Hi, Scott:
Sorry for just seeing this thread now. I'm no expert when it comes to surgery for an AN; in the end, I chose radiation. But FWIW, here's my take on your situation:
As you probably know by now, an AN that is 3.5 cm is probably too big for radiation treatments. But you might contact Staten Island Hospital to get their prognosis. They do FSR (fractionated stereotactic radiation), sometimes on tumors over 3 cm in size. To my knowledge, they are the only medical center that sometimes performs radiation on operable ANs over 3 cm in size.
I would also contact House Ear Clinic for a free consultation. Dr. Derald E. Brackmann (his email is dbrackmann@hei.org) will review your MRI for free and give his opinion. He developed most of the techniques used in modern-day brain surgery and is an expert specializing in removing ANs. It couldn't hurt to see what he has to say.
Have you had an ABR (auditory brainstem response) test performed? It will tell your neurosurgeon what the chances of preserving your hearing will be. Basically, it measures the amplitude of response to stimuli at several points along the hearing nerve. In brief, a weak response means the nerve is almost shot and won't survive the trauma of surgery; a strong response means the hearing nerve is still in relatively good shape, and that might warrant a modified approach to try to save your hearing.
I would also ask your doctors if de-bulking the tumor, followed by radiation, might save your hearing and reduce the chance of damage to the function of your facial nerve. De-bulking removes enough of the tumor to allow irradiating its remaining tissue; by foregoing scraping every last bit of the tumor off your hearing and facial nerves, your chance of retaining more function from those nerves is increased.
While it's true that the retro-sigmoid approach poses a 10-15% risk of chronic headaches (thought to be due to bone dust from the operation being left behind inside the skull), to my knowledge this risk also exists (but posing a much smaller chance) with the translab approach. The main issue with translab, from my understanding, is that the facial nerve is really in the way of surgical instruments. That is, if you go through the IAC (internal auditory canal) to get to the main bulk of the tumor that lies in the CPA (cerebello-pontine angle), as with the translab approach, you've got roughly 1 cm of facial nerve to traverse along in order to get free and clear of it. If I'm not mistaken, there is a bigger chance of CSF (cerebrospinal fluid) leakage (out the nose) with the translab approach compared to retro-sigmoid, too.
In the end, you should trust the neurosurgeon you end up choosing for the best approach. You are wise to choose doctors who have the most experience in treating ANs. You know the saying, "This isn't brain surgery"? Well, this is brain surgery. You need experts with tons of experience on your team. It sounds like you're headed in the right direction.
Best wishes,
TW
