Epilepsy was a medical condition causing sudden, randomly occurring bouts of seizures and unconsciousness, lasting from minutes to hours. Severe cases caused violent convulsions in which the sufferer was at risk of injuring themselves.
It was one of a number of handicaps that randomly afflicted Grey Orions of any age, due to their genetic mutilation. Some affected Grey Orions, in stressful situations, could be also be driven into a convulsive rage in which they assaulted nearby persons or vandalized the environment. Afterwards, they fell into a deep sleep, and did not always remember their actions. (FASA RPG - The Orions module: Book of Deep Knowledge)