After NY State health officials said there are no known infectious or environmental causes for why numerous teen girls have Tourette's-like tics, victims and their parents appeared on the Today Show to express their frustration. Thera Sanchez, a high school cheerleader whose tics suddenly emerged last fall after taking a nap, said, "I’m very angry. I’m very frustrated. No one’s giving me answers." But one doctor who has treated some of the teens tells Today it's "conversion disorder"—a.k.a., mass hysteria.

The "mass hysteria" diagnosis was mentioned last week, with some experts saying that stress might have a basis in the symptoms, but parents are not convinced. They haven't been shown any data and Sanchez's mother, Beth Miller, wants the state to turn over information that's been collected "so I can proceed in finding a cure for our daughters." Watch the segment, which features Sanchez suffering some intense sudden movement:

Visit msnbc.com for breaking news, world news, and news about the economy

Today's psychologist Dr. Gail Saltz, who hasn't treated or examined any of the girls, said that when environmental and infectious factors are ruled out, and stress is cited, the diagnosis is usually "conversion disorder." She emphasized, "That’s not faking it. They’re real symptoms. They need a psychiatric or psychological treatment. Treatment does work." And neurologist Dr. Laszlo Mechtler, who has treated some of the girls, said, "It's happened before, all around the world, in different parts of the world. It's a rare phenomena. Physicians are intrigued by it. The bottom line is these teenagers will get better."