The role of allergy in chronic rhinosinusitis

Historically, sinusitis has been divided into three categories (acute, subacute, and chronic sinusitis) based on disease duration. Patients with chronic sinusitis have symptoms for more than 6 weeks. At the time this terminology was developed, all sinusitis cases were believed to be infectious, and this idea led to the prominent use of antibiotics and surgical drainage as treatment. It now is clear, however, that most patients with chronic sinusitis do not have an infectious disorder [1,2]. This finding has led to the need to develop more appropriate terminology to describe the myriad of conditions that make up chronic sinusitis. Four major pathophysiologic processes are responsible for chronic sinusitis. A small subset of patients has chronic infectious sinusitis. This subset typically involves patients with underlying humoral immune deficiencies, HIV infection, Kartagener syndrome, and cystic fibrosis. Most patientswith chronicsinusitis have an inflammatory disorder with prominent hyperplasia of immune cells. Chronic inflammatory sinusitis is believed to result from chronic or recurrent occlusion of the sinus ostia secondary to viral rhinitis, allergic rhinitis (AR), anatomic predisposition, or other causes. These processes lead to recurrent acute bacterial infections, possibly in association with barotrauma of the sinus cavities and damage to the respiratory epithelium, ciliary destruction, mucous gland and goblet cell hyperplasia, bacterial colonization, and ultimately chronic inflammatory changes. The inflammatory component of this form of sinusitis consists of a mononuclear cell infiltrate and may produce nasal polyps. Eosinophils are not a feature of chronic inflammatory sinusitis. When caused by anatomic occlusion, chronic inflammatory sinusitis is generally responsive to surgical interventions [3,4]. Because it is defined by the prominent expression of eosinophils and to distinguish it from chronic inflammatory sinusitis, the other idiopathic immune