Diabetic amyotrophy is an incapacitating illness, distinct from other forms of diabetic neuropathy. It is characterized by lower extremity weakness with normal sensation and a predilection for proximal muscles. Presentation is often accompanied by severe pain and weight loss, often improving with glycemic control.
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A 70 year-old female with T2DM presented with severe, sharp, left proximal leg pain; weakness requiring the use of a cane; and 40 lb weight loss over 8 months.
Exam revealed cachexia (weight 46.3 kg, BMI 17.6 kg/m2), normal heart tones, and clear lungs. Neurological exam was normal with the exception of severe muscle atrophy of the left quadriceps, a postural tremor, and decreased muscle strength in the proximal left lower extremity (3/5 left hip, 3/5 left knee, and 5/5 left ankle). Sensation to light touch was normal.
Labs were notable for hypercalcemia (Ca, 12.2 mg/dL), AKI (Cr, 1.23 mg/dL), hypokalemia (K, 2.8 mEq/L), and microcytic anemia (Hb, 10.5 g/dL). Given bone pain, hypercalcemia, renal insufficiency, anemia, and weight loss, diagnosis of multiple myeloma was entertained; however SPEP, UPEP, and serum free light chains were normal, and hypercalcemia was found to be due to primary hyperparathyroidism.
HbA1c was 8.0%. TSH, vitamin B12, folate, CPK, ESR, CRP, and C3/C4 values were normal. A heavy metal panel was normal. Titers for ANA, ANCA, rheumatoid factor, and Lyme disease were negative. CSF showed increased protein (55 mg/dL) and a non-reactive VDRL. CT-chest/abdomen/pelvis revealed no mass. MRI-cervical/thoracic/lumbar spine revealed no mass or disc disease. Radiographs of the femurs revealed mild OA. EMG was consistent with proximal bilateral lumbosacral polyradiculopathy (left > right) without distal peripheral polyneuropathy.
The diagnosis of diabetic amyotrophy was made based on presentation with asymmetric, proximal leg weakness, pain, and weight loss with supportive EMG findings. Other potential causes for myelopathy, namely mass lesion, inflammatory, or neoplastic processes were ruled out. Patient was started on prednisone, pregabalin, metformin, cinacalcet, and discharged. Two months later, pain improved; however, weakness persisted and had become symmetric, with 2/5 muscle strength in both proximal legs.
Conclusion : Diabetic amyotrophy is a rare complication of diabetes. Initially described as occurring asymmetrically, many patients progress to bilateral leg involvement. The natural course is variable, with gradual, but often incomplete improvement in strength and persistent muscle wasting. Improvement is often seen with control of diabetes. After exclusion of alternative causes, EMG helps to confirm the diagnosis.
Matthew Mandell– Internal Medicine Resident Physician, University of Illinois at Chicago/Advocate Christ Medical Center, Chicago, Illinois
Dana Mourad– Medical Student, Chicago Medical School at Rosalind Franklin University of Medicine and Science
Leen Alkhouli– Resident physician, UIC/Advocate Christ Medical Center, Burr Ridge, Illinois
Erin Drever– Clinical Assistant Professor of Medicine and Endocrinology & Metabolism, University of Illinois at Chicago/Advocate Christ Medical Center; Division of Endocrinology and Metabolism, Department of Medicine, University of Illinois at Chicago, Merrionette Park, Illinois
Internal Medicine Resident Physician
University of Illinois at Chicago/Advocate Christ Medical Center
Matthew Mandell is a second-year internal medicine resident at UIC/Advocate Christ Medical Center.
Chicago Medical School at Rosalind Franklin University of Medicine and Science
Dana Mourad is a fourth-year medical student at Chicago Medical School.
UIC/Advocate Christ Medical Center
Burr Ridge, Illinois
Leen Alkhouli, M.D., Internal Medicine resident physician at UIC/Advocate Christ Medical Center
Clinical Assistant Professor of Medicine and Endocrinology & Metabolism
University of Illinois at Chicago/Advocate Christ Medical Center; Division of Endocrinology and Metabolism, Department of Medicine, University of Illinois at Chicago
Merrionette Park, Illinois
Dr. Erin Drever is an Endocrinologist at a large teaching hospital in the Chicago area. She is involved in the UIC-affiliated Advocate Christ Internal Medicine Residency Program with teaching, administrative, and research responsibilities. She is also involved in the UIC Endocrine Fellowship Program with teaching and research responsibilities. Her clinical and research interests include transplant endocrinology, endocrine disorders in pregnancy, and diabetes care delivery models.