Hi, James ~
Allow me to extend my own welcome to the site & the forum. I'm never pleased to learn of another AN diagnosis but I think you'll benefit from using the website and, especially, the discussion forums. To respond to your question: generally, acoustic neuromas tend to be very slow-growing, but they
can erupt in growth spurts, as happened to some of our members and, apparently, to you.
My large AN (diagnosed when I was a lad of 63) had, according to my neurosurgeon, probably been growing (at a glacial pace) for 10 to 15 years, which is fairly typical. Although the hearing ability in my left ear slowly but surely decreased, it was over a period of years and easily attributed to 'aging' and the fact that in my former profession (radio broadcaster) I wore tight-fitting earphones, often turned up to 'loud', many hours a day - for over 25 years. Approximately six months prior to my diagnosis, I became noticeably dizzy, lost my sense of taste (and 30+ pounds), felt intermittent stabbing pains on the left (AN) side of my head and became fatigued, which was out of the ordinary for me. I'm not athletic but I'm far from sedentary, even though I retired in 2005. I'm fortunate to not suffer from heart problems, back problems, diabetes, arthritis or male pattern baldness.
I assumed I would cruise into my dotage with no real physical problems, other than a slowing of body and mind as well as a few non-specific aches and pains. I was greatly mistaken.
In May, 2006, I consulted with my PCP about my ongoing symptoms. He first suspected 'a thyroid problem'. Unpleasant tests proved that my thyroid was working just fine. Next, he suspected a 'sinus problem'. That suspicion resulted in my enduring a 40-minute head-only MRI (with contrast) that 'discovered' my 4.5 cm acoustic neuroma, pressing hard on my vulnerable brainstem. A fruitless consult with a less-than-impressive local neurosurgeon, followed by a very encouraging 45-minute, uninterrupted consult with a neurosurgeon that had 30+ years of AN experience resulted in my hiring that fine doctor. He presented me with a detailed plan to, (a) surgically 'de-bulk' (reduce) the size of my AN (to approximately 2.5 cm) and, in the process, cut off it's blood supply, then, (b) to have me undergo 26 carefully 'mapped' (with the help of a radiation oncologist via CT and MRI scans) 26 FSR sessions intended to destroy the remaining tumor's DNA.
Long story short: the plan worked brilliantly. I emerged from the debulking surgery with no real complications. The radiation treatments were uneventful and my recovery from both procedures was swift and complete. Today, three years later, my AN experience is a memory and although I have a few very minor reminders of it; a very slight (left) 'dry eye', (blinking resolves that), a small 'numb spot' on the left side of my tongue and about 10% less sensitivity on the left (AN) side of my face. These are all unnoticeable to others and hardly noticeable to me. Frankly, I consider myself blessed by my surgery/radiation outcome but my experience is hardly unique, as other forum posters will attest from their own experience.
As you noted, these ANA forums are chock full of sensible, practicable information and a large group of caring people, eager to help other AN patients, especially those just diagnosed and feeling a bit adrift. You're part of a 'virtual' family here, James, and I hope you'll use the site and the forums as a resource as you find out more about your AN and decide how to deal with it.
Jim 
