In November, before he was scheduled for major brain surgery, 10-month-old Evan was quiet and reserved. He suffered from severe infantile spasms, seizures that would happen several times a day, severely stunting his development.
So surgeons at Mattel Children's Hospital UCLA removed nearly all of the left side of his brain.
Now he makes eye contact and interacts with his brothers. Evan appears to be transformed.
"Evan has shown us things that we just really never thought was possible," said Evan's father, David Stauff.
A year ago, Evan was trapped in his head. The misfiring going on his brain caused seizures that continuously set him back. Medications didn't work. Doctors feared Evan would never learn to walk or talk. The only way to stop the seizures was to remove the left half of his brain.
"So far, they've been completely stopped, which is what we wanted," said Dr. Gary Mathern, a neurosurgeon at Ronald Reagan UCLA Medical Center.
He says when brain tissue is removed at such a young age, the other side will compensate.
"The other side is often able to take over for those functions, so while language typically is on the left side of 98-99 percent of us, at this young age, if that right side is in good shape, he will eventually learn to talk," said Mathern.
So what can you do with half a brain? Well, if you're right-brained like Evan, you're visual and creative. There's a whole world of possibilities for Evan, jobs like chefs, fashion designers and architects.
"I think Evan has a very bright future and can do anything he wants to," said David Stauff. "And we're going to support him and make sure that he can have those opportunities and be successful and lead a normal productive lifestyle."
Mathern says some of his patients who have had hemispherectomies have finished high school, and two have their driver's licenses.
"You'd be surprised at the spectrum of what people are able to do, especially if they do it early enough," he said.
He credits the Stauff family for acting quickly and giving Evan the best chance possible. Dr. Mathern says Evan will soon be able to sit up, crawl and eventually walk. He won't have peripheral vision on his right side, but he can see straight ahead and to his left just fine.