See below... I am not an ENT doc, so I won't claim in knowing much about this beside little experience from my own patients etc...Here is a link for pretty good/accurate info (posted on aetna website) with lots of references behind it: http://www. Aetna. Com/cpb/medical/data/400_499/0403.Html so, if you are interested in learning about it...It is an good and acurate start. Good luck..