[Changes of pupil size in brain death patients].

The representative criteria of brain death in Japan is Takeuchi Criteria (Koseisho Criteria), which is the definition of irreversible loss of brain function (functional brain death). The 3rd item of that criteria is "fixed pupil" and pupil size more than 4 mm. The 4th item is loss of the brain nerve reflexes including the light reflex. Three cases of brain death by whole brain destruction (organic brain death) who showed slow changes of pupil size were reported. Except fixed pupil, one case fulfilled Takeuchi Criteria. Other two cases fulfilled all items of Takeuchi Criteria, showing the same pupil size accidentally at the first and the second judgements. But, they changed their pupil size slowly and continuously after the examinations, showing tendencies toward mydriasis and/or miosis, repeatedly. They never decreased their pupil size less than 4 mm. The changes of pupil size were so slow that we could recognize them only after several hours or several days, and they were quite different from the light reflex. They did not receive any influences from turnover of day and night, darkness of the room, dopamine, etc. For the changes of pupil size were observed in the cases of organic brain death, it was elucidated that they were not due to the brain nerve activity. Then, it was considered that the changes of pupil size in the cases of functional brain death should be the same phenomena, because brain nerve function was lost.(ABSTRACT TRUNCATED AT 250 WORDS)