IMO, once you are sure you are going to have treatment, be it surgery or radiation, I would definitely look into your insurance and what it will cover. I don't know for sure about radiation, but I can tell you from experience that AN surgery is very costly. It involves time in the hospital (cost of OR, room & board), an anesthesiologist, one or two doctors who are specialists, nursing staff, meds from the hospital that are charged at an inflated price, etc. If my insurance wouldn't have covered my surgery, I would have been paying it off for a good number of years - provided the docs and hospital would have let me.
I never used a case manager myself, but my insurance is provided by my employer and I do know the broker who "sells" us the insurance. He is the one who negotiates our annual premiums, what our plan covers, etc. I've known him for numerous years, so when I ran into problems with the insurance company that I couldn't solve myself, I called him. He got the issues taken care of within a few hours.
I wish I had thought about a case manager because every time I called the insurance company - especially in the case of my BAHA coverage - I got a different rep and had to explain the entire situation to him/her. It seemed that even when the rep "pulled my file", there was no documentation in it of previous conversations I had had with other reps. I spent a lot of time repeating what it was I wanted to know, explaining what procedure I needed, and why I needed to have it. If your insurance is through your employer, and you don't have access to your broker, your HR person might be a good resource.
Also, you may want to check with your doctor to see if he has someone on his staff who can help you deal with your insurance company. I think most docs would be willing to personally help you with this, but they have so many other things they are doing that they tend to hand clerical tasks to their staffs. Even after my insurance company said they'd pay for my AN surgery they had questions post op and said there were certain things they wouldn't pay for without further explanation. Each time I called them to straighten things out, I found that my doc's office had already beaten me to the punch and solved the problem. They had handled everything before I had even received my copy of the correspondence from the insurance company.
I don't think mentioning your AN to your insurance company would be setting yourself up for a battle. They can't exactly question medical necessity if it's obvious that you have an AN. They may try to limit your coverage, but your policy should pretty much spell out what your plan does or does not cover. If they get difficult, you may need to be firm by persistent; don't take no for an answer. Ask to talk to supervisors if necessary; a lot of "claims" people just tell you what they are told to tell you - they have no real authority.
I've found in the past when dealing with my insurance company, that you sometimes need to question them or tell them you want your case reviewed by someone who understands what you are requesting. After my surgery, my insurance company questioned why I was in the hospital for 5, as opposed to 4, nights. I asked them who decided that 4 nights was "reasonable & customary". They told me that their independent reviewer had decided. When I asked them the qualifications of this reviewer, I was told it was an internist. When I pointed out that an internist who had never performed an AN surgery couldn't reasonably decide how much time I personally needed to recover, and insisted that they have my claim re-reviewed by a doc with qualifications comparable to my neurotologist and/or neurosurgeon, they changed their tune fairly fast.
Insurance companies like to hang onto their money as long as they can; lots of insureds unknowingly facilitiate this. Make sure you stand up for yourself and your rights.
Best of luck; you'll get through this,
Jan