- Author: Itzhak Brook, MD, MSc; Chief Editor: John L Brusch, MD, FACP more...
Chronic sinusitis is one of the more prevalent chronic illnesses in the United States, affecting persons of all age groups (see Epidemiology). It is an inflammatory process that involves the paranasal sinuses and persists for 12 weeks or longer (see Pathophysiology). The literature has supported that chronic sinusitis is almost always accompanied by concurrent nasal airway inflammation and is often preceded by rhinitis symptoms; thus, the term chronic rhinosinusitis (CRS) has evolved to more accurately describe this condition.
CRS may manifest as one of three major clinical syndromes: CRS without nasal polyps, CRS with nasal polyps, or allergic fungal rhinosinusitis. These classifications possess a great deal of therapeutic significance.
Most cases of chronic sinusitis are continuations of unresolved acute sinusitis; however, chronic sinusitis usually manifests differently from acute sinusitis. Symptoms of chronic sinusitis include nasal stuffiness, postnasal drip, facial fullness, and malaise. (See Clinical Presentation.)
Chronic sinusitis may be noninfectious and related to allergy, cystic fibrosis, gastroesophageal reflux, or exposure to environmental pollutants.[1, 2] Allergic rhinitis, nonallergic rhinitis, anatomic obstruction in the ostiomeatal complex, and immunologic disorders are known risk factors for chronic sinusitis. (See Etiology.)
Medical therapy is directed toward controlling predisposing factors, treating concomitant infections, reducing edema of sinus tissues, and facilitating the drainage of sinus secretions. The goal in surgical treatment is to reestablish sinus ventilation and to correct mucosal opposition in order to restore the mucociliary clearance system. Surgery strives to restore the functional integrity of the inflamed mucosal lining. (See Treatment and Management and Medication.)
Definition of chronic rhinosinusitis
In 1996, the American Academy of Otolaryngology-Head & Neck Surgery multidisciplinary Rhinosinusitis Task Force (RTF) defined adult rhinosinusitis diagnostic criteria. Major factors included facial pain or pressure, nasal obstruction or blockage, nasal discharge or purulence or discolored postnasal discharge, hyposmia or anosmia, purulence in nasal cavity, and fever. In 2003, the RTF’s definition was amended to require confirmatory radiographic or nasal endoscopic or physical examination findings in addition to suggestive history.[4, 5] (See Clinical Presentation.)
Knowledge of the anatomy of paranasal sinuses is essential for understanding the pathophysiology and management of chronic sinusitis. The 4 pairs of paranasal sinuses are lined with ciliated, pseudostratified columnar epithelium. Goblet cells are interspersed among the columnar cells. The mucosa is attached directly to the bone. Involvement of the surrounding bone and further extension of the infection into the orbital and intracranial compartments can result from inadequate treatment of sinusitis and specific types of sinusitis (eg, fungal sinusitis).
The maxillary, frontal, and anterior ethmoid sinuses drain through their ostia located at the ostiomeatal complex lying lateral to the middle turbinate within the middle meatus. The posterior ethmoid and sphenoid sinuses open into the superior meatus and sphenoethmoid recess, respectively. The maxillary ostium is connected to the nasal cavity by a narrow tubular passage called the infundibulum, located at the highest part of the sinus; hence, drainage from the maxillary sinus flows against gravity via mucociliary clearance. Because the floor of the maxillary sinus is the tooth-bearing part of the maxilla, dental infections can easily extend to the maxillary sinus. Although the nasal cavity is usually colonized with bacteria, the sinuses are typically sterile.
Stasis of secretions inside the sinuses can be triggered by (1) mechanical obstruction at the ostiomeatal complex due to anatomic factors or (2) mucosal edema caused by various etiologies (eg, acute viral or allergic rhinitis).
Mucous stagnation in the sinus forms a rich medium for the growth of various pathogens. The early stage of sinusitis is often a viral infection that generally lasts up to 10 days and that completely resolves in 99% of cases. However, a small number of patients may develop a secondary acute bacterial infection that is generally caused by aerobic bacteria (ie, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis). Initially, the resulting acute sinusitis involves only one type of aerobic bacteria. With persistence of the infection, mixed flora, anaerobic organisms, and, occasionally, fungus contributes to the pathogenesis, with anaerobic bacteria of oral flora origin often eventually predominating. In one study, these bacterial changes were demonstrated with repeated endoscopic aspiration in patients with maxillary sinusitis. Most cases of chronic sinusitis are due to acute sinusitis that either is untreated or does not respond to treatment.
The role of bacteria in the pathogenesis of chronic sinusitis is currently being reassessed. Repeated and persistent sinus infections can develop in persons with severe acquired or congenital immunodeficiency states or cystic fibrosis.
Current thinking supports the concept that chronic rhinosinusitis (CRS) is predominantly a multifactorial inflammatory disease. Confounding factors that may contribute to inflammation include the following:
Persistent infection (including biofilms and osteitis) 
Allergy and other immunologic disorders
Intrinsic factors of the upper airway
Colonizing fungi that induce and sustain eosinophilic inflammation
Metabolic abnormalities such as aspirin sensitivity
All of these factors can play a role in disruption of the intrinsic mucociliary transport system. This is because an alteration in sinus ostia patency, ciliary function, or the quality of secretions leads to stagnation of secretions, decreased pH levels, and lowered oxygen tension within the sinus. These changes create a favorable environment for bacterial growth that, in turn, further contributes to increased mucosal inflammation.
