Story highlights "Conversion disorder" causes twitching, stuttering, verbal outbursts

Doctor says it is caused by "stressors that provoke a physical reaction"

Mayo Clinic says young females are much more likely to get conversion disorder

Twelve female students from Le Roy Junior Senior High School in upstate New York are experiencing a mysterious medical condition. Their symptoms include stuttering, uncontrollable twitching movements and verbal outbursts.

Health officials say the symptoms are consistent with "conversion disorder."

Dr. Jennifer McVige, a pediatric neurologist at the DENT Neurologic Institute who is treating many of the students affected, said, "Conversion disorder is a physical manifestation of physiological symptoms where there is traditionally some kind of stress or multiple stressors that provoke a physical reaction within the body." McVige said the symptoms are real. "This is unconscious. It is not done purposefully."

Thera Sanchez, a senior on the honor roll at the school, said she has been fighting this affliction since October. She said after waking up from a nap, "I got upset, I couldn't stop stuttering." During an interview with CNN's Jason Carroll, her symptoms were apparent: She was twitching uncontrollably, flailing her left arm and jerking her head to one side. Sanchez said she also faints and has seizures. The seizures are a result of her pre-existing epilepsy disorder, which had been under control for years.

Lydia Parker, also a senior at the school, is exhibiting similar symptoms. "I took a five-minute nap. I passed out for five minutes and I woke up stuttering," Parker said. She said her symptoms also started in October. Parker has a bruised forehead after banging it on her bedpost during a fainting spell, she said.

Officials at the school hired an independent third party to conduct mold and air quality tests but found no environmental cause for the girls' illnesses. A statement posted on the school's website said, in part, "The medical and environmental investigations have not uncovered any evidence that would link the neurological symptoms to anything in the environment or of an infectious nature."

Sanchez's mother, Melissa Phillips said she does not agree. "I don't think that all physical aspects of this have been exhausted; not enough testing has been done."

Phillips said she found out other girls were exhibiting the same symptoms when she brought her daughter to the hospital. The nurse said Thera was the fourth girl in a week to come in with the same issues. "I was very irate to not know that other girls were going through this."

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She also disagreed with McVige's assertion that the girls are improving, saying, "Nothing is getting better, you know, the girls are still getting worse. They have good days and bad days."

McVige is not sure why so many girls at the same school are suffering all at once. "I do know that traditionally when they've (doctors) looked back at different events that occurred in a similar nature, a majority of the time it is girls."

According to the Mayo Clinic, females are much more likely to get conversion disorder and it is more common in adolescents or young adults.

McVige said she used the "diagnosis of exclusion" to determine what happened to the girls, which means using the process of elimination. She ruled out a laundry list of factors to reach her diagnosis, including infections, drug use, food allergies and vaccine reactions, specifically Gardasil.

The New York State Health Department agreed with McVige's diagnosis after speaking with several doctors who evaluated the students. "There are many causes of tic-like symptoms. Stress can often worsen them," said spokesman Jeffrey Hammond. "The doctors all agree that the symptoms these girls are experiencing are real."

This isn't the first time reports have surfaced of multiple students at one high school experiencing twitching symptoms. In 2007, nine female students and one teacher were reported to have the same issues at William Byrd High School in Roanoke, Virginia. The school spent $30,000 testing the school and the surrounding area but found no evidence of any environmental factors that may have contributed to the illnesses.

The school principal, Richard Turner, said after closely interviewing the students, they found six of them were faking the symptoms. The teacher who was affected is now symptom free and still teaching at the school. One student who got better within days, according to Turner, was determined to have had a reaction to medication.

The other two students' symptoms were eventually resolved.

All of them graduated. "We haven't had any other reported incidents since then," Turner said.

The Virginia Department of Health also did an investigation and told CNN it found no contributing environmental factors and concluded the students' symptoms, though varied, were consistent with a social phenomenon called "mass psychogenic hysteria," which suggests real symptoms but no biological cause.

Thera Sanchez said all she wants is to get better so she can go to college next year. "I don't think this is in my head."

McVige said she wanted to assure the public that this illness will not spread. "I feel we need to put an end to feeling that this is a mystery, that someone is going to catch something contagious." She expressed confidence all the girls will get better, adding they have "an excellent prognosis."