Abstract
Intensive care unit (ICU) acquired sarcopenia and myosteatosis are increasingly recognized complications of critical illness, characterized by a rapid loss of skeletal muscle mass, quality, and function. These conditions result from a complex interplay of systemic inflammation, immobilization, catabolic stress, mitochondrial dysfunction, and immune dysregulation, often culminating in impaired recovery, prolonged hospitalization, and increased long-term mortality. First identified in survivors of sepsis and prolonged mechanical ventilation, these muscle abnormalities were initially described using computed tomography-based assessments of muscle area and density. Subsequent advances in imaging, biomarker discovery, and functional testing have enabled earlier detection and risk stratification across diverse ICU populations. While nutritional optimization and early mobilization form the cornerstone of current prevention and treatment strategies, the emergence of novel approaches, including automated artificial intelligence-based screening, neuromuscular electrical stimulation, and targeted pharmacologic therapies, has broadened the clinical scope of interventions. Despite their significant prognostic implications, ICU-acquired sarcopenia and myosteatosis remain under-recognized in routine critical care practice. This mini-review aims to synthesize current knowledge regarding their pathophysiology, available diagnostic modalities, prognostic relevance, and the evolving landscape of therapeutic strategies for long-term functional recovery in critically ill patients.