Evaluating Brain Activity in Patients With Chronic Disorders of Consciousness After Traumatic Brain Injury Using EEG Microstate Analysis During Hyperbaric Oxygen Therapy

Background: Hyperbaric oxygen (HBO) therapy is an efficacious intervention for patients with prolonged disorders of consciousness (pDOC). Electroencephalographic (EEG) microstate analysis can provide an assessment of the global state of the brain. Currently, the misdiagnosis rate of consciousness-level assessments in patients with pDOC is high. Therefore, we aimed to assess the consciousness levels and outcomes of patients by analyzing changes in EEG signals during HBO therapy.

Methods: EEG data were collected from 32 patients with traumatic brain injury before and after 20 min of HBO therapy. EEG data were obtained during HBO therapy sessions. Modified k-means clustering was used to segment EEG signals into microstates. A paired sample t test was used to compare the microstate characteristics before and during HBO therapy.

Results: The duration, occurrence, and coverage of microstate D significantly increased in the minimally conscious state (MCS) group after therapy. Significant increases in the same parameters were observed in microstate A among patients in the unresponsive wakefulness state group. Furthermore, patients with greater improvements in Coma Recovery Scale-Revised scores (i.e., improvements of more than three points) showed significant increases in the duration, occurrence, and coverage of microstate D. Both the MCS group and the improvement group presented significant increases in the duration, occurrence, and coverage of microstate D during therapy.

Conclusions: Microstate D may be associated with the recovery of consciousness levels in patients. This study verified the safety and feasibility of real-time EEG during HBO therapy for patients with pDOC. The changes in EEG microstate characteristics during HBO therapy can serve as a significant complement to electroencephalographic assessment indices for patients with pDOC and may be useful for predicting the recovery of consciousness levels.