During comatose states occurring after hypoxic-ischemic brain injuries or general anesthesia, the patients lose their awareness and become unresponsive to external stimuli. Nevertheless, their brain EEG reactivity to various somatosensory stimuli is preserved to various degrees. Evoked potential measurements, while very useful in assessing primarily the integrity of the sub-cortical pathway, offer limited information about the cortical function itself. The discontinuous “burst-suppression” (BS) EEG activity that appears during deep comatose states (Synek’s grade 4-5) is a cortical phenomenon under the influence of subcortical activity. The current dogma is that when the bursting occurrence can be altered by external stimuli, then this may be an indication of a better prognostic. Nevertheless, even when some stimuli can appear to evoke bursts (i.e clapping), at stimulus repetition, other seem to fail. This makes the investigation of BS reactivity appear an unreliable prognostic marker. As there are no standardized protocols for assessment of BS reactivity, its clinical value remains poorly understood. This presentation reviews our current work at the ComaEEG.RO on standardizing measures of BS reactivity, using patient investigations and experimental studies in rodents. Monitoring the “suppressed” brain integrity may become increasingly important with increasing use of therapeutic general anesthesia and hypothermia during the coming years.