Causes

• Polyps (small benign growths) in the nasal passage block mucus drainage and restrict airflow. Polyps themselves may be consequences of previous sinus infections that caused overgrowth of the nasal membrane.
• Enlarged adenoids can lead to sinusitis.

• Cleft palate
• Tumors
• Deviated septum (a common structural abnormality in which the septum, the center section of the nose, is shifted to one side, usually the left)

Click the icon to see an image of a deviated septum.

Bacterial Sinusitis

The bacteria most commonly implicated in sinusitis include:

• Streptococcus pneumoniae (also called pneumococcal pneumonia or pneumococci). This bacterium is found in between 20 - 43% of adults and children with sinusitis.
• H. influenzae (a common bacterium associated with many upper respiratory infections). This bacterium colonizes nearly half of all children by age 2, and causes about 25% of sinusitis cases in this group. Studies have reported the presence of this bacterium in 22 - 35% of adult sinusitis patients.
• Moraxella catarrhalis. Over 75% of all children harbor this bacterium, which causes about 25% of sinusitis cases.

Other possible bacterial culprits include:

• Other streptococcal strains
• Staphylococcus aureus

Fungal Sinusitis

While fungi are an uncommon cause of sinusitis, the incidence of such infections is increasing. At least 5 - 10% of chronic rhinosinusitis patients actually have a form of allergic fungal sinusitis. Some scientists believe that chronic sinusitis may be an immune disorder, rather than an infectious disease. Breakthrough research released in 2004 supports this theory. Researchers from the U.S. National Institute of Allergy and Infectious Diseases exposed immune cells from patients with chronic sinusitis and healthy volunteers to four common types of fungi: Alternaria, Aspergillus, Penicillium, and Cladosporium. Among the study’s findings:

• Cells from the sinusitis patients released inflammation-inducing proteins called cytokines including interferon-gamma, interleukin-5 (IL-5), and interleukin-13 (IL-13).
• Cells from healthy patients released very little interferon-gamma and no IL-5 or IL-13.
• The Alternaria fungus caused the most extreme immune response.
• The researchers also compared nasal secretions from the two groups and found no difference in fungi levels.
• These findings suggest that some people who suffer from chronic sinusitis have an extreme immune and inflammatory response to fungi and may benefit from anti-fungal treatment.