[Do we defend a brain oriented view of death?]. / ¿Defendemos una visión encefálica de la muerte?

AIMS: To propose a new formulation of death based on the mechanisms involved in consciousness generation in human beings. DEVELOPMENT: Any complete formulation of death must include three different elements: a definition of death, its anatomofunctional substratum and the tests required to diagnose death. The three brain oriented formulations of death are: the whole brain, the brain stem, and the neocortical formulations of death. In this paper I review and discuss each of these formulations, and I propose a new formulation about human death based on the physiopathological mechanisms involved in the generation of consciousness. This contains two physiological components: arousal and awareness. Since the structures of the brain stem, the diencephalon and the cerebral cortex interact to generate consciousness, it would be a mistake to make a rigid distinction between their functions from the point of view of waking and content. Important interconnections between the brain stem, other subcortical structures and the neocortex give rise to both components of consciousness. The generation of consciousness, then, is based on the anatomy and the physiology of pathways throughout the whole brain. None of the three formulations above is wholly satisfactory. CONCLUSION: I propose a new formulation of death that identifies consciousness as the most important function of the organism, because it provides the essential human attributes and the highest level of control within the hierarchy of integrating functions of the organism

¿Defendemos una visión encefálica de la muerte? / Do we defend a brain oriented view of death?

Objetivo. Proponer una nueva formulación de la muerte según los mecanismos de generación de la conciencia en el ser humano. Desarrollo. Toda formulación completa sobre la muerte debe incluir tres elementos diferentes: una definición de la muerte, su sustrato anatomofuncional y las pruebas requeridas para diagnosticar la muerte. Las tres formulaciones sobre la muerte, orientadas hacia el encéfalo, son: la muerte de todo el encéfalo, la del tronco encefálico y la formulación neocortical de la muerte. En este artículo, se revisa y critica cada una de estas formulaciones, y se propone una nueva formulación sobre la muerte humana, basada en los mecanismos fisiopatológicos de la generación de la conciencia. Ésta posee dos componentes fisiológicos: el despertar y el contenido. Como las estructuras del tronco encefálico, diencéfalo y corteza cerebral interactúan para generar la conciencia, cualquier distinción rígida entre sus funciones desde el punto de vista del despertar y del contenido sería un error. Importantes interconexiones entre el tronco encefálico, otras estructuras subcorticales y la neocorteza generan ambos componentes de la conciencia. Por tanto, la generación de la conciencia se basa en la anatomía y la fisiología de vías a lo largo de todo el encéfalo. Ninguna de las tres formulaciones previas es totalmente satisfactoria. Conclusión. Se propone una nueva formulación de la muerte que identifica a la conciencia como la función más importante del organismo, porque provee los atributos humanos esenciales y el nivel de control más alto, en la jerarquía de las funciones integradoras del organismo (AU)

[Usefulness of multimodal evoked potentials and the electroretinogram in the early diagnosis of brain death]. / Utilidad de los potenciales evocados multimodales y del electrorretinograma en el diagnóstico precoz de la muerte encefálica.

INTRODUCTION AND METHODS: We studied 72 patients fulfilling all the criteria for brain death (BD) by means of a series of tests: brain stem auditory visual evoked potentials (VEP), short latent period somatosensory evoked potentials (SEV) and electroretinogram (ERG). RESULTS: Three characteristic PEATC patterns were identified: bilaterally flat (73.34%), bilateral I wave (16.66%) and unilateral I wave (10%). The N20 wave of the SEV and other later cortical components were not seen in any patients, whilst the so-called subcortical components were partially or totally maintained. The use of non-cephalic data permitted discussion as to the origin of the subcortical components. When cephalic data was used to obtain the ERG and the VEP, the a and b waves of the ERG were recorded in all cases, whilst in the VEP channel waves of inverse polarity appeared of similar morphology and the same latency, but of lower amplitude than those of ERG. When a non-cephalic reference was used, the morphology and latency of the ERG components were unchanged, whilst no response was obtained from the VEP channel. This electrophysiological pattern indicates that the only part of the visual pathway of patients with BD to maintain electrical activity is the retina. CONCLUSION: The application of this set of tests permits early diagnosis of BD, which is basic for transplantation.

[A new formulation of death: definition, criteria and diagnostic tests]. / Una nueva formulación de la muerte: definición, criterio y pruebas diagnósticas.

OBJECTIVE: To present a new formulation of human death based on neurological considerations. DEVELOPMENT: One of the reasons there is still controversy over a new formulation of human death which is acceptable to society, is that many authors do not suitably integrate three fundamental aspects which should be included in such a formulation: definition, criteria and diagnostic tests. We review the physiopathological mechanisms for generation of consciousness and discuss the three fundamental criteria presented by different authors in recent decades: the whole encephalum, brainstem death and neocortical criteria. We conclude that there are major contradictions in the three criteria with regard to satisfactory integration of the elements, definition, criteria and diagnostic tests. We therefore present a new formulation of human death. DEFINITION: irreversible loss of consciousness, since this gives the essential human attributes, and is the most integrating function of the organism. CRITERIA: cortico-subcortical connections for the generation of both components of consciousness (capacity and content). DIAGNOSTIC TESTS: no waking response to stimuli (capacity), no cognitive nor affective functions (content). CONCLUSIONS: We present a new formulation of human death on a neurological basis which permits satisfactory integration of the three fundamental elements, definition, criteria and diagnostic tests, and so offers a suitable starting point from which man may start to understand death.

Capablanca's stroke: an early case of neurogenic heart disease. Cuban-world-champion of chess 1921-1927.

The great chess master Jose Raul Capablanca died of a stroke in New York city in 1942. An analysis of his death is instructive in the discussion of cardiac repercussions of hypertensive cerebral hemorrhage, particularly regarding the close relationship between subendocardial hemorrhage and its probable source - sympathetic activation - caused by stroke.