I usually just leave a message and the doctor calls me back in the evening. If it's more than a quick question than I make a consult appointment.Maybe the office staff can give you the neuro's email address, it's the easiest way to reach my ds's neuro, I've even had replies over the weekend to questions. In general though you should be able to leave a msg for most specialists and they will call back. Most of our specialists usually call back at the end of the day when things quiet down.
I think they would put you through to the nurse at least, and she might relay the questions...we seem to work as much with the nurse as we do the neuro! But if you still don't feel comfortable with the nurse, just tell her that you would rather talk to the neuro directly, although, they might want to set up an appt for that.
edited: I should add that I have talked to the nurse, but then asked if she could have the neuro call me back and explain her answers etc...it seems to take a little longer when I want direct contact with the neuro, but she has still made time to talk on the phone at points.
I've always left a message asking for a return call. No problem.