Sinusitis refers to inflammation of the paranasal sinuses. Per convention, the term sinusitis will be used interchangeably with rhinosinusitis throughout this chapter because rhinitis (inflammation of the mucosa of the nasal cavity) almost always accompanies sinusitis.
Sinusitis can be classified by the duration of illness. Sinusitis with a duration of less than 4 weeks is defined as acute,1,2 and sinusitis with continuous symptoms lasting for at least 90 days3 or 12 weeks2 is defined as chronic. Sinusitis lasting between 4 and 12 weeks has been termed subacute, but little evidence is available in pediatrics for defining sinusitis lasting between 4 and 12 weeks as a distinct clinical entity.4 The American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS) clinical practice guidelines for adult sinusitis recommends using clinical decision making to determine if patients with sinusitis lasting between 4 and 12 weeks more closely resemble acute or chronic sinusitis.2 Clinicians seeing children with sinusitis lasting between 4 and 12 weeks could reasonably do the same.
Sinusitis is the most common diagnosis that leads antibiotic prescriptions in outpatient settings in the United States for all ages, and the third most common reason (after acute otitis media and pharyngitis) that antibiotics are prescribed in outpatient settings to children.5,6 Sinusitis leads to an estimated 6.3 million visits to physicians’ offices and emergency departments per year in the United States for children, 85% of whom receive antibiotic prescriptions.5
Acute sinusitis is almost always preceded by a viral upper respiratory infection (URI). An estimated 5–10% of viral URIs among children are complicated by acute bacterial sinusitis, as defined by symptoms persisting for 10 or more days.4 Among 623 episodes of URI occurring in 112 children 6–35 months of age, 8% of URI episodes were complicated by sinusitis.7 Among 1307 children aged 1–5 years presenting to primary care pediatricians for any reason, 121 (9.3%) had either nasal congestion, discharge, or daytime cough lasting for 10 or more days without improvement (i.e., meeting diagnostic criteria for acute sinusitis), 40 of whom (3% of 1307) also had acute otitis media.8 If only children presenting for URI symptoms were considered, 17% of 502 met criteria for acute sinusitis based on 10 days of symptoms.8
Viral infections are the predominant cause of upper respiratory infections involving the nasal passages and sinuses. Common pathogens that cause viral rhinosinusitis include rhinovirus, coronavirus, respiratory syncytial virus, influenza, parainfluenza, and adenovirus.9,10
Evidence regarding the etiology of acute bacterial sinusitis in children is very limited. Only two small studies have been performed among children with acute sinusitis using maxillary sinus aspiration in the United States, both in the 1980s, prior to the introduction of pneumocococcal conjugate vaccine.11–13 In those ...