While NY State health officials have found no cause for why numerous upstate teens have developed spasms and Tourette's-like tics, many of the girls and their parents insist there must be a reason for the sudden epidemic. Doctors believe it's "mass hysteria," because environmental and infectious factors have been ruled out for the LeRoy, NY teens, but now crusading activist Erin Brockovich is stepping in.

Brockovich, the single mom who attributed cases of cancer to Pacific Energy & Gas's toxic dumping in California and was portrayed by Julia Roberts, told USA Today that "after families of affected teens and other community members asked her to look into the Le Roy case, she has spent the past week studying federal and state reports of a 1970 train derailment that spilled cyanide and an industrial solvent called trichloroethene within 3 miles of the high school attended by the 12 girls who started reporting neurological symptoms last fall. Three other teens, including one boy, are reportedly experiencing similar symptoms."

She said, "When I read reports like this that the New York Department of Health and state agencies were well-aware of the spill and you don't do water testing or vapor extraction tests, you don't have an all-clear."

The State Department of Health has ruled out "Pandas -- a neurological disorder linked to streptococcal infections -- and the Guardasil HPV vaccine, which many of the girls did not receive," but one victim's father said of the "mass hysteria" (or "conversion disorder") diagnosis, "We don't really agree with it. Down the road, who knows. But for them to give that diagnosis, they have to rule everything else out. And they haven't done that."

There are also active natural gas wells near the LeRoy high school; the Sierra Club told the Democrat and Chronicle, "We believe that it would be premature to draw any correlation between these tragic and unexplained illnesses and the gas wells on the school's playing fields. But we have seen no evidence that these wells were adequately considered by the Department of Health as potential contributing factors to the illnesses in the initial investigation."

The National Institutes of Health tells ABC News that its Medical Neurology Branch has offered its help, "but have not been asked for yet... One of the difficulties in this is that there hasn't been a lot of attention to this problem or very much research into it, which has made it somewhat of a mysterious disorder." And here's the NIH's description of mass hysteria/conversion disorder:

Conversion disorder is a condition in which a person has blindness, paralysis, or other nervous system (neurologic) symptoms that cannot be explained by medical evaluation.

Causes, incidence, and risk factors:

Conversion disorder symptoms may occur because of a psychological conflict.

Symptoms usually begin suddenly after a stressful experience. People are more at risk for a conversion disorder if they also have a medical illness, dissociative disorder, or a personality disorder.

It is important to understand that patients are not making up their symptoms (malingering). Some doctors falsely believe that conversion disorder is not a real condition, and may tell patients the problem is all in their head. However, these conditions are real. They cause distress and cannot be turned on and off at will.

The physical symptoms are thought to be an attempt to resolve the conflict the person feels inside. For example, a woman who believes it is not acceptable to have violent feelings may suddenly feel numbness in her arms after becoming so angry that she wanted to hit someone. Instead of allowing herself to have violent thoughts about hitting someone, she may experience the physical symptom of numbness in her arms.