The dangerous and delicate surgery was carried out just three months ago - and now Cameron is already well enough to go to school.
The drastic treatment was needed because a rare bug was eating away at the right-hand side of her brain.
Parents Shelly and Casey can't believe her miraculous recovery either.
At the age of three, Cameron developed the devastating brain disorder Rasmussen's Encephalitis. This one-in-a-million disease ate away at the right side of her brain, triggering violent and unpredictable epileptic fits.
"She'd just be standing talking to you," said dad Casey, a 35-year-old financial adviser. "Then before you could blink an eye she would fall on the floor in a seizure."
Cameron was plagued by up to 15 fits every day that began just half-an-hour after she woke up.
Shelly, 34, said: "We would get her feeling good for just 20 to 30 minutes each morning. We were aware how precious that time was and how we had to enjoy it. Then she would collapse with her first seizure and they just continued." Cameron fell over so often that her parents decided the best way to protect her was to put her in a bike helmet all day long.
Doctors told the couple that, left untreated, Cameron's condition would only get worse. Seizures would be more frequent, she would gradually lose her mental faculties and could become paralysed. A high-risk operation - known as a hemispherectomy - to remove the entire right side of her brain was their last hope.
"In the beginning I was willing to do whatever it took to not have them take anything out of my child's head," said Casey. "But eventually we had to accept that it was our only option."
The painstaking surgery took eight hours and involved drilling into and removing a large piece of skull before the affected parts of the brain were removed bit by bit.
The effect of the surgery is like having a major stroke. With the removal of the right side of her brain, Cameron was unable to move her left side - one side of the brain controls the opposite side of the body. The right side also controls imagination and creativity while the left stores facts and reacts logically-as the graphic at the top of the page shows.
But intensive physical therapy helped get her back on her feet, and Cameron has started school as a typically chatty little girl. The only signs of her trauma are a slight limp and a scar underneath her hair.
"I feel as though our little girl is back," said Shelly, a former bank manager who is now a stay-at-home mum.
"Cameron always loved to sing and dance and perform, but as her seizures got worse she stopped doing that. It was like losing a child. To have her back talking and chatting and carrying on is what we wanted more than anything."
Dr George Gallo, one of the surgical team at the John Hopkins Medical Institute in Baltimore, US, is constantly surprised by children's quick recovery after such ops.
He said: "I always think that these children will wake up not talking, not moving and dependent on their parents for the rest of their lives.
"But that is not true. If they were sitting next to you, you would not be able to tell that they had had half their brain removed. At Cameron's age the brain has a remarkable capacity to reorganise itself, and one side of the brain can effectively take over the functions of the other damaged or removed side."
Shelly said: "Her quality of life is now 100 times better. I know she can't use the left side of her body as well but there is no way I would trade this for what she was like before. We've got our little girl back and that's wonderful."
Cameron's story is told in Extraordinary People: Living With Half a Brain on Channel Five at 9pm on October 1.
We're just so grateful that we've got our lovely little girl back
HOW THE BRAIN WORKS
Left half of the brain controls the right side of the body
It is seen as the practical side
It gives logic and common sense
It also stores facts and analyses what we see
Right half controls the left side of our body
It is seen as the creative part of the brain
It is where our imagination lies
It is also the part of us that encourages risk-taking