Well, I think you’ve done the worst one already! I believe you’ve had a craniotomy – which is like O.M.G. scary and can take a very long time to get better after. Stereotactic radiation therapy takes a few minutes to actually have the operation, depending on how long they need to zap you for. The head brace that they fit to make sure that the zaps all go in exactly the right place is very unpleasant but it’s a lot less to get over than a craniotomy.
The frame doesn’t pierce your skull. It is just fitted very tightly so it doesn’t shift. I would think you could talk to the doctor about your nervousness and claustrophobia and they might give you a drug to relax you.
@JD12 is a gamma knife patient: he can encourage you through what it is about. I really believe (as an operation) it is unpleasant rather than anything like as scary as a craniotomy.
The other thing to think about is that once it is done, every day thereafter you’d be getting a tiny bit better, so that a couple of years down the line, hopefully you can put having an aneurysm way behind you.
None of this is pleasant and none of us choose to be in this space but I really, honestly, think you’ve done the really difficult bit already. It’s put you off further surgery because it was so difficult but SRS (a.k.a. gamma knife) is not as scary. Honest.
Sending you my very best wishes!