Högskolan i Skövde

Near-death experiences are a difficult area to study. By gathering studies documenting EEG recordings during cardiac arrest, this review aims to identify any possible patterns in the dying process and potentially give a point of comparison for NDE-like studies. A total of 16 articles fitting the criteria were found and evidence of two patterns of death were identified. Of a total 165 patients, ~80% died in an orderly fashion with mostly low frequencies (delta/theta) present, the EEG amplitude declining alongside heart function and blood pressure, falling under 2uV into electrocerebral silence before or within five minutes after cardiac arrest. The other 20% began similarly but had a sudden surge of high EEG-frequencies close to time of death, with activity more resembling higher levels of wakefulness than unconsciousness. These end-of-life electrical surges (ELES) are seemingly triggered by a drop in oxygen and are mostly seen before cardiac arrest. Several articles propose a connection between these surges and spreading depolarizations, a phenomenon caused by neuronal injury with a wide variety of effects. Based on the unusually high activity and the potential effects of depolarizations, the authors present the ELES-window as a key part of NDEs.