Dynamic HRV Assessment Based on Gamma Auditory Stimulation

While the Coma Recovery Scale-Revised (CRS-R) remains the gold standard for assessing prolonged disorders of consciousness (pDoC), its reliance on overt motor responsiveness and the necessity for repeated assessments to ensure accuracy have driven the clinical search for efficient, motor-independent complementary methods. To address this need, this study investigated the classification value of autonomic responses elicited by standardized Gamma auditory stimulation. In a cohort of 55 pDoC patients (32 UWS/VS and 23 MCS/EMCS), we implemented a concise 10-minute protocol comparing heart rate variability (HRV) between resting state and stimulation-induced conditions. Results demonstrated that while resting-state measurements lacked discriminative capacity, autonomic reactivity triggered by stimulation revealed significant differences. Specifically, MCS/EMCS patients exhibited a distinct pattern of vagal activation (evidenced by decreased heart rate and increased pNN); conversely, UWS/VS patients displayed trends consistent with autonomic rigidity or sympathetic dominance. Classifiers based on these response features (particularly ∆NN50 and ∆pNN) achieved a cross-validated AUROC of 0.71, with the optimal model configuration reaching 0.81. Requiring only standard headphones and a Holter monitor, this method offers rapid, non-invasive, and motor-independent advantages, serving as an effective supplement to the CRS-R.