What is myalgia, specifically in the context of a patient with potential HIV exposure?

What is Myalgia?

Myalgia is muscle pain that can occur throughout the body and represents a common musculoskeletal manifestation in patients with HIV infection, occurring at all stages of disease and potentially as the first manifestation of HIV itself. 1, 2

Definition and Clinical Presentation

Myalgia refers to muscle pain or aching that can affect any muscle group in the body. 3 In the context of HIV infection, myalgia presents as:

• Diffuse muscle pain and tenderness that may be localized or widespread throughout the body 3
• Pain that can occur with or without associated muscle weakness, distinguishing it from frank myopathy 4
• Symptoms that may be accompanied by arthralgia (joint pain), representing the most common forms of musculoskeletal involvement in HIV-infected patients receiving antiretroviral therapy 3, 2

Myalgia in the Context of HIV

Causes of Myalgia in HIV Patients

Myalgia in HIV-infected individuals can arise from multiple etiologies:

• HIV-associated myopathy: Direct muscle involvement from HIV infection itself, which can occur at any stage of disease 1, 4
• Antiretroviral therapy toxicity: Particularly with zidovudine (ZDV) and other nucleoside-analogue reverse-transcriptase inhibitors (NRTIs), causing toxic mitochondrial myopathies 1, 4
• HIV polymyositis: Inflammatory muscle disease with myalgia as a prominent feature 1, 5
• Fibromyalgia syndrome: A chronic pain syndrome characterized by diffuse musculoskeletal pain including myalgia, found in 20% of HIV-infected patients receiving ART 3
• HIV wasting syndrome: Associated with muscle involvement and myalgia 1

Distinguishing Features

Myalgia is more commonly reported in patients receiving zidovudine treatment compared to untreated HIV patients, though both groups can experience muscle pain. 4 Key clinical distinctions include:

• Myalgia without weakness: Elevated serum creatine kinase (CK) may be present (median ~450-485 IU/L), but patients maintain muscle strength 4
• Myalgia with weakness (myopathy): Proximal muscle weakness accompanies the pain, with similar CK elevations 4
• Associated symptoms: When myalgia occurs as part of fibromyalgia syndrome in HIV patients, it significantly impacts functional status, depression, fatigue, sleep quality, and overall quality of life 3

Clinical Significance in HIV Exposure Context

Acute HIV Infection

Myalgia can be an early manifestation of acute HIV infection (acute retroviral syndrome), occurring during the initial weeks after exposure. 1, 2 This presentation warrants:

• Consideration of HIV testing in patients presenting with myalgia and other viral-like symptoms (fever, lymphadenopathy, rash) 2
• Recognition that musculoskeletal symptoms may precede other HIV manifestations 1

Chronic HIV and Treatment Era

In established HIV infection, myalgia prevalence and significance include:

• Common occurrence: Musculoskeletal complications including myalgia are particularly common in advanced stages of HIV infection 2
• Fibromyalgia overlap: 20% of HIV-infected patients on ART meet diagnostic criteria for fibromyalgia, with myalgia as a cardinal feature 3
• Disease duration correlation: Longer HIV disease duration (mean 4.74 years) is associated with higher rates of fibromyalgia-related myalgia 3
• CD4 count relationship: Lower CD4 T-lymphocyte counts correlate with increased prevalence of fibromyalgia and associated myalgia 3

Important Clinical Pitfalls

Do not assume myalgia in HIV patients is solely due to antiretroviral therapy—HIV infection itself commonly causes muscle pain, and withdrawal of medications like zidovudine improves symptoms in only a minority of patients (4 of 15 in one series). 4 Additional considerations:

• Multiple concurrent conditions are possible: A patient may have both HIV-related myopathy and another neuromuscular condition simultaneously 5
• Reactive arthritis consideration: The possibility of HIV infection should be considered in all patients presenting with conditions suggesting reactive arthritis or unexplained musculoskeletal symptoms 2
• Functional impact assessment: When myalgia is present, evaluate for fibromyalgia syndrome, as its detection and treatment can significantly improve depression, fatigue, sleep disorders, and quality of life, potentially increasing ART compliance 3