A 17-month-old boy at the centre of a landmark right-to-life case has an "intolerable life", the high court heard today.

The boy, who can be named only as MB, suffers from spinal muscular atrophy - an incurable and progressively worsening condition that leads to complete paralysis.

The court heard that he cannot breathe for himself, cannot chew or swallow, is fed through a tube and, though he is not impaired mentally, can move only his eyebrows, feet and fingers, and these very slightly.

An unnamed hospital trust has asked Mr Justice Holman for permission to withdraw life-saving ventilation from the child because he has such a low quality of life.

It is believed to be the first time that such a move has been taken in the case of a patient who is sentient rather than in a persistent vegetative state.

His parents, from the north of England, want their son to live.

They say he can recognise and respond to them and enjoys spending time with his family, meaning that he has a reasonable quality of life.

A court order is in place preventing the identification of any of the parties in the action.

Questioned by Caroline Harry Thomas, counsel representing the child's interests, a Dr S told the court today: "One has to consider his inability to move and his inability to communicate effectively; his inability to express his wishes, his inability to show if he is in any pain or distress or, if he is, what is causing that.

"I think the cumulative effect of all of that is that he has an intolerable life."

The doctor predicted that over the next few months, the boy would be unable to open his own eyelids.

Another doctor, also designated as Dr S, described the boy as a "fragile" child who would die within minutes if ventilation were withdrawn.

He was referred to a video, seen by the judge, in which the child appeared to move his foot in response to his mother's request.

Dr S said he was very surprised by what he had seen, and neither he nor his medical colleagues had witnessed such a movement.

"He is a profoundly disabled child who will remain so, and there has not been any significant change to his condition," Dr S said.

The judge asked if Dr S would regard it as acceptable medically and ethically to continue ventilation but not to resuscitate, should the child go into collapse - as he did in October, when he was resuscitated and invasively ventilated.

The doctor replied: "I think the decision to continue specific treatment would not be in his best interests.

"I have been feeling that what I have been doing as a doctor has been wrong for many months, which is a very difficult position for me to be in.

"That is not just my opinion, but the opinion of many medical professionals who are directly involved in his care.

Dr S added that he would find it "difficult" if were asked to resuscitate the boy.

MB's mother has said: "We want our son to have a tracheotomy so we could take him home and give him a life instead of him being stuck in a hospital cubicle.

"We are very hopeful we can persuade the court that his quality of life is good enough so that treatment should not be withdrawn."