Correlation of MRI with Muscle Biopsy Findings in Critical Illness Myopathy

Objective: To clarify the relationship between imaging and histopathologic abnormalities in critical illness myopathy (CIM). Background: CIM is a common condition in patients with prolonged intensive care unit stay. Pathological findings are heterogeneous, ranging from acute necrotizing myopathy, to diffuse atrophy, to the most common pattern of selective thick filament (myosin) loss. Previous reports highlighted the muscle MRI abnormalities in this condition, but did not include detailed description of the pathology associated with them. Design/Methods: We describe the clinical, electrophysiologic, imaging and pathology findings in a patient ultimately diagnosed with myosin loss myopathy. Results: A 38-year-old woman with history of juvenile arthritis, was treated with high dose corticosteroids for one month due to acute respiratory distress syndrome, and developed progressive bilateral leg pain associated with proximal muscle weakness. Examination showed cushingoid facial appearance and proximal symmetric muscle weakness (4/5). Muscle MRI revealed hyperintense T2/STIR signal symmetrically throughout the lower extremity musculature, and diffuse gadolinium enhancement on T1. CK was low, and EMG showed myopathy without abnormal spontaneous activity. Muscle biopsy confirmed widespread myosin loss, without any necrosis or inflammation. Conclusions: Muscle MRI findings of edema (increased T2/STIR signal) and gadolinium enhancement can be caused by non-inflammatory disorders, including loss of thick filaments, as seen in critical illness myopathy. Prospective analysis of more cases would be useful. Disclosure: Dr. Labin has nothing to disclose. Dr. Manousakis has nothing to disclose.