The mother of a youngster who suffered a mystery childhood stroke today spoke of her devastation at learning her son has a rare brain disease.

Little Jacob Jackson suffered the debilitating stroke two weeks before his third birthday, but parents Liz and Garry had no idea what had caused it.

An MRI scan at Leeds General Infirmary showed his brain was peppered with blood clots. Doctors told Liz that Jacob's brain was unexpectedly deteriorating and an angiogram confirmed the middle cerebral artery was badly diseased.

Jacob's mother revealed how the four-year-old from Liversedge and his sister Molly, five, who suffers fits, now make a heart-breaking prayer every night.

"Every night, Molly and Jacob say their prayers and ask for their brains to get better," said Liz. "If I could look ten years into the future, I would just ask for him still to be here - that is my biggest worry at the moment and it frightens me to death.

"We were absolutely gutted when they told us this disease had caused the stroke," said Liz, 25. "The disease is so rare that doctors have never seen anything like it and it has no name. It was hard enough to cope after his stroke because of how it left him, but then to be hit with this news was unbelievable."

On Thursday, Jacob and his parents will travel to Southampton to see a specialist neurologist from Great Ormond Street Children's Hospital. His case is so rare she has discussed it with doctors in America.

"He will probably go to Great Ormond Street for more in-depth scans and treatment," said Liz. "There has been talk of giving Jacob anti-cancer drugs and brain surgery is still in the pipeline.

"The part of the brain that is diseased is the one that controls thirst and temperature, so in the middle of the night we have to cool him down or get him a drink."

To add to the family's heartache, Molly has begun having fits and has also had to have a brain scan.

"Molly had one fit a week, for six weeks," said Liz. "We have only just found out that her brain is okay, but she still has fits. We don't know if she is epileptic."

After the stroke in June 2001, Jacob, who will start Norristhorpe Junior & Infant School in September, was left paralysed down one side, unconscious and unable to speak for six days.

Doctors told Liz and Garry the stroke had knocked him back 12 months and had left him with only half a brain.

"He now has no concentration and his behaviour is worse than it was," said Liz, who admitted she had come close to breaking down. Everybody is just living on a knife-edge waiting for something to happen. Every morning I wake up and thank God he is still here."