Have you reviewed your MRI results with the specialists at the GK Centre where you had your treatment? Is the neurosurgeon you met with fully experienced with GK treatment and it's results? There are many specialists out there, and some with substantially more experience than others regarding Gamma Knife. I would not jump into surgery without a second consult.
Prior to my GK treatment I met with neurosurgeons who knew about GK, but did not perform GK. I then found a neurosurgeon who excelled at both surgery and GK. He made it very clear to me that it could take 2 to 3 years before he would confirm if my GK treatment had been a success. He told me that swelling could come and go throughout that time frame as well as a host of symptoms and that everyone reacts differently to receiving radiation.
During the first 3 to 10 months post treatment I had a substantial amount of trouble with my balance, wonky head and ocular motor issues. I couldn't walk a straight line, I felt exhausted all the time and walking at night was terrible with lights and buildings bouncing all over the place! Grocery shopping was horrible, scanning shelves looking for specific products made me nauseous. Somewhere around the 10 - 12 month time frame I started noticing huge improvements. I am now 1 1/2 years post treatment and feel great. I feel like the worst is behind me now and I'm no longer having the issues I mention above.
I would strongly recommend a second consult prior to making any decisions. You may just have a tumor that is swelling aggressively and perhaps a round of steroids would help to settle things down. Worst case, the tumor is growing and surgery becomes your only option, but I would move forward at this point with caution and make sure you aren't jumping into a situation that is not necessary.
If surgery is required, make sure that your neurosurgeon has lots of experience removing AN's.
Best of luck and let us know how things go.