Acute and Chronic Bacterial Sinusitis
Itzhak Brook, MD, MSc
Department of Pediatrics and Medicine, Georgetown University School of Medicine, 4431 Albemarle St. NW, Washington, DC 20016, USA
Sinusitis is deﬁned as inﬂammation of the mucous membrane lining the paranasal sinuses. Sinusitis can be classiﬁed chronologically into ﬁve categories : Acutesinusitis: a new infection that may last up to 4 weeks and can be subdivided symptomatically into severe and nonsevere Recurrent acute sinusitis: four or more separate episodes of acute sinusitis that occur within 1 year Subacute sinusitis: an infection that lasts between 4 to 12 weeks, representing a transition between acute and chronic infection Chronic sinusitis: signs and symptoms that lastfor more than 12 weeks Acute exacerbation of chronic sinusitis: signs and symptoms of chronic sinusitis exacerbate but return to baseline after treatment In addition to chronicity of infection, sinusitis also can be categorized by mode of transmission and underlying conditions. These classiﬁcations include nosocomial sinusitis, sinusitis in severely immunocompromised hosts, and sinusitis ofodontogenic origin.
Anatomic considerations and pathogenesis The paranasal sinuses (maxillary, ethmoid, frontal, and sphenoid) comprise four symmetrical air-ﬁlled spaces lined by pseudostratiﬁed, ciliated, columnar epithelium. They are interconnected through small tubular openings, the sinus ostia, which drain into various regions of the nasal cavity (Fig. 1). The frontal, anterior ethmoid, andmaxillary sinuses open into the middle meatus, whereas the posterior ethmoid and sphenoid sinuses open into the superior meatus. The osteomeatal complex (OMC) is an important anatomic site that represents the conﬂuence of the drainage areas of the
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Fig. 1. Coronal view of the paranasal sinuses and the osteomeatal complex. (From Wald ER. Chronic sinusitis in children. J Pediatr 1995;127:341; with permission)
frontal, ethmoid, and maxillary sinuses (see Fig. 1). It is bound by the middle turbinate medially, the basal lamella posteriorly and superiorly, and the lamina papyracea laterally. It is open for drainage anteriorly andinferiorly. Blockage or inﬂammation at the OMC is responsible for the development of bacterial sinusitis, because the obstruction interferes with eﬀective mucociliary clearance . Because the mucous membranes lining the nasal chambers and the sinuses are continuous through the natural ostium and are histologically alike, any upper respiratory infection commonly results in an inﬂammatorysinusitis. Sinus infection, however, usually does not persist after the
ACUTE AND CHRONIC BACTERIAL SINUSITIS
nasal infection has subsided unless there is continued blockage at the OMC. At this stage, the sealed-oﬀ sinus fails to drain freely and is prone to secondary bacterial infection. The sinuses develop gradually throughout childhood and reach full development during adolescence. Becausethe infant is born with mainly the maxillary and ethmoid sinuses present, the frontal sinuses rarely become infected before 6 years of age. Occlusion of the sinus ostium is the major predisposing factor causing suppurative infection and most often is the result of a viral or other upper respiratory infection, a common event in early childhood. Other important contributory factors are congenitaland genetic factors  and acquired immune deﬁciencies [4,5]. Mechanical obstruction resulting in sinusitis can be related to various causative factors such as septal dislocation resulting from birth trauma, unilateral choanal atresia, foreign bodies placed in the nose, or fractures of the nose following trauma. Up to 30% of patients who have cystic ﬁbrosis may have polyps complicating the...