Changes in Trapezius Muscle Structure in Fibromyalgia and Chronic Trapezius Myalgia

Objectives: To reveal possible changes in muscle structure related to chronic myalgia. Methods: Muscle biopsies from tender areas of the trapezius muscle, and from corresponding areas of healthy subjects were studied by electron microscopy. Results: Fibres with an aberrant myofibrillar structure and an altered distribution and structure of the mitochondria and capillaries with altered endothelial structure were observed. Conclusions: The aberrant myofibrillar structure might correspond to the moth-eaten and the ragged-red fibres seen in light microscopy. The capillary changes could be related to disturbances in muscle microcirculation.