As an adult who suffered with chronic sinus infections and lived on antibiotics year round (as well as steroid nasal sprays, antihistimines, and decongestants) and still could not stay well more than 3 weeks at a time, I can say that my sinus surgery was a tremendous success.  I had Functional Endoscopic Sinus Surgery (FESS) twice.  The reason it had to be done twice is that I had a deviated septum that was discovered during the first surgery so I had to be put to sleep for the second one so they could fix that.  I have never had more than one sinus infection in a 12-18 month period since the surgery.  They removed part of the middle turbinate (nasal tissue) during my surgery.  Repeated sinus infections can cause damage to the sinuses - best get it fixed if needed.

Now, for my CAH daughter, she had tonsils and adenoids out at the same time.  We stress dosed for a day or two prior to surgery, she had the IV with the meds at the hospital and we stress dosed for a number of days after the surgery.  She did jut fine.

Good luck if you choose to go with surgery.  If you go for the surgery just get the endo and the ear, nose and throat doctor to consult and be prepared to give the proper meds during the procedure.

Kay