EEG correlates of confusional state after traumatic brain injury

Post-traumatic amnesia (PTA), recently conceptualized as part of the broader syndrome known as post-traumatic confusional state (PTCS), marks a critical phase of recovery following moderate-to-severe traumatic brain injury (TBI). Indeed, this state is characterized not only by anterograde memory impairment but also by disorientation, agitation, and attention deficits. Given the phenotypic overlap between PTA/PTCS and delirium--both marked by fluctuating cognitive and attentional disturbances--EEG represents a promising tool for elucidating shared pathophysiological mechanisms. While delirium is typically associated with diffuse EEG slowing and the presence of slow-wave activity (SWA), thought to reflect underlying global cortical disruption, it remains unclear whether PTCS exhibits similar EEG underpinnings. In this prospective longitudinal study, we assessed dynamic EEG correlates of PTCS using the Grand Total EEG (GTE) score. We enrolled 42 consecutive TBI patients, classifying them at baseline into PTA/PTCS or emerged from PTA/PTCS, based on validated clinical assessments. Patients with PTA/PTCS exhibited significantly higher baseline GTE scores compared to TBI controls, reflecting severe EEG abnormalities characterized by diffuse slowing and disrupted rhythmic activity. Longitudinal follow-up revealed significant EEG improvements paralleling clinical recovery, confirming EEGs sensitivity to dynamic clinical changes. Furthermore, the severity of EEG abnormalities significantly correlated with the duration of PTA/PTCS, underscoring EEGs potential as an objective biomarker for monitoring recovery trajectories. Notably, these findings were independent of pharmacological confounders, as medication regimens were not significantly different across groups and timepoints. Our results support a reconceptualization of PTA/PTCS as a functional encephalopathy, analogous to delirium, with EEG slowing reflecting widespread yet reversible cortical dysfunction. By capturing these transient yet clinically critical changes, clinical EEG-- quantified via GTE scores--offers a novel tool for diagnosing PTA/PTCS, stratifying its severity, and objectively monitoring its evolution in acute and subacute rehabilitation settings.