This risky surgery is transforming the lives of some very sick Australian kids.

Three-year-old Gary Mulhall was having up to 200 seizures a day before undergoing a risky surgery that left him with only half a working brain.

The toddler was born with a severe, drug-resistant form of epilepsy, which resulted in the daily brain-damaging fits.

“If we didn’t do it he’d be a complete vegetable, never walk, never talk, not even recognise his mum and that’s if he even survived past the age of two. Without the surgery he wasn’t expected to,” his mother Kathryn Singleton told the Daily Telegraph.

“For us it wasn’t a choice, for a lot of the other families it’s a choice for a better quality of life but it was either do this or you will lose your son.”

Little Gary was on the front page news this morning:

The surgery, known as a hemispherectomy, involves the disconnection and removal of half a child’s brain, resulting in paralysis and loss of vision on the opposite side of the body.

Experts say, over time, the remaining section begins to compensate for the loss, due to a phenomenon known as ‘plasticity’.

“After surgery the child can function well but one thing that is certain after a hemispherectomy is that the child will have a profound weakness but in some children there can be improvement,” The Children’s Hospital at Westmead paediatric neurologist Dr Deepak Gill said.

He explained the younger the surgery is undertaken, the more functionality the child is likely to regain.

So far, Gary, who underwent the surgery at 3-months-old, is still unable to walk and has some vision problems in his left eye, but he’s improving every day.

Without the surgery his mother believes he wouldn’t have survived.

“It’s a drastic surgery to put your child through, doctors can’t guarantee what your child will be like afterwards,” Ms Singleton said, describing her son as a “very happy kid”.

“We are so lucky the surgery was available, most definitely, without it we wouldn’t have our smiling bright eyed boy,” she said.

“He’s still delayed but we believe he will catch up by the time he gets to school.

“He’s got half the processing space so he’s got work twice as hard as everyone around him but he’s a very happy determined little boy.”