Myotonic Potentials in the Myopathy Induced by HMG-CoA Reductase Inhibitor

HMG-CoA reductase inhibitor is widely used for the treatment of dyslipidemia, and for the prevention of stroke and cardiovascular disease. However, it is necessary to consider the adverse effects associated with this drug. Myopathy is a well-known side effect of statin therapy, but myotonic potentials in cases with statin myopathy have thus far been reported only rarely. We report four cases of myopathy with myotonic potentials on electromyography after multidrug administration. All of the patients recovered shortly after statin withdrawal.