But after having a classic epileptic seizure, doctors realized the spontaneous laughs were due to gelastic epilepsy.
A benign mass deep in the brain triggers them.
In the past, curing the problem meant open-brain surgery, and a long recovery.
Instead, the UCLA surgeons destroyed the mass through a 2-millimeter incision, and a tiny laser fiber, guided by GPS-like mapping.
"And we essentially cook it with thermal energy. So we're cooking this lesion from the inside out, and it cures the epilepsy," said neurosurgeon Dr. Aria Fallah.
Justin's father says his son hasn't had any laughing spells or seizures since what he calls the "miracle" surgery.
And he is back to his favorite activity - soccer.
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