Izaac Roberts has spent the last three years living with the devastating effects of his grade 2 brain tumour - enduring debilitating seizures, loss of speech and numbness down one side of his body.
At the beginning of this year, the 18-year-old became the youngest patient to ever brave an awake craniotomy at Royal Stoke Hospital, with the aim of ultimately curing his symptoms and saving his life.
But two hours into the high-risk brain surgery, Izaac suddenly suffered a seizure and neurosurgeon Mr Chan was left with a dilemma - continue operating and risk life-long complications or wait for it to pass?
Tonight, the fifth series of 999: Critical Condition airs on Channel 5 and follows the remarkable journey of Izaac - a teenager who beat all the odds and lived to tell the tale.
Ahead of the first episode, Izaac spoke to the Mirror about the extraordinary ordeal that changed his life forever. He said: "It was surreal. Mr Chang and his surgical team were absolutely amazing."
Izaac was 14 years old when he started experiencing seizures, and by the time he was 17, they'd ramped up to three times a day.
"I'd be unconscious for five minutes and the right half of my body would shake vigorously. I tried to get a GP appointment but they wouldn't see me," he explained.
"It went on and on and became more intense, so I took myself to A&E in September, where I was admitted to hospital for brain scans and tests."
Izaac, from Birmingham, always assumed that he had epilepsy and it came as a huge shock to be diagnosed with a severe brain tumour.
"I was referred to neurosurgeon Mr Chan who created a plan of action. He told me, 'I'm not going to bother with a biopsy. I'm just going to get it all out'," Izaac said.
"The psychiatrist gave me a really good idea of what brain surgery would be like. I was curious. My biggest concern was the long-term side effects and possibility of it spreading."
On January 5, Izaac was sent down to the operating theatre and Mr Chan drilled a hole in his skull while he was sedated, then woke him up once his brain was exposed.
While Mr Chan scraped the tumour from the surface of his brain, Izaac was wide awake and forced to read out key words from a list with a neuropsychiatrist.
It was vital for Mr Chan and his team to map out the 'dangerous' areas on the brain and avoid them. One millimetre the wrong way and Izaac's speech could've be compromised for life.
"I felt very alert. I remember the psychiatrist in front of me and the surgeons behind me. I couldn't relax, it was a very intense environment," Izaac said.
"It was very surreal. One moment I was doing the test and talking, and the next I could feel the right half of my body going. I couldn't speak."
Midway through the procedure, Izaac suddenly felt distressed and he began to have a seizure, while his brain was exposed and skull was open.
Mr Chan instantly reacted by flooding his brain with a saline solution, in a bid to shock his body. Izaac said: "It felt like having cold water chucked over me. Then we carried on."
After a seven-hour operation, Izaac thought it was all over. But an MRI scan the following day sadly revealed remnants of the tumour still there.
"About 10 days later, I got a phone call from Mr Chan who said there was a bit left. I was worried about chemotherapy or radiotherapy," Izaac said.
"But before I could even ask, he said, 'Come in on Monday and we'll do it again'. And we did."
The second surgery was even more tricky and lasted nearly 10 hours, as the rest of the tumour was stuck in a blood vessel.
"Mr Chan carefully took it all out. I was so shocked at how great his skills were. The tumour was benign and has completely gone," Izaac said.
"Six days after, I went back to University. Now I have no side effects and I live a completely normal."
Izaac is in his first year of his Computer Science degree at the University of Birmingham and is currently weaning himself off his seizure medication.
The fifth series of 999: Critical Condition starts tonight at 9pm on Channel 5.
