Diabetic Myopathy: MRI Patterns and Current Trends

This study retrospectively evaluates diabetic myopathy in a large referral hospital population. It describes the MRI findings and the distribution of muscle involvement, including comparison with clinical parameters. MRI reports of the lower extremities from July 1999 through January 2006 were reviewed and compared with clinical parameters for patients with diabetic myopathy. Clinical parameters (e.g., type of diabetes, hemoglobin A(1C) level, creatine kinase level, and erythrocyte sedimentation rate [ESR]) and the presence of complications, including nephropathy, neuropathy, and retinopathy, were noted. The distribution of muscle involvement and imaging features were reviewed. Over a 79-month period, 21 extremities (11 thighs and 10 calves) of 16 patients were imaged. Fourteen (88%) patients had type 2 diabetes, and two (12%) had type 1 diabetes. Four patients (25%) had disease in more than one location. In the thigh, the anterior compartment was involved in all patients. The posterior compartment was affected in nine (90%) of 10 calves. Muscle infarction and necrosis was seen in eight (38%) extremities. The creatine kinase level, ESR, and hemoglobin A(1C) level were elevated in the majority of cases. Coexisting nephropathy (50%), neuropathy (50%), and retinopathy (38%) were present in these patients. Diabetic myopathy may occur more frequently in patients with type 2 diabetes than previously reported. In this population, T2-weighted and contrast-enhanced images have similar findings, and the increased coexistence of nephropathy makes administration of gadolinium-based contrast agents ill-advised. With a typical clinical presentation and MRI findings, a confident diagnosis can be made, and potentially harmful biopsy is avoided. Diabetic myopathy encompasses a spectrum of diseases, including muscle inflammation, ischemia, hemorrhage, infarction, necrosis, fibrosis, and fatty atrophy. It is usually seen with long-standing, poorly controlled diabetes.