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vegetative state

vegetative state This defines the behaviour of a person in whom brain damage has put out of action the cerebral cortex — the thinking, feeling part of the brain — but without any lasting effect on the brain stem. The intact brain stem ensures that there are long periods of eye opening (unlike coma) and that there is spontaneous breathing (unlike brain death): these are important distinctions, since the three conditions are not infrequently confused by the media when reporting these tragic stories.

With the cerebral cortex either destroyed or disconnected there is no evidence of a working mind — no psychologically meaningful responses to the person's surroundings. No command is obeyed, no single word is uttered, and there is no evidence of awareness. The patient is therefore unconscious although ‘awake’ and with several reflex responses and activities. During the periods of eye opening the eyes may rove around randomly, and they may turn briefly with the head towards a sudden loud noise, when there may also be blinking and sometimes stiffening of the whole body. In some vegetative patients the eyes may briefly focus on an object and follow it when it moves. There are often chewing movements and there may be yawning — less often, brief smiling or weeping, but not in response to any appropriate situation. In response to a painful stimulus the spastic limbs may bend or straighten and the face may grimace. Inexperienced staff and family members are apt to interpret some reflex activity as evidence of meaningful responsiveness, when prolonged and careful observation fails to confirm this. However, the observations of family and carers are always taken seriously because they may be reporting the first signs of recovery from the vegetative state.

The vegetative state may result from an acute brain insult — the commonest causes being severe head injury or failure of the oxygen supply to the brain. This failure can follow cardiac arrest or respiratory obstruction (from strangulation, suffocation, or near drowning), when resuscitation has been in time to save the heart and the brain stem but too late for the more vulnerable cerebral cortex. These acute insults usually lead to coma for 2–3 weeks before the patient ‘wakes’ to the vegetative state. Some patients with progressive degenerative brain disease, such as Alzheimer's disease, gradually become vegetative after years of deterioration, and some infants with severe congenital abnormalities of the brain, or with chromosomal defects, can become vegetative.

Diagnosis depends on careful clinical observation over many weeks, because there are no laboratory or imaging tests that reliably indicate that a patient is vegetative. Sometimes a patient is mistakenly believed to be in a vegetative state when subtle signs of responsiveness have been overlooked. It is particularly important to be sure that there has not been localized damage to the brain stem with sparing of the cortex, resulting in the ‘locked-in syndrome’. In this, the patient is totally paralysed and speechless but is fully conscious; communication may be established using a yes/no code by eye blinks or movements — using the only muscles not paralysed.

Patients are said to be in a continuing or persistent vegetative state if there is no recovery after one month. Many of them die from respiratory complications over the next few months; some recover consciousness, while the rest remain vegetative. The longer the vegetative state lasts the less likely is there to be recovery of consciousness, and the less likely is there to be a reasonable recovery of other functions even if consciousness is regained. Those who become conscious after many months in a vegetative state are usually left paralysed and totally dependent, sometimes continuing to need tube feeding and not regaining speech. Patients who become vegetative after an episode of cerebral hypoxia very seldom show any recovery after three months, but after head injury some recovery may still occur up to twelve months after injury. After these periods it is usual to declare the vegetative state permanent.

Patients who survive for a year in the vegetative state are often quite stable and can survive for many years if tube feeding is continued and infections treated with antibiotics. Some have lived for 20–40 years. It has been argued by doctors, philosophers, and lawyers in several countries that continued survival in this state is not of benefit to the patient — a view often, but not always, shared by the relatives. If that is so then there is no moral or legal obligation to continue the medical treatment of artificial nutrition and hydration. In the USA and several European countries a decision to withdraw such treatment can be made by doctors after consultation with the family, but in the UK permission has to be sought from the High Court.

Bryan Jennett

Bibliography

Jennett, B. (2001). The vegetative state: medical facts, ethical and legal dilemmas. Cambridge University Press.
Jennett, B. and and Plum, F. (1972). Persistent vegetative state after brain damage. A syndrome in search of a name. Lancet, 1, 734–7.


See also artificial feeding; brain death; brain stem; coma.

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Vegetative State

Vegetative State

Definition

A coma-like state characterized by open eyes and the appearance of wakefulness is defined as vegetative.

