Neurophysiological assessment for evaluating residual cognition in vegetative and minimally conscious state patients: a pilot study

The aim of this study was to assess residual cognitive function and perform outcome evaluation in vegetative state (VS) and minimally conscious state (MCS) patients, using Neurowave, a system able to monitor event-related potentials (ERPs) induced by neurosensory stimulation. Eleven VS and five MCS patients underwent neurological examination and clinical evaluation performed using validated clinical and behavioral scales; they also underwent neurosensory stimulation, which consisted of administration of target images (rare stimuli), relevant to the patient's personal history and having emotional significance, alternated with nontarget images ("standard" stimuli), which had no emotional significance. All simultaneous ERP responses at baseline (T0) and at three months from T0 (T1) were recorded. At T0 we found significant differences between the VS and MCS patients for the N200 (p=0.02) and P300 (p=0.04) waves. The neurophysiological analysis at T1 showed a significant difference only for P300 (p=0.02), probably due to the improvements observed in the VS subjects for the N100 (p=0.009) and N200 (p=0.02) sensory components. Neurophysiological assessment for evaluating residual cognition in vegetative and minimally conscious state patients: a pilot study Our findings seem to show the value of ERP monitoring in VS and MCS patients as a means of investigating residual cognitive function. This approach could guide early therapeutic and rehabilitation interventions, and contribute to identifying better diagnostic and prognostic markers for use in unresponsive or low-responsive patients.