Brave little Sophie Fuller has been permanently brain damaged and has limited use of her right arm after suffering the stroke - which medics described as “extremely rare”.
Only five out of every 100,000 youngsters each year has a stroke in the UK - although research has shown chickenpox can increase the risk of ischaemic strokes in children.
It is thought the virus behind chickenpox causes blood vessels in the head to narrow, according to the Stroke Association.
Sophie takes blood thinning injections twice a day and the blood vessels are still very narrow since the stroke in July.
Although Sophie needs 24-hour care, she has now managed to returned to nursery for 45 minutes every day.
And she even has an adapted tricycle as she is unable to use her treasured bike, which was a birthday gift in April - the same month she had chickenpox.
Sophie has limited use of her right arm - which she terms her “rubbish arm”, and there is a risk of a stroke occurring again throughout her lifetime.
Mum Tracy, 33, said: “Sophie will always be at risk. It’s affected her mentally and physically.
“We keep her in our bedroom and don’t let her sleep on her own - we’re petrified.
“But we’ve had so much support. This is going to be a long journey.
“This has completely changed our lives.
“You’re living every single day and you’re reminded what happened.”
When Sophie became ill and fell out of bed on July 8, her dad Edwin immediately realised how serious the situation was.
Sophie was having a seizure in his arms, and Edwin, 32, and Tracy were worried as they waited for the ambulance to arrive at their home in Clydebank, West Dunbartonshire.
She was rushed to the Royal Hospital for Children, where she was cared for eight weeks.
Mum-of-three Tracy added: “When I saw her I panicked and said ‘she’s having a stroke’ - it’s absolutely heartbreaking.
“We are living in fear, making sure she is breathing, but we are a really strong family and have a lot of support.
“We witnessed everything she went through.
“They told us to keep talking to her.
“All I wanted to know was whether she was going to be alright.
“But nobody could tell me.
“My husband realised how severe it was. It’s just the worst thing you can possibly imagine.”
Doting siblings Courtney, 15, and Connor, 17, have rallied round to support their little sister in her recovery.
Tracy said: “The strength she has shown, we have got to keep going for Sophie - she needs us to keep going.
“Every single day we get upset but we have to hide that from Sophie.
“One of the physios said it’s almost like a grieving process.
“It’s almost like you have lost your wee girl.
“She was a very head-strong girl. She still is.”
Medics described the chances of such a young child suffering a stroke as “very, very rare”, Sophie’s mum said.
Tracy said: “No four-year-old should be experiencing this.
“Anyone can take a stroke at any age - I have learned so much.
“She’s come so far in only four and a half months.
“We are so proud of the journey she’s been through, and we want to thank everyone who supported us.
“The hospital staff saved her life. We can’t thank them enough.
“We feel they are part of our family because of what they have done.”
The family are looking forward to taking Sophie to Disneyland Paris next month so Sophie can meet her favourite character, Beast, from Beauty and the Beast.