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Mitochondrial myopathy is a group of multi-system diseases in which mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) defects lead to structural and functional dysfunction of mitochondria. The clinical manifestations of mitochondrial myopathy are complex and varied, and the testing for mtDNA and nDNA is not widely available, so misdiagnosis or missed diagnosis is common. Chronic progressive external ophthalmoplegia (CPEO) is a common type of mitochondrial myopathy, which is characterized by blepharoptosis. Here we report a 38-year-old female with mitochondrial myopathy presented with chronic numbness and weakness of the limbs, accompanied by blepharoptosis that was recently noticed. Laboratory and head magnetic resonance imaging (MRI) examinations showed no obvious abnormalities. Muscle and nerve biopsies showed characteristic ragged red fibers (RRFs) and large aggregates of denatured mitochondria. Testing for mtDNA and nDNA showed a known mutation c.2857C>T (p.R953C) and a novel variant c.2391G>C (p.M797I) in the polymerase gamma ( POLG )gene, so the patient was diagnosed as mitochondrial myopathy. Clinicians should pay more attention to long-term unexplained skeletal muscle diseases with recent onset blepharoptosis. Histopathologic examination and genetic testing are of great value in the early diagnosis and therapeutic intervention.

Objective To evaluate the current treatments and possible adverse reactions of metabolic myopathy, and to develop the best solution for evidence - based treatment. Methods Taking metabolic myopathy, mitochondrial myopathy, lipid storage myopathy, glycogen storage diseases, endocrine myopathy, drug toxicity myopathy and treatment as search terms, retrieve in databases such as PubMed, Cochrane Library, ClinicalKey database, National Science and Technology Library (NSTL), in order to collect the relevant literature database including clinical guidelines, systematic reviews (SR), randomized controlled trials (RCT), controlled clinical trials, retrospective case analysis and case study. Jadad Scale was used to evaluate the quality of literature. Results Twenty - eight related articles were selected, including 6 clinical guidelines, 5 systematic reviews, 10 randomized controlled trials and 7 clinical controlled trials. According to Jadad Scale, 23 articles were evaluated as high-quality literature (≥S 4), and the remaining 5 were evaluated as low-quality literature (< 4). Treatment principles of these clinical trials, efficacy of different therapies and drug safety evaluation suggest that: 1) Acid a-glycosidase (GAA) enzyme replacement therapy (ERT) is the main treatment for glycogen storage diseases, with taking a high-protein diet, exercising before taking a small amount of fructose orally and reducing the patient's physical activity gradually. 2) Carnitine supplementation is used in the treatment of lipid storage myopathy, with carbohydrate and low fat diet provided before exercise or sports. 3) Patients with mitochondrial myopathy can take coenzyme Q10, vitamin B, vitamin K, vitamin C, etc. Proper aerobic exercise combined with strength training is safe, and it can also enhance the exercise tolerance of patients effectively. 4) The first choice to treat the endocrine myopathy is treating primary affection. 5) Myopathies due to drugs and toxins should remove pathogenic drugs and toxins. Conclusions Most of metabolic myopathies are genetic diseases, and they cannot achieve a radical cure at present. Gene therapy is the fundamental way. Endocrine myopathy and drug toxicity myopathy need to remove the primary affection or pathogenic drugs. Evidence-based medicine can provide the best clinical evidence assessment method for metabolic myopathy. [ABSTRACT FROM AUTHOR]