Brain Death and the Vegetative State

Kurt A Jellinger, Institute of Clinical Neurobiology, Vienna, Austria

Published online: April 2010

DOI: 10.1002/9780470015902.a0002212.pub2

Full Article on Wiley Online Library

Abstract

A brain‐dead patient is unconscious, has lost the capacity to breathe (apnoea) and requires mechanical respiration; even with full supportive treatment his heart will soon stop, usually only after a few days. The widely accepted definition of brain death (BD) equates it with death of a person and renders legally the removal of organs for transplantation. Evidence‐based criteria for the clinical diagnosis of BD and the use of confirmatory tests are available. A patient in the vegetative state is unconscious but has his eyes open and can breath on his or her own, but requires artificial feeding, automatic‐vegetative functions and some active functions of the severely damaged brain being preserved. Its diagnosis is based on repeated clinical observations and modern neuroimaging tests. Given adequate treatment persons in a vegetative state can survive for years and may recover towards the minimally conscious state or even can regain (in)complete recovery.

Key Concepts:

Brain death is the expression of irreversible loss of brain function.
Brain death is a precisely defined clinical diagnosis based on generally accepted criteria.
When the clinical diagnosis is unequivocal, no additional confirmatory tests (angiography, electroencephalography, transcranial Doppler sonography or magnetic resonance angiography) are necessary.
Causes of brain death are traumatic brain injury, cerebral haemorrhage and systemic hypoxia, and frequently associated with brain oedema and raised intracranial pressure damaging the brainstem.
The widely accepted legal definition of brain death equates it with death of a person.
Brain death diagnosis depends on adequate observation times (6–24 h or more), and its declaration has to be made by two adequately experienced physicians.
Unequivocal diagnosis of brain death generally renders legally the removal of organs for transplantation.
The vegetative state consists of continuing unconsciousness with no evidence of awareness and no possibility for communication, with the eyes open, spontaneous breathing and preserved brainstem autonomic functions.
Causes of the vegetative state are various types of severe acute brain damage (head injury, systemic hypoxia or encephalitis) or progressive brain damage (terminal states of Alzheimer or Huntington disease, demyelinating, metabolic, inflammatory diseases or severe malformations).
The diagnosis of the vegetative state depends on repeated clinical examinations and demands considerable skills; it can be supported by electroencephalography and modern neuroimaging methods showing severe drop of cerebral metabolism.
Given adequate treatment, persons in a vegetative state can survive for years and some may recover towards the minimal conscious state or may even show (in)complete recovery with various degrees of incapacity.

Keywords: coma; brain death; apnoea; vegetative state; acute brain damage; minimally conscious state

Article Title:	Brain Death and the Vegetative State
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	Figure 1. Cerebral lesion patterns in disorders of consciousness. (a) Diffuse lesion of the cerebral cortex (laminar necrosis). (b) Diffuse damage to the hemispheral white matter. (c) and (d) Lesions of the upper brainstem involving the ascending reticular system. (e) Lesions of the limbic system. (f) Lesions of the pontine basis (locked‐in‐syndrome). (g) Multiple cerebral lesions in various locations. (h) Diffuse anoxic panencephalopathy in BD.
	Figure 2. Conceptual overview of functional outcomes following severe brain injuries. Grey zone between vegetative state (VS) and minimally conscious state (MCS) reflects rare patients with fragments of behaviour that arise spontaneously and not in response to stimulation. By nosologic criteria, these patients remain in VS. The bold black line indicates emergence from the MCS, defined by reliable functional communication. Locked‐in syndrome is not a disorder of consciousness. Reproduced from Posner et al., with permission from Oxford University Press.
	Figure 3. Outcome for patients in a persistent vegetative state (PVS) after traumatic or nontraumatic injury. Reproduced from Posner et al., with permission from Oxford University Press.