Acute sinusitis often begins following a viral upper respiratory infection (common cold, viral rhinitis). The medical term sometimes used for acute sinusitis associated with a cold is rhinosinusitis. In fact, sinusitis without nasal symptoms is rare since the membrane of the nose and sinuses is contiguous. Viral infections can cause swelling of the mucous membranes surrounding the sinus drainage areas – especially the osteomeatal complex (passageway between sinuses and nasal cavity). Such infections impair mucociliary clearance of the sinuses.
Chronic allergies and gastroesophageal reflux can also cause swelling and reduced mucociliary clearance. Other factors can play a role in why you could develop sinus infections. For example, nasal passages and/or sinus openings vary in size. Smaller structures have less tolerance for swelling, creating an increased risk of sinus infections. A septal deviation from the center of the nose (a curvature of the bone and cartilage structure which separates the right and left nostrils) may obstruct airflow through the nostrils. This may also contribute to blockage of the sinus drainage sites.
These problems can affect the normal mucociliary clearance leading to increased risk of sinus infections from retention of secretions, bacteria and pollutants in the sinuses. The longer bacteria and viruses are retained in the sinus cavity, the greater the chance of sinus infection. An uncinate process is a bone protruding off the middle turbinate. An abnormally long uncinate process can block the outflow tract of the maxillary sinus.