SeminarPersistent vegetative state
Section snippets
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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The nature of consciousness
2013, Handbook of Clinical NeurologyCitation Excerpt :It is conceivable that brainstem death might become a treatable disorder as neural prostheses are developed. At a theoretic level, it is open to question whether patients in vegetative states are wholly unaware (Zeman, 1997). The classic impairments of consciousness mentioned so far are relatively severe and well defined.
A Mental Ethnography: Conclusions from Research in LSD
2023, A Mental Ethnography: Conclusions from Research in LSDPrediction of Minimally Conscious State with Brain Stem Reflexes in Unconscious Patients after Traumatic Brain Injury
2019, Journal of Craniofacial Surgery