febrile seizures

I have a friend who's younger brother and sister suffer from seizures. I know that this is not all that uncommon but the worrying part is that the brother is now 5 and he still has them and the sister only started getting them about 2 years ago, when she was 11. They have been to a doctor who said that although it is uncommon that the seizures continue at such a late stage children tend to stop having them as they grow older.
My question is when? The sister is now 13 and she had a seizure last night! Are there any environmental factors which may prompt a seizure(eg, people smoking in the house). What action should be taken as a precautionary measure? (EEG's, CAT-scan, etc)

your advice will be greatly appreciated

[Kevin Kennedy, Ph.D.]

Dear Andrew,

I'm going to defer on this question to my colleagues over on the Neurology Forum. This matter is more in their domain. Would you mind posting it to them?