Malignant hyperthermia susceptibility revealed by myalgia and rhabdomyolysis during fluoroquinolone treatment

Fluoroquinolones cause myalgia, but this complication is not clearly docume nted. We describe a patient who developed myalgia and rhabdomyolysis during fluoroquinolone treatment. The patient was a 33-year-old man treated with norfloxacin for common cystitis. He complained of general muscular fatigue, tendon disorders, and articular pain during treatment. When the antimicrob ial agent was stopped, symptoms decreased, with persistence of slight myalg ia for 10 days, Rhabdomyolysis was detected. Six months later, investigatio n by P-31 magnetic resonance spectroscopy revealed an oxidative disorder an d an abnormal abundance of phosphomonoesters. In vitro contracture tests le d to a diagnosis of malignant hyperthermia susceptibility. Our case shows t hat for any subject presenting myalgia with rhabdomyolysis triggered by flu oroquinolone treatment, the presence of a latent myopathy should be investi gated.