About 2.5 million people in the United States have epilepsy, a term that covers a spectrum of neurological disorders characterized by recurring seizures.
The seizures range from so mild they are hardly detectable to grand mal episodes in which muscles forcefully contract and the body goes rigid.
Contrary to widespread belief, epilepsy is most often diagnosed in adulthood, with 70% of the 125,000 new cases each year involving people over 18, according to the Epilepsy Foundation of America.
The roots of the problem lie in disruptions of nerve function in the brain, and in most cases the reason is unknown. However, in 30% of cases a tumor, viral infection or other factor is identified as the trigger.