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Toxic myopathies: muscle biopsy features

Rosana Herminia Scola1, Eduardo Rafael Pereira, Paulo José Lorenzoni

  • 1Neuromuscular/Neurology Division, Internal Medicine Department, Hospital de Clínicas, Universidade Federal do Paraná, Rua General Carneiro 181, 80060-900 Curitiba, PR, Brazil.

Arquivos De Neuro-Psiquiatria
|April 11, 2007
PubMed

Insights

Toxic myopathy, often caused by drugs like corticosteroids, affects young adults. Muscle biopsies frequently show type 2 fiber atrophy, even with normal enzyme levels, highlighting the need for careful diagnosis.

Area of Science:

  • Neurology
  • Toxicology
  • Pathology

Background:

  • Acquired myopathies are frequently caused by drugs and toxic substances.
  • Toxic myopathies represent a significant group of muscle disorders with diverse etiologies.

Purpose of the Study:

  • To describe the clinical features, etiology, and diagnostic findings in a series of patients with toxic myopathy.
  • To analyze the role of specific substances, laboratory tests, and muscle biopsy in diagnosing toxic myopathy.

Main Methods:

  • Retrospective case series of 32 patients diagnosed with toxic myopathy.
  • Review of clinical data, serum creatine kinase levels, needle electromyography, and muscle biopsy findings.

Main Results:

  • Corticosteroids were the most common causative agent (56.2%).
  • Normal serum creatine kinase levels were observed in 65.4% of patients.
  • Type 2 fiber atrophy was the most frequent histological finding on muscle biopsy (59.3%).

Conclusions:

  • Toxic myopathy, particularly in young adults, is often induced by common medications.
  • Diagnosis requires a comprehensive approach, including detailed history, electromyography, and muscle biopsy, as serum enzyme levels can be misleading.

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