Hi, Judy:
I commend you for doing your homework. That's arguably the most important factor in having a positive outcome from treatment.
Without knowing the dimensions of Bob's tumor, it's difficult to offer a completely valid perspective. But, FWIW:
HEI has a reputation for being a bit anti-radiation and pro-surgery, so I'm not surprised by what they told you. This is not to disparage HEI; they are an outstanding facility (perhaps the best, in terms of experience) for surgical resection of ANs. But since they don't offer CK and have no experience with it, it makes more sense to hear from the horse's mouth -- Dr. Chang, who is possibly the world's leading expert in CK -- an informed opinion about that form of treatment vis-a-vis your husband's AN. As Dr. Chang is a neurosurgeon, he will theoretically be unbiased when he tells you whether he thinks CK or resection is best for your husband.
Having said all that, I am quite puzzled that Dr. Friedman maintains that data suggests CK is not an effective treatment for ANs. I for one am living proof to the contrary, and you'll find many other people on this forum who have had outstanding results from CK.
If Dr. Chang recommends CK, Bob will still be left with the challenge of trusting his gut as to which doctor's lead to follow. But one way to clarify the situation is to ask each doctor for the odds, in percentage terms, of their recommended treatment causing Bob facial paralysis (and if it's likely to be permanent or temporary), hearing loss or deafness, chronic headaches, worsening dizziness or CSF leakage (the latter is only likely with surgical resection and is most likely to be a problem if Bob were to have translab-approach surgery). Once he knows the odds, he can choose which treatment he wants, with eyes wide open.
The reason why Bob is a candidate for retrosigmoid but not middle-fossa approach is likely because his AN is extending too far into the CPA (cerebellopontine angle) to effectively reach it via the latter approach. I do agree that a followup MRI only three months after the last one is unnecessary, as it would likely look exactly the same as the most current one taken. That's because ANs only grow on average 1 or 2 mm per year and MRIs have about a 2mm inherent error. You typically have to wait at least several months to see any change in an untreated tumor. The only reason to get one sooner than six months is if Bob's AN is approaching 3 cm in size -- the approximate cutoff for eligibility for radiation treatments -- and he wants to preserve that treatment option by not waiting until it exceeds that size. (It's a bit more complicated than that -- tumor volume is more of a determining factor than the dimension along any one axis, but 3 cm is an important number to watch.)
NF2 is highly unlikely in Bob's case. His doctors would have noticed any AN on the opposite side from his existing one, as MRIs scan the entire brain. Since they didn't see one on the opposing side, Bob can rest assured he does not have NF2.
A number of forumites have mentioned having brief stabbing pains on their AN side (myself included, although this was post-treatment) . It is pretty universally disregarded by doctors as having anything to do with ANs, but it is curious how many people have experienced this anyway.
I think once you talk with Dr. Chang, the picture will become clearer for you both. (He is my doctor, btw.)
Best wishes,
TW