Which sequence best describes the cascade leading to CIM?

• A. Predisposing factors → Steroid toxicity → Priming factor → Proteolysis → CIM
• B. Steroid toxicity → Predisposing factors → Proteolysis → CIM
• C. Proteolysis → CIM → Predisposing factors → Steroid toxicity
• D. Predisposing factors combined with Steroid Toxicity and Priming factor lead to Proteolysis and CIM

Answer: (D)

CIM results from a multifactorial cascade where baseline patient factors combine with pharmacologic and priming stimuli to turn on muscle proteolysis. Predisposing factors set the stage, steroid toxicity adds a harmful metabolic insult, and a priming factor further sensitizes the muscle to breakdown. When these elements come together, the proteolytic pathways in skeletal muscle are upregulated, leading to rapid protein degradation and the development of critical illness myopathy. That’s why the sequence that describes predispositions plus steroid toxicity and an additional priming factor combining to drive proteolysis—and then CIM—best fits the pathway. The other options place factors in an incorrect order or imply proteolysis and CIM occur independently or before the triggering factors, which doesn’t align with how the cascade actually progresses.