Does an epileptic's brain work differently even when he's not having a seizure?

Complex question. There are many kinds of epilepsy. Some patients have seizures frequently without knowing (during sleep for example). Others actually have damaged areas in their brains (hippocampus) from repeated seizures. Also after seizure there is a post ictal period where they are very tired. Milder forms of epilepsy may have normal brain between seizures. They have a normal eeg - brain wave test.
NO. Alteration of brain function occurs only during seizure activity when abnormality is detected by eeg tracings depending on type of seizure.