Persisting weakness after withdrawal of a statin.

An 81-year-old woman treated with simvastatin for several years followed by atorvastatin for about 1 year presented with fatigue, weakness and unsteady gait. The finding of elevated creatine kinase (CK) and symmetric muscle weakness around shoulders and hips led to suspicion of a toxic statin-associated myopathy. Atorvastatin was withdrawn, but her weakness persisted. Owing to persisting weakness, an autoimmune myopathy (myositis) was suspected, but initially disregarded since a muscle biopsy showed necrotic muscle fibres without inflammatory cell infiltrates and myositis-specific autoantibodies were absent. After 18 months with slowly progressive weakness and increasing CK values, awareness of new knowledge about autoimmunity as a cause of necrotic myopathy, led to a successful treatment trial with intravenous immunoglobulines, followed by steroids and metothrexate. Antibodies to the target enzyme of statins (HMGCR (3-hydroksy-3-methylglutaryl-coenzyme A reductase)) were detected in her serum, and she was diagnosed with autoimmune necrotic myositis probably triggered by atorvastatin.