Respiratory Chain Complex-I Defect Mimicking Myasthenia |
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Authors: | Finsterer J Oberman I Reitner A |
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Institution: | (1) Ludwig Boltzmann Institute for Research in Epilepsy and Neuromuscular Disorders, Vienna, Austria;(2) Ophthalmologic Department, Vienna University School of Medicine, Vienna, Austria;(3) Postfach 348, 1180 Wien, Austria |
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Abstract: | In a 67-year-old woman with ptosis, double vision, dysphagia, ambiguous Tensilon tests, normal acetylcholine-receptor antibodies, normal thymus, and repeatedly abnormal responses to low-frequency repetitive stimulation, ocular myasthenia was suspected. Pyridostigmin was ineffective, but corticosteroids improved the abnormalities. Despite this therapy, lower-limb weakness developed. Reevaluation disclosed abnormal increase of serum lactate during slight exercise, myogenic electromyography, ragged-red fibers, reduced oxidative enzyme staining and abnormally shaped and structured mitochondria on muscle biopsy, and a respiratory chain complex-I defect on biochemical investigation of the muscle homogenate. Respiratory chain disorder due to complex-I defect with abnormal decremental response to low-frequency repetitive stimulation was diagnosed. It is concluded that respiratory chain disorders due to a complex-I defect may mimic ocular myasthenia clinically, electrophysiologically, and even therapeutically. |
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Keywords: | Ophthalmoplegia corticosteroids immunosuppressants repetitive stimulation electrophysiology double trouble myopathy mitochondriopathy |
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