The parents of an 18-month-old boy with a terminal muscle-wasting disease, won a High Court legal battle to stop doctors turning off the ventilator keeping him alive.

The ruling comes despite the belief of doctors that his life is so intolerable that he should be allowed to die.

The boy was born with spinal muscular atrophy, an incurable and degenerative muscle wasting disease that eventually causes total paralysis.

He is unable to make any sound, breathe or swallow on his own, is fed through a tube and has to undergo several painful procedures every day to keep him alive.

He is only able to move his eyebrows, feet, and fingers very slightly.

Judge Justice James Holman heard that 10 consultants on the unit, along with three independent experts, all agreed that the boy should be allowed to die.

But his parents who have two other children aged four and five, disagreed and insisted their son does have a quality of life and told the court he enjoys being read to and listening to songs.

His parents say the boy still enjoys the company of his family and was not mentally impaired.

The judge described the life of the boy as helpless and sad, the boy is expected to die within a year; but he rejected the doctors’ request to turn off the ventilator as he felt it was not at this time, in the best interests of the boy to discontinue ventilation.

The landmark case is believed to be the first in which doctors had asked to allow a patient who is physically disabled but not mentally impaired or in a persistent vegetative state to die.

Although siding with the boy’s parents on the main issue in the case, the judge also said he could not endorse other medical treatment which could inflict additional pain on the baby.

The judge said at that point it would be in his best interests then to withhold those procedures even though he would probably die.

Charities and anti-euthanasia groups have welcomed the ruling, saying it had stopped a trend “down a dangerous slope” towards a policy of withholding life-saving treatment from severely disabled people.

The Royal College of Paediatrics and Child Health said the ruling helped clarify what should be done in “incredibly rare and difficult cases”.