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 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.
