Elsevier

The Lancet

Volume 350, Issue 9080, 13 September 1997, Pages 795-799
The Lancet

Seminar
Persistent vegetative state

https://doi.org/10.1016/S0140-6736(97)06447-7Get rights and content

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Varieties of awareness

The words “awareness” and “consciousness” are used more or less interchangeably in a variety of senses (panel 1). They can refer: (a) to the waking state, (b) to the content of our experience from moment to moment, and (c) more generally, to our knowledge and intentions. Here are examples: (a) the patient is regaining consciousness, (b) I was conscious of a blinding light, (c) the Prime Minister is conscious that the nation has tired of her. In all three senses awareness is a matter of degree:

Definition

The term “persistent vegetative state” was chosen with care.1 Jennett and Plum cited the Oxford English Dictionary to clarify its meaning: to vegetate is to “live a merely phusical life devoid of intellectual activity or social intercourse” and vegetative is used to describe “an organic body capable of growth and development but devoid of sensation and thought”. The essence of the state Jennett and Plum were describing was “the absence of any adaptive response to the external environment, the

Pathology and pathophysiology

The vegetative state can result from any acute insult or chronic process which severely damages part or all of the cerebral hemispheres.17 The most common acute causes are head injury and hypoxic-ischaemic damage such as may follow cardiorespiratory arrest. It sometimes occurs as the end-stage of degenerative brain disorders, such as Alzheimer's disease.

Three main patterns of pathology are seen in the brains of patients who have died in a vegetative state23 (figure 3): (a) diffuse axonal

Epidemiology

We lack precise information on the prevalence of PVS. Estimates have ranged from 10 000 to 25 000 adults and 400–1000 children in the USA.17 There may be no more than 1000 patients with the PVS due to trauma in the UK.30

Prognosis

Figure 2 depicts the possible outcomes of a severe brain insult. The question which most concerns relatives and doctors caring for patients with vegetative state is whether a recovery is possible.

The prognosis one month after brain injury was analysed by the American Multi-Society Task Force on PVS in 1994.31 Three factors clearly influencing the chances of recovery were: age, aetiology, and time already spent in the vegetative state. The outlook is better in children, better after traumatic

Management

The first requirement for management is accurate diagnosis, coupled with an understanding of the natural history of PVS. Many patients entering a vegetative state emerge from it within a few weeks or months. Supportive early management is therefore usually appropriate.

So far no specific active treatment has been shown conclusively to increase the chances of recovering awareness. Sensory stimulation programmes,33 electrical brain stimulation,34 and pharmacological approaches35 all warrant

Conclusion

Consciousness is a complex concept because it incorporates wakefulness, our experience of ourselves and our surroundings, and the possession of knowledge and intentions. Wakefulness is particularly dependent on the brainstem, experience and volition on the cerebral hemispheres. Consciousness, in all its aspects, is a matter of degree

The vegetative state, a condition of “wakefulness without awareness”, is one outcome of severe brain injury. It is often misdiagnosed in patients who are, in fact,

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References (34)

  • B Jennett et al.

    Persistent vegetative state after brain damage

    Lancet

    (1972)
  • G Moruzzi et al.

    Brain stem reticular formation and activation of the EEG

    Electroencephalogr Clin Neurophysiol

    (1949)
  • A Cowey

    Current awareness: spotlight on consciousness

    Dev Med Child Neurol

    (1997)
  • AZJ Zeman et al.

    Contemporary theories of consciousness

    J Neurol Neurosurg Psychiatry

    (1997)
  • N Childs et al.

    Accuracy of diagnosis of the persistent vegetative state

    Neurology

    (1993)
  • K Andrews et al.

    Misdiagnosis of the vegetative state: retrospective study in a rehabilitation unit

    BMJ

    (1996)
  • AD Milner
  • P Stoerig et al.

    Blindsight in man and monkeys

    Brain

    (1997)
  • GG Gallup

    Chimpanzees: self-recognition

    Science

    (1970)
  • S Baron-Cohen

    Mindblindness: an essay on autism and theory of mind

    (1995)
  • F Plum et al.

    The diagnosis of stupor and coma

    (1980)
  • S Zeki

    A vision of the brain

    (1993)
  • D LaBerge

    Attentional processing

    (1995)
  • JL Barbur et al.

    Conscious visual perception without V1

    Brain

    (1993)
  • Medical aspects of the persistent vegetative state part I

    N Engl J Med

    (1994)
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