 Introduction/Background Acute sinusitis is defined as an acute inflammatory process involving the paranasal sinuses. Acute sinusitis is common in children and usually resolves spontaneously, although it can result in serious complications [1-9]. Acute sinusitis may be viral, bacterial, or fungal. Viral upper respiratory tract infections occur with an incidence of six episodes per patient year, and 8% of these viral infections are complicated by acute viral sinusitis [2]. Inflammation of the mucosal lining of the nose and paranasal sinuses secondary to viral infection sets the stage for bacterial superinfection [10], thus making viral infections the most common predisposing factor for acute bacterial sinusitis, followed by allergic rhinitis [1,3-5]. Other noninfectious factors that may lead to sinusitis in children include nasal airway obstruction, immunodeficiency, ciliary dysfunction, cystic fibrosis, and odontogenic infections [1,3-9,11-13]. Imaging abnormalities alone are not sufficient for the diagnosis of acute sinusitis because paranasal sinus opacification is often present in healthy children or in children having a CT scan for other reasons. CT performed on young adults recovering from a cold illustrated that 87% had significant maxillary sinus abnormalities. One study showed that >50% of children with viral upper respiratory tract infection had abnormal maxillary sinus radiographs [2]. Further research showed that 68% of symptomatic children with upper respiratory tract infection and 42% of healthy children had significant sinus abnormalities on MRI [2]. This incidence is even higher in very young patient populations and reached 97% in a study of infants who had a cold in the 2 weeks preceding a head CT done for other reasons [15]. The AAP defines subacute bacterial sinusitis as a sinusitis that lasts between 30 and 90 days and whose symptoms resolve completely.
Sinusitis Child.  Introduction/Background Acute sinusitis is defined as an acute inflammatory process involving the paranasal sinuses. Acute sinusitis is common in children and usually resolves spontaneously, although it can result in serious complications [1-9]. Acute sinusitis may be viral, bacterial, or fungal. Viral upper respiratory tract infections occur with an incidence of six episodes per patient year, and 8% of these viral infections are complicated by acute viral sinusitis [2]. Inflammation of the mucosal lining of the nose and paranasal sinuses secondary to viral infection sets the stage for bacterial superinfection [10], thus making viral infections the most common predisposing factor for acute bacterial sinusitis, followed by allergic rhinitis [1,3-5]. Other noninfectious factors that may lead to sinusitis in children include nasal airway obstruction, immunodeficiency, ciliary dysfunction, cystic fibrosis, and odontogenic infections [1,3-9,11-13]. Imaging abnormalities alone are not sufficient for the diagnosis of acute sinusitis because paranasal sinus opacification is often present in healthy children or in children having a CT scan for other reasons. CT performed on young adults recovering from a cold illustrated that 87% had significant maxillary sinus abnormalities. One study showed that >50% of children with viral upper respiratory tract infection had abnormal maxillary sinus radiographs [2]. Further research showed that 68% of symptomatic children with upper respiratory tract infection and 42% of healthy children had significant sinus abnormalities on MRI [2]. This incidence is even higher in very young patient populations and reached 97% in a study of infants who had a cold in the 2 weeks preceding a head CT done for other reasons [15]. The AAP defines subacute bacterial sinusitis as a sinusitis that lasts between 30 and 90 days and whose symptoms resolve completely.