This prospective observational study aims to evaluate sarcopenia in intensive care patients with intracranial pathologies using ultrasound and to compare the predictive performance of different artificial intelligence models. Rectus femoris muscle thickness will be measured by ultrasound on ICU admission (Day 0) and Day 7. Prealbumin levels will be assessed on Days 0, 3, and 7, and the modified Nutrition Risk in Critically Ill (mNUTRIC) score will be calculated on the first day of ICU admission. Clinical, laboratory, and ultrasonographic data will be integrated into different artificial intelligence models to predict sarcopenia status on Day 7. The study aims to determine the effectiveness of artificial intelligence in the early identification of sarcopenia and to support future clinical decision-making in intensive care practice.

This study is designed as a prospective observational study. Patients admitted to the Level III Intensive Care Units of Trabzon University Faculty of Medicine, Kanuni Training and Research Hospital, Kaşüstü Campus, due to intracranial pathologies between January 1, 2026, and June 30, 2026, will be included. Approximately 100-150 patients are planned to be evaluated.

Demographic data of the enrolled patients will be recorded, and the modified Nutrition Risk in Critically Ill (mNUTRIC) score will be calculated on the first day of intensive care unit admission. Rectus femoris muscle thickness will be evaluated by ultrasonography on Day 0 and Day 7 of ICU admission. All ultrasonographic measurements will be performed using the same ultrasound device and by the same investigator according to a standardized protocol. During the measurements, the patient will be positioned supine, the knee will be kept in extension, and the muscle will be evaluated in a relaxed position. Three repeated measurements will be obtained at each assessment, and the mean value will be recorded.

As part of the laboratory assessment, prealbumin levels will be measured on Days 0, 3, and 7. Biochemical parameters evaluated during routine clinical follow-up will be recorded from the hospital information system.

No intervention, additional procedure, or treatment modification will be performed as part of this study. All data will consist of observational data obtained during routine clinical follow-up. Data collection will be conducted by a resident physician from the Department of Anesthesiology and Reanimation with experience in intensive care.

The collected clinical, laboratory, and ultrasonographic data will be provided to different artificial intelligence models, and their accuracy and performance in predicting sarcopenia development on Day 7 will be evaluated. The primary objective of the study is to assess the predictive performance of artificial intelligence models, including ChatGPT, Gemini, and Claude, for Day 7 sarcopenia development in intensive care patients with intracranial pathologies. Secondary objectives include comparing artificial intelligence predictions with clinical assessments, comparing predictive performance among different artificial intelligence models, and evaluating the potential usability of artificial intelligence models as clinical decision-support tools in intensive care practice.

All data will be de-identified before analysis, and patient confidentiality will be maintained. Study data will be stored in a secure digital environment accessible only to the research team.

Inclusion Criteria:

• Age between 18 and 65 years
• Admission to the intensive care unit due to intracranial pathology (intracerebral hemorrhage, epidural hemorrhage, subdural hemorrhage, subarachnoid hemorrhage, intracranial tumors, or ischemic stroke)
• Informed consent obtained from the patient or legally authorized representative

Exclusion Criteria:

• Age <18 years or >65 years
• Failure to achieve nutritional targets according to ESPEN guidelines
• Palliative care or home care patients
• Morbid obesity (BMI ≥40 kg/m²)
• History of neuromuscular disease
• Lower extremity amputation
• History of trauma affecting the thigh region
• Pregnancy

Adult intensive care unit patients aged 18-65 years admitted with intracranial pathologies, including intracerebral hemorrhage, epidural hemorrhage, subdural hemorrhage, subarachnoid hemorrhage, intracranial tumors, and ischemic stroke.

Individual participant data will not be shared. The collected data will be used only for the purposes of this study and will remain confidential in accordance with institutional and ethical regulations.