Doctors Discover Happy Giggling Baby Was Having Laughing Seizures Caused by Brain Tumor

A stock image of a baby. Jack Young's parents became worried when his laughing became "relentless." Getty Images

When baby Jack laughed for hours a day, his parents just thought he was happy at first. But they later discovered a rare brain tumor was causing his unusual behavior.

Jack Young, from the county of Somerset, southeast England, U.K., started laughing when he was around two-weeks-old, PA Real Life reported. That's weeks before the 4 month milestone when most children start to laugh.

His mother, 32-year-old Gemma Young, told PA Real Life the family thought he was "so happy all the time."

But Jack's parents became worried when the sound became "relentless and so unpredictable," Young said. The giggling got so bad Jack slept downstairs to prevent him from keeping his brother awake in their room.

"I was terrified that it might never stop," Young said.

After the family endured the mysterious noise for six months, tests revealed his behavior was caused by a grape-sized brain tumor called a hypothalamic hamartoma.

Depending on which area of the brain the tumor impacts, those with the condition may at first experience a sensation of "rising" in their stomach, and numbness or tingling. Odd tastes and smells can hit, too, as well as a "hard to describe feeling," according to the Cleveland Clinic.

As the tumor develops, it causes gelastic epilepsy which can trigger uncontrollable laughing fits. Young said "the chuckle sound was constant," and the family had "no break from it."

The tumor itself is benign, but can lead to delays in development, behavioral issues as well as hormone disorders. If left untreated, it can prompt premature puberty, and in some cases death, according to UCLA.

After two years, Jack had an operation to remove the tumor - and the noise finally stopped.

"We were exhausted and so happy," said Young. "When we did hear him laugh properly for the first time it was amazing."

Last year, doctors at UCLA dealt with a similar case in Justin Cho.

Recalling a similar experience to Jack's parents, Robert Cho—the boy's father—commented at the time: "Justin has always been a happy child — very energetic and bubbly. We assumed that giggling was just part of his personality."

Surgeons at the institution were able to remove Justin's tumor in a minimally invasive procedure.

"It's a miracle," Cho said. "We're so grateful we learned in time that Justin had this issue and that we found doctors who were able to treat it the way they did."