain are the most prevalent causes of myalgia. Myalgia, on the other hand, might be caused by infections, drugs, or as a reaction to a vaccine. Dehydration can cause muscular pain, especially in persons who engage in strenuous physical activity such as working out. It is also an indication of acute rejection following heart transplant surgery. Myalgia should be treated symptomatically if the etiology is unknown. Heat, rest, paracetamol, NSAIDs, and muscle relaxants are common treatments.