What is Sinusitis? Understanding Sinusitis Symptoms

What is Sinusitis? Understanding Sinuses and Infection

When patients ask “what is sinusitis” it is critical they understand the purpose and function of the sinuses. Our sinuses are air-filled spaces located in the bones of the face and skull that act as the body’s air filter. The thin layer of mucus they produce that normally flows freely into the nose is designed to moisten the air we breathe as well as trap and remove irritating, inhaled pollutants such as dust, mold, viruses and bacteria.

Normally, this mucus drains into the throat and stomach, taking with it the trapped pollutants and preventing potential infection. When the passages between the nose and sinuses become blocked, the mucus cannot drain properly. Instead, it becomes trapped in the nasal and sinus cavities, often leading to infection, a condition known as sinusitis.

This type of blockage can occur for various reasons. The most common cause is temporary swelling of the passages due to a cold or allergy. Congenitally narrow sinus outflow tracts (a condition some people are born with) can also contribute to repeated infection, as can a deviated septum, nasal polyps and other nasal abnormalities. Typically, multiple factors are responsible for sinus problems.

“When the passages between the nose and sinuses become blocked, the mucus cannot drain properly.”

Additional factors that reduce the mucous membranes’ ability to fight infection include:

  • exposure and sensitivity to mold
  • acid reflux (the reflux of stomach acid into the throat and nose)
  • allergies to pollen, dust, animals, and foods
  • poor air quality
  • immune problems
  • severe systemic disease