CLINICAL

• Most common cause of weakness and disability with AIDS is muscle atrophy and wasting from nutritional deficiency and repeated infections. Non-HIV related muscle diseases are likely most common muscle disorders seen in people with HIV and on ART. Frailty is accentuated in aging in PLWH and includes a phenotype of decreasing strength.
• 3 most common HIV-related primary muscle disorders in HIV are HIV myopathy, idiopathic polymyositis and myopathy due to toxicity from NRTIs (related to agents now mostly replaced by safer agents). Less common primary muscle disorders include lymphoma, inclusion body myositis, and infections such as toxoplasmosis. Inflammatory autoimmune myopathies, metabolic, and genetic are also reported among PLWH.
• Myalgias, muscle tenderness and weakness of the proximal muscles are common features of all primary muscle disorders in HIV. Inclusion body myositis spreads to include distal muscles as well.
• Differentiating among the many etiologies of primary muscle disorders is difficult. Empiric treatment and retrograde Dx is common.
• Infectious causes of myopathy must be ruled out before empiric immunosuppression. These include pyomyositis by Staph. aureus (90% of cases) and Toxoplasma. Pyomyositis usually presents with localized tenderness and swelling more than weakness; toxoplasmosis presents insidiously with diffuse muscle wasting and weakness similar to non-infectious etiologies.
• Secondary causes of muscle weakness and tenderness include rhabdomyolysis (may be ART-related due to ritonavir or cobicistat cyp3A4 inhibition; rhabdomyolysis has also been attributed directly to some agents), involvement in non-Hodgkin’s lymphoma, cocaine abuse, trauma and seizures. These can present in all stages of HIV infection.