Para-nasal sinuses are four paired air-filled cavities surrounding the nasal passage. These cavities are formed by the bones of the skull and lined by a thin layer of tissues (epithelium), which resembles the lining of the nasal cavity. They connect with the nasal cavity through small openings. Sinuses produce mucus, which is normally drained out into the nasal cavity. Although the nasal passage contains bacteria, usually sinuses are sterile. When the sinus openings are obstructed or mucus drainage is impaired, the secretions can be retained in the sinuses, producing the typical signs and symptoms of sinusitis. Sinusitis refers to an inflammation of the sinuses. The retained secretions can be infected with viruses, bacteria, or fungi. Sinusitis is commonly associated with an upper respiratory tract infection and can occur with asthma.
Classification of sinusitis
By duration of illness,
When infectious, by the type of pathogen,
- Viral sinusitis
- Bacterial sinusitis
- Fungal sinusitis
(Photo courtesy: Daniel Oldfield)