EEG oscillatory changes following rehabilitative tactile and thermal stimulation in disorders of consciousness: a longitudinal and pilot study

Recent advances in the understanding of sensory processing in disorders of consciousness (DoC) have highlighted the potential of exteroceptive stimuli, particularly tactile stimulation. Unlike auditory or visual inputs, tactile stimuli engage primary somatosensory pathways that may be preserved even in severely brain injured patients. The aim of our study is to identify cortical neurophysiological markers for diagnosis, prognosis, and structured rehabilitative planning.

Seven patients were included. EEG was recorded at baseline (T0) and after 1 month of repeated tactile and thermal stimulation administered in a randomized manner to both hands (T1). Spectral power changes were computed by contrasting stimulation-related activity with resting state and analyzed across frequency bands and cortical regions.

At T0, sensory stimulation elicited weak and spatially limited EEG modulation, predominantly involving slow-frequency activity, consistent with reduced cortical responsiveness. Following the stimulation period (T1), EEG responses showed increased amplitude and spatial extent, characterized by a relative suppression of slow oscillations and enhanced modulation of higher-frequency activity over fronto-central and parietal regions.

Repeated tactile and thermal stimulation were associated with longitudinal changes in EEG oscillatory patterns, reflecting possible modulation of cortical responsiveness associated with sensory stimulation. The assessment of stimulation-induced EEG oscillatory changes may represent exploratory neurophysiological indicators of residual cortical responsiveness that could support future studies on sensory processing in DoC patients.