Orbicularis oculi: morphological changes mimicking mitochondrial cytopathy in a series of control normal muscles.

摘要

Introduction:? Orbicularis oculi (OO) muscle has recently proposed as a suitable muscle for biopsy to diagnose mitochondrial cyopathy: Methods:? Enzyme histochemical and immunohistochemical studies were performed on OO muscle obtained from 18 patients aged 37-87?years (median 64?years), 6 males, 12 females, who were undergoing routine upper blepharoplasty surgery. Results:? We confirmed the marked type II fibre (fast myosin heavy chain) predominance (89%) but also noted a different proportion and distribution of mitochondria in these fibres with occasional pseudo-'ragged-red' fibres with prominent subsarcolemmal and cytoplasmic aggregation of mitochondria. Cytochrome oxidase-negative fibres and true 'ragged-red' fibres were found at all ages over 40?years at levels that approach those used for diagnosis of mitochondrial cytopathy in peripheral or limb skeletal muscles. Conclusion:? We would therefore urge caution in the use of OO as muscle biopsy for diagnosis of mitochondrial cytopathy and advise concomitant biopsy of limb skeletal muscle and/or supplementary genetic studies.