First off, sorry to have you here
I wish you didn't need to be here but since your diagnosis you'll be so glad you found this place. A HUGE help in researching and getting opinions before making your decision. The fact you have great hearing with that size AN is testament to how random and different all our experiences with this stupid tumor present themselves.
A few questions if I may....with no hearing loss, how or what symptoms became present that facilitated your diagnosis? If diagnosed just a few weeks ago your AN size variance by various Dr. does seem a bit strange. I'd be asking them all why their measurements differ so widely. Some may measure differently I would guess, but when I was diagnosed all three doctors measurements were within 2mm of each other so I would be real curious as to what the cause of this was in your situation. Was one Dr. measuring widest point? Another total mass?
I would recommend sending your MRI CD to a few other Dr(s) for their input, even if not used I hear Dr. Chang at Stanford will give his opinion if your images are sent to him. With his experience it would be some nice input I would guess. In your situation I might also speak with doctors about dual attack, is there an option to excise a good portion and FSR the rest to save hearing? The makeup and position of your tumor may affect this, but some have gone this route.
If I remember correctly from my research before making my treatment decision retrosigmoid carried about a 10% risk for the headache issue post-op and can't remember exactly how long that lasted for the people who dealt with it.
Never forget it's your head and life your doctors are talking about, as some seem to forget it in their zeal to treat. Ask any question that comes up, write them down before going in for discussion so you don't forget. Doctors are just fellow humans like the rest of us, prone to treatment prejudices and biases like we all carry in life in certain areas or contexts. They can be wrong, they can make mistakes and they are not gods. Respect their opinions but don't bow to them imo.
I remember after meeting the first neurosurgeon (Dr. Samy at UC Neuroscience Inst) who said my tumor was too big for radiation, my wife was with me and was adamant about me getting it out. However, after researching more I decided to get other opinions about the radiation option. The second neurosurgeon (Dr. Warnick at Mayfield Clinic) said radiation was most definitely an option but he said it was up to me as he could see both options as valid. The third was a radiation Oncologist (Dr. Breneman at UC Neuroscience Inst) who obviously also said radiation was definitely an option. My wife was mad "why would the first guy say it wasn't an option when it was?". My answer was because he's human, he was a nice guy and obviously very good at his chosen craft, but still a human prone to bias. If I had just gone along like a sheep with no questions I'd of had surgery for sure as he cut off the other possibility. But, after coming here and reading up on AN and seeing all the other experiences with Dr's around the country I was better equipped to challenge them.
Bottom line, it's your head, your life and your family this tumor is messing with. Don't be afraid to challenge the system (doctors that is) if you feel like you're being herded in a certain direction. It could be because that's the best way, or it could be because that's all they know.
Good luck and God speed with your decision.
