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Also see the separate article Coma.
Previously, the term persistent vegetative state (PVS) was used to describe all patients with prolonged disorders of consciousness. PVS has become marked by ethical and medical dilemmas, often, if not always, requiring legal assistance. There are now several cases where patients diagnosed as being in PVS have subsequently regained consciousness. This has led to outrage, especially if decisions were made to terminate hydration and nutrition. This has resulted in tension between carers and healthcare professionals in these situations.
It has, however, become increasingly clear that patients with altered levels of consciousness can exhibit varying levels of awareness. As such, an umbrella term called 'prolonged disorders of consciousness' (PDOC) has been defined by the Royal College of Physicians (RCP) and encompasses patients who have had impaired consciousness of over four weeks in duration.
The RCP in their latest guidance defines two distinct disorders under the heading of PDOC:
- Vegetative state - the patient is awake but does not exhibit awareness of their surroundings.
- Minimally conscious state - the patient is awake and has minimal awareness of their surroundings.
Coma is a profound state of unconsciousness. The individual is alive but unable to move or respond to the environment. The patient fails to respond to stimuli and will not display a normal sleep-wake cycle. Both the vegetative state and minimally conscious state may follow a coma.
There is loss of ability to think and of awareness of surroundings, but non-cognitive function and normal sleep patterns remain. Although they lose their higher brain functions, other key functions such as breathing and circulation remain relatively intact. Spontaneous movements may occur, and the eyes may open in response to external stimuli. They may occasionally grimace, cry, or laugh. They do not speak and they are unable to respond to commands. There is no swallowing reflex and no control over bowels or bladder. This differs from brainstem death where there is loss of all brain function including the ability to breathe spontaneously.
Minimally conscious state
The patient has altered consciousness which is usually severe but there are aspects of awareness which are present, albeit inconsistently.
Criteria for diagnosis
The following preconditions apply:
- The cause of the condition should be established as far as is possible. This may include acute cerebral injury, degenerative conditions, metabolic disorders, infections or developmental malformations.
- All potential reversible causes have been excluded - eg, persisting effects of sedative drugs, including anticonvulsants, anaesthetic or neuromuscular blocking agents.Other reversible causes might include metabolic disturbances and treatable structural lesions.
- Careful and full assessment by a trained specialist in the correct environment using the appropriate criteria.
Diagnosing a vegetative state
The following must be present for a diagnosis:
- No awareness of self or environment.
- No purposeful behaviours.
- No comprehension or significant expression.
There may, however, be some spontaneous movements (eg, shedding tears) or reflexive movements (eg, corneal reflex) and a number of other features as listed in the guidance.
Diagnosing a minimally conscious state
The diagnosis requires the presence of some cognitive capacity and awareness of self or the environment. The awareness must be in the form of certain behaviours listed in the guidance - eg, reaching for something or smiling in response to visual stimuli. These may be inconsistent (but reproducible) or sustained.
- People with lifelong severe disabilities, with severe intellectual disabilities, often with severe physical disabilities, have limited ability to respond to surroundings. Carers insist that they do communicate and are aware. They should not be classified as vegetative.
- Locked-in syndrome usually results from a brainstem stroke which abolishes voluntary control of movement without affecting either wakefulness or awareness. These patients are substantially paralysed but conscious, and can communicate using movements of the eyes or eyelids.
- Coma is unconsciousness in which the eyes are closed and sleep-wake cycles absent. Coma is usually transient, lasting for hours or days, and a vegetative state is a possible outcome.
- Death confirmed by brainstem death testing, implies the irreversible loss of all brainstem functions so that breathing is not spontaneous and the circulation is unstable. It is followed by cardiac arrest, usually within hours or days, despite intensive care.
Confirmation of the diagnosis
- Causes of error include confusion about the meaning of the various definitions, inadequate observation in suboptimal circumstances, failure to consult those who see most of the patient (especially family members), and the inherent difficulty of detecting signs of awareness in patients with major perceptual and motor impairments.[4, 5]
- Patients should be transferred and managed by units specialising in PDOC.
- The patient should be examined by at least two doctors who are expert in assessing disorders of consciousness. They should take into account the views of the medical staff, other clinical staff including clinical neuropsychologists, occupational therapists and physiotherapists, carers and relatives about the patient's reactions and responses. They should make their clinical assessments separately and write the details in the notes. They should consider the investigations which have been performed to confirm the cause of the condition. As the patient's physical position can affect responsiveness, it may be valuable to assess the patient in more than one position. It may be helpful for nursing staff and relatives to be present during the examination.
- If there is any uncertainty about the diagnosis, it should not be made and the patient should be reassessed at a later date. There is no hurry.
- Tools are available to help the assessment - eg, the Wessex Head Injury Matrix.
- Structured observation may help to reveal signs of awareness in doubtful cases. The key consideration in making the diagnosis is whether the patient might be aware to some degree. It is always important to seek the views of nursing staff, relatives and carers.
PVS can be diagnosed once the vegetative state has been present for >6 months in the case of anoxic or metabolic brain injury and >1 year if there was traumatic brain injury.The diagnosis of a permanent minimally conscious state is more difficult but becomes more likely after five years of a continuing minimally conscious state.Use of the term 'permanent' is taken to mean that recovery is unlikely. These states require continual monitoring.
The British Medical Association (BMA), in addition to the above guidance, mentions that decisions to withdraw or withhold treatment should not be made until the patient has been insentient for over 12 months.
- PDOC states should be diagnosed with care and should not be rushed. During this diagnosis period patients should receive full medical care - eg, artificial nutrition, and surgery if needed.
- Nursing care is important in order to avoid complications.
- PDOC patients should be reviewed for pain and depression regularly.
