Fig. 4

Auditory evoked potentials interpretation and prognostic value in comatose and DoC patients after CA. Pre-requisite for ERP interpretation: presence of BAEP, MLAEP and N100 (primary auditory cortices responses). Use of neuromuscular blockage agents is recommended if artefacts limit the recording. Part A Shows brainstem auditory evoked potentials (BAEP) (auditory nerves and brainstem integration of the auditory stimuli). Part B Shows middle latency auditory evoked potential (MLAEP). Part C Shows late auditory ERPs with Mismatch Negativity (MMN), P300 and “local–global” effect. MMN is elicited by an auditory passive “oddball” paradigm (series of standard frequent tones and deviant infrequent tones). MMN is obtained by subtracting the ERP of the deviant and standard tones. P300 is elicited by the same “oddball” paradigm with intermix of scarce subject’s own-name stimuli. «Local–global» effect (figure adapted from Bekinschtein et al. PNAS, 2009 [140]) is recorded during an active counting task (tones with local and global deviations), patients having to count these “global deviations” which elicit a spatially cerebral distributed response called the “global effect”