Hi, Jo:
While there is no hard and fast number to gauge a surgeons expertise, obviously, more is better. I believe that a total of 100 AN removal surgeries should be the base number for considering a surgeon's expertise in the procedure, which is delicate, tedious and demanding of the surgeon. If a doctor performs 1 per month, that equates to 12 per year. That means that in eight years, a doctor will have performed 96 AN removal surgeries. Round that off to 100 and you have the base number (by my standards).
The first neurosurgeon I consulted grudgingly admitted to having performed 'maybe' 60 AN removal surgeries in his career (he was in his early 40's.) I passed. The neurosurgeon I hired was a man in his 60's with 30 years of AN removal experience and was very engaged with the latest methods. He is a member of the ANA and has been for years and years. My surgery and later radiation were successful. I always felt very confident in this neurosurgeon who was professional, respected (the hospital nurses raved about him), compassionate and very concerned about the patient's quality of life, post-op, not just 'getting the tumor out'.
I wouldn't presume to tell another AN patient what doctor to choose but I will advise you to have more than one consultation, politely ask serious, probing questions and don't be intimidated. You are the only one who will have to live with the results of the surgery. Be informed and pro-active.
I wish you all the best on this journey.
Jim