Discuss Lynn's answer to: What is Bilateral ethmoid sinusitus?

It is the infection and inflammation of the ethmoid sinus cavities that are located behind your nose and between your eyes.  When allergies flare sometimes the inflammation in your sinuses swell so much they clog the openings which drain out the fluid and become infected.  Sinusitis is a serious condition because there is so little material which separates the infection and your brain and if you get an infection in your brain, about the only way to treat it is to open your skull to treat it.  Better to control your allergy symptoms and exposure than resort to major surgery.