This article is from the Epilepsy FAQ, by Andrew Patrick (firstname.lastname@example.org) with numerous contributions by others.
Epilepsy is a chronic condition of recurrent unprovoked seizures.
Isolated seizures and provoked seizures (e.g., drug or alcohol induced)
are not Epilepsy even though the events are real seizures. There are
many types of non-epileptic seizures. Non-epileptic seizures differ
from epileptic seizures in that there is usually no evidence of
abnormal electrical activity in the brain after the seizure, and they
do not occur repeatedly. Some of the more common causes of
non-epileptic seizures are: low blood sugar, fainting, heart disease,
stroke, migraine headaches, kinked blood vessels, narcolepsy,
withdrawal, and extreme stress or anxiety.