External ophthalmoplegia associated with Hashimoto's thyroiditis and recovered on corticosteroid treatment.

Five-year follow-up of a young male patient is presented. Total external ophthalmoplegia developed 1 week after an upper respiratory tract infection. After 3 years of the course, hyperthyreosis and clinical signs of thyroid-associated ophthalmopathy occurred. Hashimoto's thyroiditis and ultrastructural signs of mitochondrial damage of striated muscle were found by histological investigations. The paresis of the external ocular muscles recovered after long-term corticosteroid treatment. On the basis of clinical symptoms and histological results, the authors supposed that an immunological reaction had caused mitochondrial damage in the striated muscles, which also resulted in thyroiditis. This case history points that autoimmune mechanism more frequently might participate in the pathogenesis of chronic external ophthalmoplegia, and the symptoms might precede organ-specific or perhaps systemic autoimmune disorders.