Event-related brain potential modulation in patients with severe brain damage

Abstract

Objective: The limited evidence and inconsistency of purposeful behaviors in patients in a minimally conscious state (MCS) asks for objective electrophysiological marker of the level of consciousness. Here, a comparison between event-related potentials (ERPs) was investigated using different level of stimulus complexity.

Methods: The patients in vegetative state were 11 and the MCS patients were 6 [corrected]. Three oddball paradigms with different level of complexity were applied: sine tones, the subject's own name versus sine tones and other first names. Latencies and amplitudes of N1 and P3 waves were compared.

Results: Cortical responses were found in all MCS patients, and in 6 of 11 patients in VS. Healthy controls and MCS patients showed a progressive increase of P3 latency in relation to the level of stimulus complexity. No modulation of P3 latency was observed in the vegetative patients.

Conclusions: These results suggest that the modulation of P3 latency related to stimulus complexity may represent an objective index of higher-order processing integration that predicts the recovery of consciousness from VS to MCS when clinical manifestations are inconsistent.

Significance: Modulation of P3 latency related to stimulus complexity could provide valuable information about the cognitive capabilities of unresponsive patients.