Detection of residual consciousness using EEG indicators related to rectal perception: protocol for a diagnostic accuracy study.

Introduction: Accurate diagnosis of disorders of consciousness (DoC), including unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), remains a long-standing and unresolved challenge in clinical practice. Current diagnostic frameworks rely predominantly on behavioral responsiveness, with the Coma Recovery Scale-Revised (CRS-R) serving as the clinical gold standard. However, behavior-based evaluation is intrinsically vulnerable to examiner subjectivity and cognitive-motor dissociation, contributing to misdiagnosis rates of up to 40%. From a theoretical perspective, consciousness comprises both external awareness and self-awareness, yet existing DoC assessments focus almost exclusively on external sensory processing, leaving self-awareness substantially underassessed. This imbalance highlights a critical gap that motivates for complementary assessment approaches targeting underexplored dimensions of consciousness. Methods and analysis: This study protocol aims to develop an EEG-based paradigm and evaluate its feasibility for assessing gut-related interoceptive processing in patients with DoC, using controlled, non-invasive rectal balloon distension. Standardized stimulation procedures, synchronized EEG acquisition, and predefined analytical pipelines will be implemented to characterize the temporal and spatial features interoceptive event-related potentials. Results: Electrophysiological and statistical analyses will be conducted to assess the feasibility, signal characteristics, and response profiles of gut-related interoceptive EEG activity across diagnostic categories. Exploratory analyses will further examine associations between interoceptive EEG markers and clinical behavioral measures. Discussion: By systematically investigating an under assessed dimension of consciousness, this study protocol aims to establish the feasibility and signal-level characteristics of gut-related interoceptive EEG responses in patients with disorders of consciousness. By providing methodological and exploratory evidence at the group level, the findings are intended to inform the design of future hypothesis-driven and validation studies, and to support the longer-term development of complementary assessment approaches that extend beyond behavior-based evaluation, with potential relevance for clinical research and public health-oriented diagnostic strategies. Clinical trial registration: [ClinicalTrials.gov], identifier [NCT07208942].