I dont know about the Gamma knife but I have had three treatments by Canadian surgeons using Percutaneous Rhizotomy on my Trigeminal. I had attacks daily and was poorly controlled by drugs including Gabapentin. Results were, first treatment 1.5 years of complete remission. No 2 failed but third has resuled in almost 3 years ofremission and going strong. Yes the facial numbness is there but a lot more livable with than the origional pain.
I am surprised that Rhizotomy is not mentioned more often in this forum.