Case Presentation: A 51-year-old African-American female was admitted to the hospital with 3 days of bilateral calf pain, described as a severe cramping pain that started in the left medial calf. The patient first noticed the pain after walking two blocks. The pain did not subside with rest. The next day, the patient noticed similar pain in the right medial calf. The bilateral calf pain progressively worsened to the point that she was having difficulty ambulating. Both exertion and direct pressure worsened the pain. Ibuprofen provided no relief. She denied recent travel, surgery, trauma, over-exertion, or heat exposure. Her past medical history was pertinent for a deep venous thrombosis of the left peroneal vein one year ago that was treated with 4 months of rivaroxaban. Two months ago, she was diagnosed with diabetes mellitus type II (hemoglobin A1c 10.2%). She was started on glargine 10 units daily. Examination of the lower extremities revealed only exquisite tenderness to palpation of the upper medial head of the gastrocnemius bilaterally.
Laboratory workup showed an elevated blood glucose of 277 mg/dL and high creatine kinase (CK) of 1235 units/L, ultimately peaking at 2414 units/L. Aldolase was also elevated at 11.4 units/L. CBC, BMP, liver function tests, ANA, ENA, ANCA, ESR, CRP, and TSH were all normal. Venous duplex ultrasonography of the lower extremities showed no deep venous thromboses. An MRI with contrast was remarkable for bilateral multifocal medial gastrocnemius muscle abnormalities in a pattern characteristic of diabetic myonecrosis (Image 1).
Discussion: Diabetic myonecrosis is a rare complication of longstanding diabetes. It is thought to be a microvascular complication and occurs in patients with other diabetic complications such as diabetic nephropathy, retinopathy, and neuropathy. The pathophysiology is not well understood, but there is no macrovascular occlusion or stenosis. It most often occurs in the thigh, and can sometimes be bilateral, but is rarely symmetric. Clinical hallmarks are pain with exertion and palpation, with slowly progressive onset. Depending on extent of muscle infarction, weakness may also be present. Diagnosis is usually suspected in a diabetic patient who presents with unexplained muscle pain and an elevated CK. MRI with contrast is diagnostic in the correct clinical setting. While strong evidence is lacking, non-steroidals or aspirin are usually recommended for treatment, though most cases resolve spontaneously.
Conclusions: Our case of diabetic myonecrosis is unusual given the symmetric distribution to the medial head of the gastrocnemius bilaterally; it is also notable because the patient did not have longstanding diabetes or other diabetic complications. Diabetic myonecrosis is a rare disease, but probably more common than is presently diagnosed, thus it is essential to maintain a high index of suspicion in a hospitalized diabetic patient with unexplained muscle pain.