Currently, etiologic studies of sinusitis are increasingly focusing on ostiomeatal obstruction, allergies, polyps, occult and subtle immunodeficiency states, and dental diseases. Microorganisms are more often recognized as secondary invaders. Any disease process or toxin that affects cilia has a negative effect on CRS.
The bacteria presumed to be involved in CRS differ from those involved in acute rhinosinusitis. The following bacteria have been reported in samples obtained through endoscopy or sinus puncture in patients with chronic sinusitis.
Staphylococcus aureus (both methicillin-susceptible S aureus [MSSA] and methicillin-resistant S aureus [MRSA] strains) 
In contrast with the well-established roles of microbes in the etiology of acute sinusitis, the exact roles of all of these microbes in the etiology of chronic sinusitis are uncertain. Various researchers disagree on the microbial etiology of chronic sinusitis. Much of the disagreement may be explained by methodology. Studies that have used adequate methods for recovery of anaerobes have demonstrated their prominence in chronic sinusitis, while those that did not use such methods have failed to recover them. When proper techniques are used, anaerobic bacteria can be recovered in 50-70% of specimens. The variable growth of microbes in samples may also be due to prior exposure of various broad-spectrum antibiotics in patients involved in the studies.
Jyonouchi et al successfully induced chronic sinusitis in rabbits via intrasinus inoculation of Bacteroides fragilis. The authors subsequently identified immunoglobulin G (IgG) antibodies against this organism in the infected animals. In addition, IgG antibodies to anaerobic organisms have been observed in patients with chronic sinusitis. These findings further support a role for anaerobes in chronic sinusitis.
Microbiologic studies of chronic sinusitis often show that the infection is polymicrobial, with isolation of 1-6 isolates per specimen.
In some cases, the baseline chronic sinusitis worsens suddenly or causes new symptoms. This acute exacerbation of chronic sinusitis is often polymicrobial as well, with anaerobic bacteria predominating. However, aerobic bacteria that are usually associated with acute sinusitis (eg, S pneumoniae, H influenzae,M catarrhalis) may emerge.
Gram-negative facultative and aerobic bacteria, including P aeruginosa, are more often isolated in patients with chronic sinusitis who have undergone endoscopic sinus surgery.
The following fungi have been reported in samples obtained with endoscopy or sinus puncture in patients with chronic sinusitis :
To see complete information on Fungal Sinusitis, please go to the main article by clicking here.
The following conditions and risk factors predispose patients to the development of chronic sinusitis:
Anatomic abnormalities of the ostiomeatal complex (eg, septal deviation, concha bullosa, deviation of uncinate process, Haller cells)
Nonallergic rhinitis (eg, vasomotor rhinitis, rhinitis medicamentosa, cocaine abuse)
Defects in mucociliary clearance
Hormonal (eg, puberty, pregnancy, oral contraception)
Obstruction by tumor
Immunologic disorders (eg, common variable immunodeficiency, immunoglobulin A [IgA] deficiency, IgG subclass deficiency, AIDS)
Primary ciliary dyskinesia, Kartagener syndrome
Repeated viral upper respiratory tract infections
Environmental irritants and pollutants
Gastroesophageal reflux disease (GERD). The reflux of gastric contents may play a contributing role in some cases of CRS; this relationship still needs to be better defined
Periodontitis/significant dental disease
Systemic diseases (ie, granulomatosis with polyangiitis (Wegener granulomatosis), Churg-Strauss vasculitis, sarcoidosis)
Yellow nail syndrome
Chronic sinusitis is one of the more prevalent chronic illnesses in the United States, affecting persons of all age groups. The overall prevalence of CRS in the United States is 146 per 1000 population. For unknown reasons, the incidence of this disease appears to be increasing yearly. This results in a conservative estimate of 18-22 million physician visits in the United States each year and a direct treatment cost of $3.4-5 billion annually. Chronic sinusitis is the fifth most common disease treated with antibiotics. Up to 64% of patients with AIDS develop chronic sinusitis.
Chronic sinusitis is a common disease worldwide, particularly in places with high levels of atmospheric pollution. In the Northern Hemisphere, damp temperate climates along with higher concentrations of pollens are associated with a higher prevalence of chronic sinusitis.
Rhinosinusitis in children
Rhinosinusitis is more common in the pediatric population because this term includes both acute and chronic infection and both viral and bacterial disease. This is likely secondary to an increased frequency of exposure to upper respiratory tract infections in the pediatric population.
Because of its persistent nature, chronic sinusitis can become a significant cause of morbidity. If left untreated, it can reduce the quality of life and the productivity of the affected person.
Early and aggressive medical treatment for chronic sinusitis typically results in satisfactory outcomes. Functional endoscopic sinus surgery (FESS) restores sinus health with complete or moderate relief of symptoms in 80-90% of patients with recurrent or medically unresponsive chronic sinusitis. (See Treatment and Management.)
Chronic sinusitis is rarely life threatening, although serious complications can occur because of the proximity to the orbit and cranial cavity. Approximately 75% of all orbital infections are directly related to sinusitis. Intracranial complications remain comparatively rare, with 3.7-10% of intracranial infections related to sinusitis. (See Complications.)
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