"They are normal human beings. All their senses are intact, so they can feel and see ... they just can't move."
That's the description of locked-in syndrome, a condition frequently brought on by strokes, as explained by Dr Graeme Hankey, a consultant neurologist and head of the stroke unit at Royal Perth Hospital (RPH), Western Australia.
Locked-in syndrome sufferer Tony Nicklinson, 57, who overnight failed in his bid to Britain's High Court to legally end his life, has described his life following a 2005 stroke that left him unable to speak or move below his neck as "a living nightmare".
Dr Hankey said the condition is "not common" and about two or three of the 600 stroke victims admitted to his hospital each year have locked-in syndrome.
But the condition, while rare, has no cure. What medical professionals and caregivers can do is to give patients the best nursing and rehabilitation possible so "they can be kept alive and realise the potential for spontaneous recovery", he said.
"You don't need a test. You just need to assess the person at the bedside," Dr Hankey said about how doctors look for locked-in syndrome.
"You can say to them, 'Can you lift us your arms, legs, can you say anything, can you move your eyes, can you feel me?'. Often they can't communicate with you but they can communicate by moving their eyes or just blinking. So you say blink twice for yes or once for no."
The most common cause of locked-in syndrome is a stroke, which results from a blocked blood vessel into the brain stem called the basilar artery. The stroke "takes out" the front of the brain stem, where your motor output comes from, he said.
If the medical professional has seen the patient within 4½ hours of their stroke, they can be given clot-busting treatment to restore the blood flow. If the doctor sees the patient after that time period, "all you can do is to try and prevent any further propagation of the clot with anti-plater drugs like aspirin", Dr Hankey said.
The key to helping locked-in syndrome patients improve their chances of recovery is nursing and rehabilitation.
"For a start you have to be cognisant that they are a normal human being. They just can't move," Dr Hankey said.
"You've got to be very careful what you say, because some people think that they are unconscious and talk about them as if they are not there. But they can see and feel. They want to scratch. They want to empty their bladder.
"We had one person who couldn't even move their eyes but you could tell by their pupils constricting or dilating if they were experiencing pain. You try to work out a way to communicate with them," he added.
Dr Hankey said many locked-in syndrome patients die from immobility complications such as pneumonia, urine infections or from skin infections through pressure sores.
But with "very good nursing care they can be kept alive and realise the potential for spontaneous recovery", he said.
And some people do get better, although a complete recovery is uncommon, Dr Hankey said.
Former British police officer and teacher Richard Marsh told The Guardian last week of his silent struggle to survive after suffering a massive stroke in 2009.
"The doctors would just stand at the foot of the bed and just talk like I wasn't in the room. I just wanted to holler: 'Hey people, I'm still here!'," he told the newspaper.
Four months and nine days later, he walked out of his long-term care facility after recovering 95 per cent of his functions.
Another sufferer of locked-in syndrome, Peter Coghlan, said he walked out of the Shenton Park Rehabilitation Centre at RPH six months after he suffered a massive stroke.
But for Mr Nicklinson, who plans to appeal the High Court judgment, the rejected bid means "yet another period of physical discomfort, misery and mental anguish while we find out who controls my life - me or the state".
A second victim of the syndrome, "Martin", who also lost his challenge, said in a statement through his lawyer that he was "even more angry and frustrated".
"My life following my stroke is undignified, distressing and intolerable. I wish to be able to exercise the freedom which everyone else would have - to decide how to end this constant tortuous situation," he said.