Thirteen-year-old KatieRose Hamilton has the rare condition called trigeminal neuralgia, or TN.
"You know those thick kitchen knives? It feels like someone is stabbing that in the side of my head for like two to three hours and there's nothing you can do," said Hamilton.
Her mother, Megan Hamilton, says "it's horrifying" when the pain is going on.
"We can't even touch her. We can't talk to her. We have to be quiet. She lays there and she sobs," said Megan Hamilton.
The 13-year-old says the pain strikes with no warning and anything, such as cold air, can trigger it. She first experienced it at age 11.
"At first, I thought it was a headache, so I was thinking it would go away, but it didn't and it got worse," she said.
It took months to figure out what was wrong. The disorder, often associated with blood vessels or nerve clusters that compress the trigeminal nerve, triggers unbearable facial pain.
Officials say the disease affects about 1 in 15,000 people, striking mainly women over the age of 50. TN affects less than one percent of children.
Hamilton underwent brain surgery at Johns Hopkins University. Her mom says they thought they beat the disease. But eight months later, the pain returned and it was worse.
Hamilton manages the pain with medication. She and her family have traveled from their home in Virginia to the UC Irvine Medical Center in Orange, hoping Dr. Mark Linskey can help. Linskey has performed several operations on other children like Hamilton.
"We've been successful in every one so far, but that doesn't mean we'll be successful on everybody. The success rate for this operation is about 80 percent," said Linskey.
The 13-year-old says she is "kind of nervous" about the surgery.
"It's a major invasive brain surgery. It's a little scary and we'll wait until the end of the six or so hours when the doctor comes out to tell us what he found," said Megan Hamilton.
KatieRose Hamilton will undergo surgery on Tuesday. Her family is hopeful it will give her years without medication and years free of pain.
"Our goal is for surgery to keep her pain-free long enough to find a cure," said Megan Hamilton.