[Mitochondrial abnormalities and ocular myopathies with downward-spreading evolution. Apropos of 2 new cases]

Area of Science:

• Neurology
• Mitochondrial Diseases
• Muscle Biology

Context:

• Ocular myopathies are a group of neuromuscular disorders affecting eye muscles.
• Familial occurrence suggests a genetic component in some cases.
• Long-term progression highlights the chronic nature of the disease.

Purpose:

• To report two unique cases of descending ocular myopathy with unusual systemic manifestations.
• To investigate the underlying cellular pathology using electron microscopy and histochemistry.
• To contribute to the understanding of mitochondrial myopathies.

Summary:

• Two patients, aged 32 and 49, presented with childhood-onset ptosis and progressive involvement of ocular, facial, pharyngeal, neck, and limb muscles over 20 years.
• Both experienced significant unexplained weight loss and had thyroid nodules without overt thyroid dysfunction.
• Muscle biopsies revealed mitochondrial aggregates with diverse changes, predominantly in type 1 muscle fibers in one case.

Impact:

• These findings expand the clinical spectrum of ocular myopathies.
• The study underscores the importance of investigating mitochondrial abnormalities in unexplained muscle weakness and systemic symptoms.
• Provides insights into the heterogeneity of mitochondrial myopathies and their potential systemic effects.