Hi, Susan:
Well, that's a new one! If this happened to me I'm not sure if I would be amused or angry. An audiologist, with a PhD., no less, working in a hospital, demonstrating her total ignorance regarding treatment options for acoustic neuroma tumors....to a patient. Good thing you were informed and knew she was talking out of her...er, nose.
Write the letters. Be polite but clear that this audiologist with a PhD. is disseminating false and possible harmful information of a medical nature. She is grossly misinforming AN patients because she is misinformed, herself. Of course she should know better, but she obviously doesn't. Help her to get straightened out by her superiors, because anyone with a PhD working in a medical capacity is never going to accept correction from a mere (informed) patient. Only someone with a medical degree and the status to demand her attention can help this woman and correct her ridiculous misinformation that she merrily passes on, probably with an air of great authority, to patients already under stress and trying to sort through the shock of being diagnosed with an Acoustic Neuroma tumor in their head.
Bravo to you for at least trying to cut through her ignorance.
Jim