- Adequate nutrition often requires a percutaneous endoscopic gastrostomy (PEG) tube. Good skin care, passive joint exercises to minimise contractures, suction where necessary to help avoid aspiration, careful management of the incontinent bladder and bowel, and attention to oral and dental hygiene are all required.
- In those who regain consciousness, an early intensive neurorehabilitation programme may be beneficial.
- There is insufficient evidence presently for the use of medications (eg, dopaminergic medications) and decisions should be based on the patient's best interests.
- Deep brain stimulation has been used to attempt to wake patients from a vegetative or minimally conscious state but the value is uncertain.
Making treatment decisions
- In all reviews of treatment, the basis of the 'patient's best interests' should govern decisions. However, it is good practice to involve the key family members, carers, and staff who interact with the patient on a daily basis and the patient's general practitioner.
- Formal documentation of the lack of capacity in the medical notes.
- An independent mental capacity advocate is required if there are no family members or carers or where they are deemed not suitable (the reasons for the latter should be clearly documented).
- A formal review should occur and then the implications should be discussed with relatives and they should have time to consider the implications, including the possibility of withdrawing artificial feeding and hydration. In England and Wales, the decision has to be referred to a court. In Scotland, it is not compulsory but it may be prudent.
- A decision to withdraw other life-sustaining medication, such as insulin for diabetes, may also need to be referred to the courts because the legal position is uncertain, but the decision not to intervene with cardiopulmonary resuscitation, antibiotics, dialysis or insulin can be taken clinically, in the best interests of the patient, after full discussion with those concerned.
- Where there is an advance directive this must be respected. If not, efforts should be made to establish what the patient's views and preferences might have been, to help to make a decision in his or her best interests.
- It is impossible ever to be certain that a patient is wholly unaware, although the evidence suggests this. It is still reasonable to administer sedation when hydration and nutrition are withdrawn, to eliminate the possibility of suffering, however remote. The normal standards of palliative care should be observed.
- The guidance refers to adults but it is probably applicable to older children too. The position with regard to younger children is more difficult both clinically and emotionally.
The prognosis is influenced by age, the underlying cause and its current duration. A little over half of those in a vegetative state one month after trauma will regain awareness. With other causes, after a month in a vegetative state fewer than 20% will recover. The chances of regaining awareness fall as time passes. Beyond one year following trauma, and beyond six months in non-traumatic cases, the chances of regaining consciousness are extremely low. In the very small number of well-documented cases, recovery has usually been to a state of exceptionally severe disability.
Caring for carers
Patients with PDOC may be in a nursing home or a hospital. Those who love them will have enormous emotional needs that they may take to the general practitioner. It is important to understand the nature of the condition to be able to explain and empathise.
Future areas of research
- Further imaging techniques may help to determine how consciousness is produced and regulated.
- It is also important to determine whether patients in PDOC experience pain, and functional imaging may also be of help in this area.
- There is consideration for the role of post-mortems in confirming the diagnosis - for epidemiological purposes. This may also provide some insight into how to diagnose the condition at an earlier stage.
- Some studies have reported short-lived improvements in consciousness in PVS patients, with levodopa or zolpidem, but as mentioned above there is insufficient evidence and their use should be based on the patient's best interests.[11, 12]
- Improved assessment scales to look at the degree of awareness and to determine appropriate rehabilitation programmes..
Some ethical and legal history relating to persistent vegetative state
- The PVS has been under a lot of media and public scrutiny. This began with the case of Tony Bland in 1992-1993, a victim of the Hillsborough football disaster. The decision to discontinue artificial hydration and nutrition was made by the House of Lords. Following this, the BMA recommended that no decision to withdraw or withhold therapy should be made within the first 12 months.
- The USA's case of Terri Schiavo has also received a lot of medical, ethical, legal and political attention. The dilemma here centred mainly around the removal of artificial nutrition and hydration. There was a difference in opinion amongst her parents and her husband. The case went on for seven years in the legal house. It highlighted the importance of not only treating the patient but also of considering the needs of carers and family.
As medical technology advances at a rapid pace, the ability to sustain patients who have irreversible brain damage will improve. We will no doubt have further similar cases to ponder and debate. However, whether the medical, pathological, ethical and legal issues will ever be resolved completely still remains a mystery.
Further reading and references
; Legal consequences and ethical dilemmas of pain perception in persistent J Health Law. 2003 Fall36(4):523-48.
; Royal College of Physicians, 2003
; Royal College of Physicians (2013)
; Misdiagnosing the vegetative state after severe brain injury: the influence of medication. Brain Inj. 2004 Feb18(2):213-8.
; Accuracy of diagnosis of persistent vegetative state. Neurology. 1993 Aug43(8):1465-7.
; Misdiagnosis of the vegetative state: retrospective study in a rehabilitation unit. BMJ. 1996 Jul 6313(7048):13-6.
Withholding and Withdrawing Life-prolonging Medical Treatment 3rd edition; BMA, 2007
; Children and young adults in a prolonged unconscious state due to severe brain injury: outcome after an early intensive neurorehabilitation programme. Brain Inj. 2005 Jun19(6):425-36.
; DBS therapy for the vegetative state and minimally conscious state. Acta Neurochir Suppl. 200593:101-4.
; Chronic disorders of consciousness. Lancet. 2006 Apr 8367(9517):1181-92.
; What is it like to be vegetative or minimally conscious? Curr Opin Neurol. 2007 Dec20(6):609-13.
; Levodopa treatment for patients in persistent vegetative or minimally conscious states. Neuropsychol Rehabil. 2005 Jul-Sep15(3-4):414-27.
; Drug induced arousal from the permanent vegetative state. NeuroRehabilitation. 200621(1):23-8.
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