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Vegetative state

Patients in a vegetative state are awake but are unaware of self or of the environment [1, 2]. Jennett and Plum cited the Oxford English Dictionary to clarify their choice of the term "vegetative": to vegetate is to "live merely a physical life devoid of intellectual activity or social intercourse" and vegetative describes "an organic body capable of growth and development but devoid of sensation and thought".

Persistent vegetative state” has been arbitrarily defined as a vegetative state still present one month after acute traumatic or non-traumatic brain damage but does not imply irreversibility [3].

Permanent vegetative state” denotes irreversibility. The Multi-Society Task Force on PVS concluded that three months following a non-traumatic brain damage and 12 months after traumatic injury, the condition of vegetative state patients may be regarded as ‘permanent’ and therefore irreversible. However, these guidelines are best applied to patients who have suffered diffuse traumatic brain injuries and post anoxic events; other non-traumatic etiologies may be less well predicted [see for example 4, 5] and require further considerations of etiology and mechanism in evaluating prognosis. Even after these long and arbitrary delays, some exceptional patients may show some limited recovery. This is more likely in patients with non-traumatic coma without cardiac arrest, who survive in VS for more than 3 months.

It is very important to stress the difference between persistent and permanent vegetative state which are, unfortunately, too often abbreviated identically as PVS, causing unnecessary confusion [6]. When the term “persistent vegetative state” was first described [1], it was emphasized that persistent didn’t mean permanent and it is now recommended to omit “persistent” and to describe a patient as having been vegetative for a certain time. When there is no recovery after a specified period (depending on etiology three to twelve months) the state can be declared permanent and only then do the ethical and legal issues around withdrawal of treatment arise [7, 8].

The vegetative state can also be observed in the end-stages of some chronic neurodegenerative diseases, such as Alzheimer’s (howver recent studies show that most of these patients are rather minimally conscious), and in anencephalic infants.

The diagnosis of vegetative state is very unlikely when there is consistent and reproducible visual fixation or any degree of sustained visual pursuit – the diagnosis of a minimally conscious state then becomes much more likely. It is essential to establish repetitively the formal absence of any sign of conscious perception or deliberate action before making the diagnosis. Standardized clinical testing by means of validated scales such as the Coma Recovery Scale is recommended.

 

Table. Criteria for the vegetative state (US Multi-Society Task Force on Persistent Vegetative State guidelines)[3]

  • No evidence of awareness of self or environment and an inability to interact with others
  • No evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli
  • No evidence of language comprehension or expression
  • Intermittent wakefulness manifested by the presence of sleep-wake cycles
  • Sufficiently preserved hypothalamic and brainstem autonomic functions to permit survival with medical and nursing care
  • Bowel and bladder incontinence
  • Variably preserved cranial-nerve and spinal reflexes

References

1.         Jennett, B. and Plum, F. (1972). Persistent vegetative state after brain damage. A syndrome in search of a name. Lancet  1, 734-737.
2.         Jennett, B., The vegetative state. Medical facts, ethical and legal dilemmas. 2002, Cambridge: Cambridge University Press.
3.         The Multi-Society Task Force on PVS (1994). Medical aspects of the persistent vegetative state (1). N. Engl. J. Med.  330, 1499-1508.
4.         Menon, D.K., et al. (1998). Cortical processing in persistent vegetative state. Lancet  352, 200.
5.         Wilson, B.A., Gracey, F., and Bainbridge, K. (2001). Cognitive recovery from "persistent vegetative state": psychological and personal perspectives. Brain Inj  15, 1083-1092.
6.         Laureys, S., Faymonville, M.E., and Berre, J. (2000). Permanent vegetative state and persistent vegetative state are not interchangeable terms, 16 Oct 2000. British Medical Journal.
7.         Jennett, B. (2005). The assessment and rehabilitation of vegetative and minimally conscious patients: Definitions, diagnosis, prevalence and ethics. Neuropsychological Rehabilitation  15, 163-165.
8.         American Congress of Rehabilitation Medicine (1995). Recommendations for use of uniform nomenclature pertinent to patients with severe alterations of consciousness. Arch. Phys. Med. Rehabil.  76, 205-209.

Links

American Medical Association on Withholding or Withdrawing Life-Sustaining Medical Treatment

British Medical Association on Treatment decisions for patients in persistent vegetative state

World Medical Association Statement on Persistent Vegetative State