Background: Toxic myopathies are a frequent cause of acquired myopathy in adults. The type of drugs or toxins involved varies greatly according to the epidemiologic context in which they are evaluated. An etiological, clinical and histological review of the toxic myopathies diagnosed in a group of study of muscular diseases in a third level hospital was carried out.
Methods: An eight year retrospective study of clinical and histological review of patients in whom muscle biopsy was performed to diagnose toxic myopathies in the Hospital Clinic i Provincial of Barcelona was performed.
Results: The most frequent causes of toxic myopathy with clinical relevance were those due to the consumption of zidovudin, ethanol, prednisone, heroin, and neuroleptic, hypolipemiant and diuretic drugs, with other causes being less frequent. In 52% of the cases an elevation of muscle enzymes (creatinkinase) was observed. In 51% it was attributed to the administration of a drug at therapeutic doses, in 34% to voluntary intoxication (attempt at autolysis or drug dependence) and in 15% the cases were accidental. The histologic study of the muscle biopsy was normal in 10% of the cases and changes indicative of a determined etiology were observed in 65% and were non-specific in the remaining 25%. More than a half of the patients were asymptomatic at 3 months of initiation of the symptoms.
Conclusions: Toxic myopathies often follow a paucisymptomatic form. Most have a non-specific histologic substrate and improve upon suppression of the producing cause. The performance of muscle biopsy gives positive or negative clinically useful information in 60% of the cases, by discarding other possible causes of myopathy.