One in five patients believed to be in a vegetative state could be conscious and locked in unresponsive bodies, experts have warned.
A group of scientists have criticised guidelines for their care in hospitals and nursing homes, arguing they fail to recommend using brain-scanning technologies to detect consciousness.
They predict thousands of patients with prolonged disorders of consciousness (PDOC) – who are thought to have no brain activity – are actually aware of their surroundings.
And they say current guidelines, which have been set by the Royal College of Physicians (RCP), are 'indefensible'.
The claims have been made by a neurologist, a neuroscientist and a lawyer-ethicist.
Scientists say thousands who are in a vegetative state are aware of surroundings. Past studies showed MRI scans can detect consciousness in some patients (stock image)
Previous studies have shown that using MRI scans or bedside electroencephalogram – a monitoring tool using electrodes – can detect consciousness in some patients thought to have no awareness of what is going on around them.
Techniques include asking them to visualise people or objects, which activate different areas of the brain, or by analysing whether their brain patterns while watching a film match those measured in fully conscious audiences.
RCP guidelines, published last year, read: 'The overwhelming consensus of clinical commentary and peer review is that more advanced brain imaging and electrophysiology techniques have provided valuable insights into this patient group, and will continue to provide an important focus for research.
'However, the evidence base has not yet reached a stage of development where these could be considered to be part of routine clinical practice'.
Comparable guidelines in the US agree that the research is at an early stage, but recommend advanced scans in certain circumstances, including where there is 'continued ambiguity regarding evidence of conscious awareness' despite multiple assessments.
The three experts, professors Neil Scolding, from the University of Bristol, Adrian Owen, of Western University in Canada, and John Keown, from Georgetown University in the US, say there may be up to 25,000 UK patients with PDOC.
Experts criticised guidelines for care of patients in a vegetative state in hospitals, arguing they fail to recommend using brain-scanning technologies to detect consciousness (stock image)
In a letter to the Times, they write: 'Remarkable research using neuroimaging has shown that about 20 per cent of patients labelled as PDOC are in fact fully, or at least partly, conscious.'
They say the RCP's position is indefensible and needs 'urgent review' on scientific, ethical and legal grounds.
It could even help determine whether they have the mental capacity to make decisions about their care.
The RCP's PDOC guideline development group said: 'This is an evolving area of medicine which is continuously under review.'
It said the existing evidence base did not yet support the idea that the scans offered added value 'over and above the much more extended clinical evaluation and monitoring that is available in the UK compared to other countries'.