Blog by Mel Barham
Imagine watching your precious child wheeled in to have ground-breaking surgery that's only ever been done in that hospital seven times before.
That's exactly what the family of Hallie Campbell are about to do.
The 6-year-old from Wigan is due to undergo pioneering experimental brain surgery in Poland after her family raised £70,000 for the opportunity.
Granada Reports correspondent Mel Barham and cameraman Jahmal Williams-Thomas have been given exclusive access to film her surgery and follow her journey as she travels more than a thousand miles from her home in Wigan to Poland's capital Warsaw, for treatment her family hope will transform her life.
Hallie is one of only 5 children in the UK - and the only girl - with an ultra rare condition called AADC deficiency.
It's a bit like Parkinson's Disease and means she can't walk or talk, she can't sit up by herself and she suffers almost daily seizures.
The operation is called Gene Therapy. The idea is that surgeons implant a non-mutated gene into Hallie's brain using a virus that's been made safe. That gene then spreads through her cells and starts to produce the enzyme AADC which currently doeasn't work in Hallie's body. That enzyme is needed to send signals to the brain between nerves.
But this procedure is so new that the surgeons are still learning and fine-tuning how to do it. It's currently only being trialled in America, but the Polish surgeon leading that research has decided to offer the treatment in Warsaw to children from the rest of the world on compassionate grounds. These children are all suffering from this condition called AADC deficiency which can be life-threatening and who wouldn't be entitled to take part in the trial in America.
Hallie is only the eighth child to undergo this surgery at the purpose-built theatre in Warsaw. For her family, this is a huge gamble - they are putting their trust in a medical team and a procedure where the results are far from clear.
When we arrived at the Brodnowski hospital on the outskirts of Warsaw the day before the operation, Hallie's family were both excited and anxious.
The enormity of this operation is not lost on the family. But they've watched their little girl suffering since she was diagnosed aged 6 months, and have been pining their hopes on this surgery ever since they found out about it.
After weeks of fundraising, the day of the operation is finally here. She's wheeled down the corridor in the special wing of the Brodno hospital, into the hands of the Polish medical team. It is an operation that's due to last anything up to 10 hours. All Hallie's family can do now is wait and hope.