Description

The vegetative state is a chronic or long-term condition. This condition differs from a persistent vegetative state (PVS, a state of coma that lacks both awareness and wakefulness) since patients have awakened from coma, but still have not regained awareness. In the vegetative state patients can open their eyelids occasionally and demonstrate sleep-wake cycles. They also completely lack cognitive function. The vegetative state is also called coma vigil.

Causes and symptoms

The vegetative state can be caused by:

  • cardiac arrest
  • prolonged and profound hypoglycemia (an abnormal and severe decrease in blood sugar)
  • carbon monoxide poisoning
  • head injury
  • brain hemorrhage
  • compression of the brainstem
  • tumors
  • bilateral hemispheric demyelination (a loss of nerve cells)
  • injury of the brain following infections (meningitis or encephalitis)
  • neurodegenerative diseases
  • anencephaly (an abnormality of the brain and skull)
  • diffuse nerve cell injury

Patients in a vegetative state apparently have functioning of a special area in the brain called the reticular activating system (RAS) responsible for sleep-wake cycles. The connections that integrate more complex abilities such as awareness are interrupted. Patients in the vegetative state can open and close eyes spontaneously. They may appear to track or follow objects with their eyes. Patients may chew and swallow food placed in the mouth. The vegetative patient does not respond to sound, hunger, or pain. Patients cannot obey verbal commands and lack local motor responses. Additionally these patients cannot talk in comprehendible terms and they may become noisy, restless, and hypermobile. These patients are in a state of arousal but completely lack awareness.

Diagnosis

Diagnosis of vegetative state depends on the primary cause of brain dysfunction. A comprehensive history and neurological examination, neuroimaging studies, and chemical analysis of the blood are essential. Additionally, special tests such as cerebrospinal fluid (CSF, the fluid that bathes and nourishes the brain and spinal cord) analysis and electroencephalography, (EEG analyzes the electrical activity within the brain) may be indicated to establish a diagnosis.

Treatment

Treatment is directed to presenting symptoms and patient needs. Patients require constant monitoring and assistance with feeding, hydration hygiene, assisted movement (to help prevent ulcers and blood clots in the legs), and elimination of waste products.

Alternative treatment

There is no known alternative treatment for vegetative patients.

Prognosis

The prognosis is generally poor and the condition can persist chronically.

Prevention

There is no known prevention since this state can occur as a result of unavoidable situations such as an accident, tumor, and bleeding or genetic abnormality.

KEY TERMS

Cognitive The ability (or lack of) to think, learn, and memorize.

Hypermobility Increased movement of joints.

Resources

BOOKS

Goetz, Christopher G., et al, editors. Textbook of Clinical Neurology. 1st ed. W. B. Saunders Company, 1999.

Goldman, Lee, et al. Cecil Textbook of Medicine. 21st ed. W. B. Saunders Company, 2000.

Miller, Ronald D., et al, editors. Anesthesia. 5th ed. Churchill Livingstone, Inc., 2000.

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vegetative state

vegetative state
1. A stage in the life cycle of a plant when reproduction proceeds asexually by detachment of some part of the plant body and its subsequent development into a complete plant.

2. The noninfective state in a phage during which the genome multiplies actively and controls the synthesis by the host (a bacterial cell) of the materials necessary for the production of infective particles (i.e. more phages and phage DNA). These are released by lysis of the host cell.

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"vegetative state." A Dictionary of Plant Sciences. . Encyclopedia.com. 23 Oct. 2017 <http://www.encyclopedia.com>.

"vegetative state." A Dictionary of Plant Sciences. . Encyclopedia.com. (October 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/vegetative-state-0

"vegetative state." A Dictionary of Plant Sciences. . Retrieved October 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/vegetative-state-0

vegetative state

vegetative state
1. A stage in the life cycle of a plant when reproduction proceeds asexually by detachment of some part of the plant body and its subsequent development into a complete plant.

2. The non-infective state in a phage during which the genome multiplies actively and controls synthesis by the host (a bacterial cell) of the materials necessary for the production of infective particles (i.e. more phages and phage DNA). These are released by lysis of the host cell.

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"vegetative state." A Dictionary of Ecology. . Encyclopedia.com. 23 Oct. 2017 <http://www.encyclopedia.com>.

"vegetative state." A Dictionary of Ecology. . Encyclopedia.com. (October 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/vegetative-state

"vegetative state." A Dictionary of Ecology. . Retrieved October 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/vegetative-state