What does "brainstem death" mean? A review of international protocols.

Abstract

The term "brainstem death" is ambiguous; it can be used to refer either exclusively to loss of function of the brainstem or loss of function of the whole brain. We aimed to establish the term's intended meaning in national protocols for the determination of brain death/death by neurologic criteria (BD/DNC) from around the world. Of 78 unique international protocols on determination of BD/DNC, we identified eight that referred exclusively to loss of function of the brainstem in the definition of death. Each protocol was reviewed to ascertain whether it 1) required assessment for loss of function of the whole brain, 2) required assessment only for loss of function of the brainstem, or 3) was ambiguous about whether loss of function of the higher brain was required to declare DNC. Of the eight protocols, two (25%) required assessment for loss of function of the whole brain, three (37.5%) only required assessment for loss of function of the brainstem, and three (37.5%) were ambiguous about whether loss of function of the higher brain was required to declare death. The overall agreement between raters was 94% (κ = 0.91). There is international variability in the intended meaning of the terms "brainstem death" and "whole brain death" resulting in ambiguity and potentially inaccurate or inconsistent diagnosis. Regardless of the nomenclature, we advocate for national protocols to be clear regarding any requirement for ancillary testing in cases of primary infratentorial brain injury who may fulfill clinical criteria for BD/DNC.