Exp Neurobiol.  2013 Sep;22(3):232-234. 10.5607/en.2013.22.3.232.

A Case of Thyrotoxic Myopathy with Extreme Type 2 Fiber Predominance

• Kim TJ
• Lee HS
• Shin JY
• Kim DG
• Kim SM
• Sung JJ
• Lee KW

• KMID: 2165486
• DOI: http://doi.org/10.5607/en.2013.22.3.232

Abstract

In hyperthyroidism, many patients had neuromuscular symptoms and clinical weakness correlated with free thyroxine (T4) concentrations. The common clinical symptoms of chronic thyrotoxic myopathy were characterized by progressive weakness in proximal muscles and atrophy. A 55-year old woman was visited our hospital with two years of progressive weakness of both legs. Physical examination showed diffuse enlargement of the thyroid gland, muscle atrophy and tachycardia. Motor examination showed proximal weakness in both legs. Serum creatine phosphokinase was normal and electromyography showed a myopathic pattern. Serum thyroxine (T4) was greatly increased and serum thyroid stimulating hormone was very low. Muscle biopsy showed mild atrophic change and type 2 fiber predominance. The patient's symptoms were improved during treatment with methimazole. Herein we report a case of thyrotoxic myopathy with extreme type 2 fiber predominance histologically.

Keyword

thyrotoxic myopathy; hyperthyroidism; type 2 fiber

MeSH Terms

Atrophy
Biopsy
Creatine Kinase
Electromyography
Female
Humans
Hyperthyroidism
Leg
Methimazole
Muscles
Muscular Atrophy
Muscular Diseases
Physical Examination
Tachycardia
Thyroid Gland
Thyrotropin
Thyroxine
Creatine Kinase
Methimazole
Thyrotropin
Thyroxine