Part of every child's life is birthday parties. Neurological normal kids have no problem with these events and they love attending.
Our lives, however, make it a little harder. There's knowing he's going to face overwhelming noises, have sensory overload from the sounds, more than likely at least one meltdown. Then we have to factor in that there will be limited routine and lots of chaos. While birthday parties are fun for most kids, for my little SPD, ASD, ADHD kiddo it can be exhausting.
I don't try to avoid parties, Nixon's only had 2 invitations this school year and we've attended (or made plans to attend) them both. But it takes a lot of preparation, both for Nixon and me. I start by reminding him it'll be loud. I then let him know that he will have to let the birthday child open his presents, without Nixon's help. I have to let him know that we may eat first or play first, there's no real routine.
The biggest thing I do for him is let him know that, at any time, he can ask me to leave or help him find a quiet corner. I also carry headphones in my purse, in case he just can't handle the noise. I try to make the car ride, to and from, as quiet as possible, allowing him to decompress immediately afterwards.
For me, I make sure I have a BIG cup of coffee. I also pack my balls-of-steel because I never know when I'll have to deal with an adult who doesn't understand Nixon's issues and tries to run his/her mouth. I've been lucky so far and never needed to use them, but with every event we go to, odds are eventually one day I'll need them.