62 (18%) patients reported some recollection of the time of clinical death (table 1).

Several theories have been proposed to explain NDE. We did not show that psychological, neurophysiological, or physiological factors caused these experiences after cardiac arrest. Sabom22 mentions a young American woman who had complications during brain surgery for a cerebral aneurysm. The EEG of her cortex and brainstem had become totally flat. After the operation, which was eventually successful, this patient proved to have had a very deep NDE, including an out-of-body experience, with subsequently verified observations during the period of the flat EEG.

With lack of evidence for any other theories for NDE, the thus far assumed, but never proven, concept that consciousness and memories are localised in the brain should be discussed. How could a clear consciousness outside one's body be experienced at the moment that the brain no longer functions during a period of clinical death with flat EEG?22 Also, in cardiac arrest the EEG usually becomes flat in most cases within about 10 s from onset of syncope.29,30 Furthermore, blind people have described veridical perception during out-of-body experiences at the time of this experience.31 NDE pushes at the limits of medical ideas about the range of human consciousness and the mind-brain relation.

Research should be concentrated on the effort to explain scientifically the occurrence and content of NDE. Research should be focused on certain specific elements of NDE, such as out-of-body experiences and other verifiable aspects. Finally, the theory and background of transcendence should be included as a part of an explanatory framework for these experiences.