Parts of the brain of a 12-year-old boy at the centre of a life-support treatment dispute have died and are decaying, a specialist has told a High Court judge.

The specialist told Mrs Justice Arbuthnot how tests showed that the lower part of Archie Battersbee’s brain stem was significantly damaged and the upper part was also damaged.

He said Archie’s prognosis was “very grave” and told the judge that the youngster’s chances of recovery were “very low”.

Doctors treating Archie at the Royal London Hospital in Whitechapel, east London, say life-support treatment should end.

Archie’s parents, Hollie Dance and Paul Battersbee, from Southend, Essex, disagree.

Lawyers representing the Royal London Hospital’s governing trust, Barts Health NHS Trust, have asked Mrs Justice Arbuthnot to decide what moves are in Archie’s best interests.

Mrs Justice Arbuthnot is overseeing a final hearing – due to end on Wednesday – in the Family Division of the High Court in London.

She had ruled at a recent hearing that Archie should undergo further scans before she made decisions.

The specialist, who cannot be named in media reports of the case, explained the results of recent brain and spine scans to the judge on Monday.

He said there had been no improvement, since earlier scans were taken in mid-April, but signs of deterioration.

Barrister Fiona Paterson, who is leading Barts Health NHS Trust’s legal team, asked the specialist if scans showed that parts of Archie’s brain and spinal cord had died and were decaying.

He replied: “Yes.”

And he told Mrs Justice Arbuthnot: “The chance of recovery is very low.

“I think Archie has sustained severe enough brain damage that a point of return is unlikely.”

Ms Paterson had earlier told the judge: “The scans, once they are interpreted, paint a picture that may be very hard to bear.”

Mrs Justice Arbuthnot has heard that Archie suffered brain damage in an incident at home in early April.

Ms Dance has told how she found him unconscious with a ligature over his head on April 7 and thinks he might have been taking part in an online challenge.

The youngster has not regained consciousness.

The specialist indicated that recent scans showed how Archie’s condition had worsened.

He added: “They show much more conspicuous and worse damage in areas that are very critical.”

Barrister Bruno Quintavalle, who leads Archie’s family’s legal team, told the judge that Archie’s heart was still beating.

He also there was an issue as to whether “the correct procedure” had been followed, and whether the “family’s views” had been taken into account.

The hearing continues.