A 17-year-old Victorian schoolgirl is locked in a desperate struggle against a rare brain tumour that was only discovered after she had a fall during a netball game.

Ciara Nelson was playing a high-grade match with the Victorian Netball League development squad when she took a tumble and hit her head on the court.

Ciara’s mother Colleen Nelson said she initially thought her daughter had delayed concussion when, two days later, she started vomiting.

As a precaution, the teen’s GP referred her for a CT scan and then a MRI, which immediately raised a red flag, but for an unexpected reason.

“The radiologist came out to me and said, ‘if she vomits or if she’s got a headache take her straight to hospital’,” Ms Nelson told Nine.com.au

“I just turned around and said, “what the hell did you find?” And they said, ‘we found a lesion on her brain’.”

“By the next morning my GP had sent her straight to Monash medical centre’s emergency department with a letter to the neurosurgeon and by Monday she was operated on.”

Ciara with Dr Charlie Teo, her neurosurgeon.

The operation last May involved drilling a hole at the base of Ciara’s brain to allow a build up of fluid to drain out.

The tumour itself is on Ciara’s brain stem and has been classified as inoperable.

Doctors initially identified the tumour as a low-grade, indolent glioma, and predicted Ciara could live with for years or decades before it posed a problem.

But an MRI in November turned the family’s life upside down.

“We got the result in December and it basically told us that the tumour had turned malignant and that it was now a high-grade tumour,” Ms Nelson said.

Ms Nelson, a single mother with three daughters, has now found herself in the fight for Ciara’s life.

Ciara, with her younger sister Rylee.

“I’ve been told there’s a very high chance of Ciara going blind,” Ms Nelson said.

“The tumour is positioned near the optic nerve, so they believe that the first symptoms we will see is her eyesight.”

Ciara has so far remained largely unaffected by tumour, aside from some slight problems with her memory and concentration caused by the operation to drain the fluid on her brain.

“She is a walking medical mystery at the moment. Every time we’ve sent scans ahead and then they see her they look at her as if to say, ‘what the hell?’

“There is this perfectly normal teenage girl standing in front of them,” Ms Nelson said.

But locked in a race against time, Ms Nelson said she had sent Ciara’s scans to hospitals and universities around the world and “no-one would touch her”.

“My fight is to keep her that way. Why do I have wait until she is deficient before anyone will help?”

Unwilling to back down, Ms Nelson rallied all her strength and began waging a campaign to have her daughter seen by Sydney’s renowned neurosurgeon Dr Charlie Teo, who just recently agreed to take her on as a patient. “I would have sat on his motorbike every morning if I didn’t get an answer,” Ms Nelson said.

“I used every contact I had. I was very lucky in that I had people annoying him from all angles.”

“We knew Ciara’s tumour was rare, we knew where it was was where he specialises in. I knew at the end of the day that once he saw the pictures he would take her on. Because no one else can offer any help, no one.”

Dr Teo has said that he can remove Ciara’s tumour, but the risks are enormous and with the glioma appearing to change shape at every MRI, the surgeon has advised a wait-and-see approach.

At the first sign the tumour is growing, Dr Teo will operate.

The total cost of the surgery is likely to be about $150,000, but the family has already raised more than $80,000 through a GoFundMe page .