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[Toxic myopathies: clinical, etiologic, and histologic study of 74 cases]
J Fernández-Solá1, E Pedrol, F Masanés
1Servicio de Medicina Interna. Hospital Clinic i Provincial, Barcelona.
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.
Insights
Toxic myopathies, often caused by common medications like zidovudine and prednisone, frequently present with mild symptoms and improve after drug withdrawal. Muscle biopsies are diagnostically useful in many cases.
Area of Science:
- Neurology
- Toxicology
- Pathology
Context:
- Toxic myopathies are a significant cause of acquired muscle disease in adults.
- Etiology varies based on geographic and epidemiological factors.
- This study reviewed toxic myopathies diagnosed at a tertiary care hospital.
Purpose:
- To conduct an etiological, clinical, and histological review of toxic myopathies.
- To identify common causative agents and clinical presentations.
- To evaluate the diagnostic utility of muscle biopsy in toxic myopathy.
Summary:
- Retrospective analysis of 8 years of muscle biopsies for toxic myopathy diagnosis.
- Identified zidovudine, ethanol, prednisone, heroin, and other drug classes as frequent causes.
- Muscle enzyme elevation (creatine kinase) occurred in 52%; biopsy was non-specific in 25% and normal in 10%.
Impact:
- Toxic myopathies often present with subtle symptoms and non-specific histological findings.
- Muscle biopsy provides clinically relevant information in 60% of cases, aiding differential diagnosis.
- Most patients improve after cessation of the causative agent, highlighting the importance of identifying the toxin.