DEFINITION AND CLINICAL FEATURES Acute rhinosinusitis (ARS) is defined as symptoms due to inflammation of the sinonasal cavities for less than a 4-week duration. Diagnostic criterion is defined as the presence of three cardinal symptoms lasting up to 4 weeks-purulent nasal discharge (Figure 8.1) plus nasal obstruction, facial pain-pressure-fullness, or both. In addition, ARS can be characterized by fever, cough, fatigue, hyposmia, dental pain, or ear fullness or pressure; however, these symptoms are less sensitive and specific. ARS can be divided into viral and bacterial. Viral ARS is more common and often preceded by an upper respiratory infection in which nasal contents are blown into the sinuses. Rhinovirus followed by influenza and parainfluenza viruses
was the most commonly aspirated virus from sinus puncture studies of patients with acute community-acquired rhinosinusitis. The most common bacterial isolates include Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Viral ARS is complicated by secondary bacterial ARS 0.5%–2% of the time. In order to truly distinguish between viral and bacterial ARS, one must obtain a culture; however, this is not practical given the incidence in the general population. Therefore, in order to distinguish between the two, one must rely on illness pattern and duration. Bacterial ARS is suspected if symptoms last more than 10 days, if there is worsening after an initial period of improvement, or if symptoms are severe with fevers >39°C/102°F, facial pain and purulent drainage that lasts for at least three consecutive days.