Verified answer

It is possible they were using an EEG to rule out causes of your symtoms of depersonalization/derealization - i.e. they could be caused by partial seizures/sub-threshold seizure activity, or they could be psychological. If they are cause by one, but they treat for the other, you wont get better.

Depersonalisation does not historically respond to drug treatment (although anxiety/depression that sometime underlies it can), although they're trying drugs now in trials they think may work. Other kinds of drugs can increase symptoms of depersonalisation, particularly illegal drugs (in fact, it's one of the reasons some people take them). So they may not be the best idea in your case.

However, you are allowed to go back to your doctor and sit down with him, and ask him exactly what these test results mean, what the next step it, and your prognosis (in fact, many nurses are of the very vocal opinion that doctors get paid so much more than them specifically so patients can do this - it's part of a doctors job). You have a right to know why they are running tests, what the results of the tests mean, and to have your diagnosis fully explained to you. If you think you may forget what you want to ask, write down a list of questions before your appointment to remind you.