Chronic sinusitis, by definition, lasts longer than three months and can be caused by many different diseases that share chronic inflammation of the sinuses as a common symptom. Symptoms of chronic sinusitis may include any combination of the following: nasal congestion, facial pain, headache, night-time coughing, an increase in previously minor or controlled asthma symptoms, general malaise, thick green or yellow discharge, feeling of facial 'fullness' or 'tightness' that may worsen when bending over, dizziness, aching teeth, and/or halitosis.[citation needed] Each of these symptoms has multiple other possible causes, which should be considered and investigated as well. Unless complications occur, fever is not a feature of chronic sinusitis.[citation needed] Often chronic sinusitis can lead to anosmia, a reduced sense of smell.[citation needed] In a small number of cases, acute or chronic maxillary sinusitis is associated with a dental infection. Vertigo, lightheadedness, and blurred vision are not typical in chronic sinusitis and other causes should be investigated.
Chronic sinusitis cases are subdivided into cases with polyps and cases without polyps. When polyps are present, the condition is called chronic hyperplastic sinusitis; however, the causes are poorly understood[4] and may include allergy, environmental factors such as dust or pollution, bacterial infection, or fungus (either allergic, infective, or reactive). Non-allergic factors, such as vasomotor rhinitis, can also cause chronic sinus problems.[citation needed] Abnormally narrow sinus passages, such as having a deviated septum, can impede drainage from the sinus cavities and be a contributing factor.[citation needed]
Chronic rhinosinusitis represents a multifactorial inflammatory disorder, rather than simply a persistent bacterial infection.[4] The medical management of chronic rhinosinusitis is now focused upon controlling the inflammation that predisposes patients to obstruction, reducing the incidence of infections. However, all forms of chronic rhinosinusitis are associated with impaired sinus drainage and secondary bacterial infections. Most individuals require initial antibiotics to clear any infection and intermittently afterwards to treat acute exacerbations of chronic rhinosinusitis.
A combination of anaerobic and aerobic bacteria,[8][9] are detected in conjunction with chronic sinusitis. Also isolated are Staphylococcus aureus (including methicilin resistant S.aureus )[10] and coagulase-negative Staphylococci and Gram negative enteric organisms can be isolated. Typically antibiotic treatment provides only a temporary reduction in inflammation, although hyperresponsiveness of the immune system to bacteria has been proposed as a possible cause of sinusitis with polyps (chronic hyperplastic sinusitis).[citation needed]
Attempts have been made to provide a more consistent nomenclature for subtypes of chronic sinusitis. The presence of eosinophils in the mucous lining of the nose and paranasal sinuses has been demonstrated for many patients, and this has been termed Eosinophilic Mucin RhinoSinusitis (EMRS).[citation needed] Cases of EMRS may be related to an allergic response, but allergy is not often documented, resulting in further subcategorization into allergic and non-allergic EMRS.
A more recent, and still debated, development in chronic sinusitis is the role that fungus plays in this disease. Fungus can be found in the nasal cavities and sinuses of most patients with sinusitis, but can also be found in healthy people as well.[citation needed] It remains unclear if fungus is a definite factor in the development of chronic sinusitis and if it is, what the difference may be between those who develop the disease and those who remain symptom free. Trials of antifungal treatments have had mixed results.