Analysis of behavioral and EEG correlatives of attention in the dynamics of recovery of consciousness following severe brain injury

Abstract

Objective : to determine the behavioral manifestations and electroencephalographic correlates of modality-nonspecific attention using a clinical model of severe brain injury (SBI). Patients and methods. 35 patients with SBI in the dynamics of post-coma recovery of mental activity (a study group) and 23 healthy subjects (a control group) were examined. The behavioral manifestations of NSA from coma to clear consciousness were analyzed in the patients. Changes in the pattern of EEG and in the indices of its coherence in the presence and activation of different forms of attention (an orienting response to the sound and eye opening; involuntary and voluntary visual forms), by applying specially developed computerized techniques, were investigated. The features of associated with attention changes in interhemispheric EEG coherence (IHC) with the data of 3T diffusion tensor tractography of the corpus callosum (CC) were compared. Results. Attention disorders were shown to be essential and an «axial disorder» in patients with SBI. There were statistically confirmed qualitative and quantitative differences attention-associated changes in the EEG pattern and IHC in reversible and chronic unconsciousness. The important favorable prognostic sign proved to be reactive changes in interhemispheric EEG relations, including frontal ones characterized by the absence of clear external manifestations of consciousness in the very earliest stages. There was a significant correlation between the preservation of CC tracts (primarily, the rostrum, anterior portion, and splenium) and attention-related reactivity of IHC, which reflects the specific, though nonrigid, structural determinacy of the latter.