Persistent vegetative state

The relative resilience of the brain stem allows it to survive injuries that may create irreversible damage to the cerebral hemispheres - then the patient will enter that state defined as "vegetative". Retrospectively, after post-mortem examination, it may be possible to identify massive neocortical damage which will indicate that the patient was permanently in the vegetative state,37 but there are no clinical or laboratory means of confirming this before post-mortem examination and therefore the term "persistent vegetative state" has been used clinically. Specialists in rehabilitation are concerned that physicians may take the attitude that there is no point in treating such patients, therefore creating a self-fulfilling prophecy of poor prognosis, no treatment, and poor outcome.38

There is continuing debate as to the potential for recovery for patients who are in a vegetative state. In patients who have suffered non-traumatic injuries such as anoxia and ischaemia, the prognosis for recovery from the vegetative state is poor after the first few weeks and almost negligible after 6 months.39,40 There are some reports of patients who suffered coma as a result of head trauma and in whom an improvement from the vegetative state has been recognised after months, but these anecdotal cases of recovery are difficult to validate and it seems possible that such patients were not truly vegetative but rather in a state of profound disability with cognition at the beginning of the observation.41-43

Investigations are of little help in identifying the vegetative state because many types of EEG pattern have been recorded from near normality to a flat record. CT scans usually show considerable cortical atrophy with ventricular dilatation after the disease has been present for some time. Somatosensory evoked responses are said to show loss of the cortical component, and positron emission tomography (PET) shows cortical metabolic underactivity. None is diagnostic in its results.44

Patients in a persisting vegetative state will often have received artificial ventilation at some time during their initial coma or resuscitation but they are not truly respirator dependent and, as they are able to breathe, are only dependent upon carers for the supply of liquid and nutrients, and the prevention of complications. The management of individual patients will depend upon circumstances, other aspects of the diagnosis, and consideration of prognosis.45 There is recent advice from the Royal Colleges in the UK9 and an international working party46 on the diagnosis and management of the permanent vegetative state and the involvement of the courts in the withdrawal of artificial hydration and nutrition. A recent review of the diagnosis of the permanent vegetative state and the law foresees potential problems in relation to human rights legislation.47-49

Management of medical coma

• The initial care for a patient in coma must be resuscitation by ensuring adequate oxygenation and circulation. A sample of blood should be withdrawn to estimate glucose and other parameters and, once stability is ensured, it is imperative to obtain an adequate history from those who brought the patient to the accident and emergency department or those who are responsible for the previous care.

• An assessment of the level of coma follows with an evaluation of those other features that may give clues to aetiology, including temperature, heart rate, blood pressure, pattern of respiration, abnormalities in the skin, and focal signs in the chest, abdomen, or limbs.

• Neurological examination must include a search for evidence of trauma, tests for meningism, examination of the fundi, assessment of the brain stem reflexes, and the identification of any focal abnormality in face or limbs.

• The relevant investigations may then be considered, including biochemical and serological assessments, drug levels, radiological imaging, and the possibility of EEG. Lumbar puncture will be indicated in certain circumstances and, with these investigations, the diagnosis of the aetiology of the coma should be established, corrective therapies instituted, and continuation of care and protection established.

• Most patients presenting to hospital in coma or lapsing into coma are ideally treated on an intensive care unit or a high dependency unit. The cause of the coma and the prognosis of the patient will determine their further follow up and the site of continuing care.

• After 6 hours of coma patients who do not show eye opening have only a 10% chance of making a good or moderate recovery.

• After one week of coma only 3% make a good or moderate recovery.

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