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What is statin myopathy?
Statin associated myalgias and cramps occur in up to 20% of statin users and are dependent on dose and associated medications.
Rhabdomyolysis occurs at a rate of 0.44 per 10,000 patient-years.
Usually the statin myopathy is self-limited and, after discontinuation of the statin, will resolve in a few weeks to months.
However, in a minority of patients, statins stimulate a necrotizing autoimmune myopathy that progresses even after the statin is discontinued.
These patients present with proximal muscle weakness, markedly elevated CK levels, an irritable myopathy on EMG, and muscle edema.
Muscle biopsy shows a necrotizing myopathy with minimal inflammation.
Most of these patients have developed anti-HMG-CoA reductase antibodies and often require aggressive immunosuppressive therapy.
Sources
- Askanas V, Engel WK: Inclusion body myositis: Muscle fiber molecular pathology and possible pathogenic significance of its similarity to Alzheimer’s and Parkinson’s disease brains. Acta Neuropathol 116:583-595, 2008.
- Karpati G, O’Ferrall EK: Sporadic inclusion body myositis: pathogenic considerations. Ann Neurol 65:7-11, 2009.
- Oh TH, Brumfield KA, Hoskin TL et al.: Dysphagia in inflammatory myopathy: clinical characteristics, treatment strategies, and outcome in 62 patients. Mayo Clinic Proc 82:441-447, 2007.
