Chronic Sinusitis

Updated: Jan 19, 2022
  • Author: Itzhak Brook, MD, MSc; Chief Editor: John L Brusch, MD, FACP  more...
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Practice Essentials

Chronic sinusitis is an inflammatory process involving the paranasal sinus and persisting for at least 12 weeks. Because nasal airway inflammation usually accompanies chronic sinusitis and rhinitis symptoms precede it, the term chronic rhinosinusitis (CRS) is a more accurate term. Chronic rhinosinusitis is one of the more common chronic diseases in the United States, and it affects those of all ages.

CRS may be noninfectious and associated with allergy, cystic fibrosis, gastroesophageal reflux, or exposure to environmental pollutants. Known risk factors include allergic rhinitis, nonallergic rhinitis, anatomic obstruction in the ostiomeatal complex, and immunologic disorders.

Individuals with CRS may have one of the following three major clinical syndromes:

  • CRS without nasal polyps
  • CRS with nasal polyps
  • Allergic fungal rhinosinusitis

Although most cases of CRS result from unresolved acute sinusitis, the two conditions have different manifestations. CRS often develops gradually over months or years, but it may begin suddently as an upper respiratory tract infection or acute sinusitis that fails to resolve.

Symptoms of CRS include the following:

  • Nasal obstruction, blockage, congestion, or stuffiness; nasal discharge (any); postnasal drip; sneezing

  • Facial fullness, discomfort, pain, and headache (more with nasal polyposis); stuffy ears

  • Sore throat, fetid breath, dental pain (upper teeth), unpleasant taste, hyposmia or anosmia, anorexia

  • Chronic unproductive cough (primarily in children)

  • Malaise, easy fatigability

  • Visual disturbances

  • Exacerbation of asthma

  • Unexplained fever

Diagnosis of chronic sinusitis

Serious underlying conditions, such as tumors and immunodeficiency states, should always be considered in the workup of chronic sinusitis. 

Radiologic examination is the cornerstone in the diagnostic workup of chronic sinusitis. Nasal endoscopy usually is recommended before obtaining imaging, because is shows the condition of the nasal mucosa and evaluates for purulent drainage.

Imaging studies

Plain radiographic views provide limited information regarding anterior ethmoid anatomy; computed tomography (CT) is often used for preoperative evaluation, and magnetic resonance imaging (MRI) is used to exclude orbital and intracranial extension.

Bacterial and fungal cultures

These are obtained directly from the sinus cavity (by maxillary sinus tap or during surgery) or endoscopically from the ostia. Nasal swab cultures have no diagnostic value.

Management of chronic sinusitis

Management of CRS may include medical and/or surgical treatment.

Medical treatment

Medical therapy is directed toward controlling predisposing factors, treating concomitant infections, reducing edema of sinus tissues, and facilitating the drainage of sinus secretions. Treatment often involves a combination of the following:

  • Topical or oral glucocorticoids
  • Antibiotics
  • Nasal saline irrigation

Refer the patient to an otoloaryngologist for surgical evaluation if the above measures fail.

Patients with orbital and intracranial complications, immunosuppressed patients, and pediatric patients may require inpatient treatment of CRS, depending on its severity.

Surgical treatment

Surgical treatment may be needed to reestablish sinus ventilation and to correct mucosal opposition to restore the mucociliary clearance system.  The goal of surgery is to restore the functional integrity of the inflamed mucosal lining. 



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. [3] 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 four 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 [6] contribute 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. [7] 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 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) [8, 9]
  • Allergies and other immunologic disorders [10]
  • Intrinsic factors of the upper airway
  • Superantigens
  • 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.



The etiology of chronic sinusitis is multifactorial. The interaction between many systemic, local host, and environmental factors contribute to sinus inflammation and to the pathophysiology of the disease. Systemic factors include genetic diseases such as cystic fibrosis, conditions that cause immunodeficiency, autoimmune disease, idiopathic conditions such as Samter triad (aspirin-exacerbated respiratory disease), and acid reflux. Local host factors include sinonasal anatomic abnormalities, iatrogenic conditions such as scarring due to prior sinus surgery, neoplasm, or the presence of a foreign body, among others. Possible environmental factors that may contribute to the condition include the presence of biofilms and bacterial infection, as well as fungal infection, allergy, environmental pollutants, and smoking.

Increasing evidence shows that biofilms are critical to the pathophysiology of chronic infections including chronic sinusitis. Recent advances in methods for biofilm identification and molecular biology offer new insights into the role of biofilms in chronic sinusitis. [11]

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.

Bacterial involvement

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) [12]
  • Coagulase-negative staphylococci
  • Haemphillus  influenzae
  • Moraxella catarrhalis
  • Streptococcus pneumoniae
  • Streptococcus intermedius
  • Pseudomonas aeruginosa
  • Nocardia species
  • Anaerobic bacteria ( Peptostreptococcus, Prevotella, Porphyromonas, Bacteroides, Fusobacterium species [13, 14]
  • Microaerophilic streptococci [15]

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, whereas those that did not use such methods have failed to recover them. When proper techniques are used, anaerobic bacteria can be recovered in 50% to 70% of specimens. [14] 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. [16] In addition, IgG antibodies to anaerobic organisms have been observed in patients with chronic sinusitis. [17] 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 one to six isolates per specimen. [13]  The microbial flora of chronic sinusitis is affected by previous antibiotic administration, past vaccinations, and the presence of normal flora that can suppress the emergence of pathogenic species.

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. [18]  A change of bacterial isolates during the course of recurrent exacerbation was observed in 68% (76/112) of patients studied by Yaniv et al, [19]  necessitating a change of treatment in 40% (45/112). The main risk factor for the subsequent change in cultures was polymicrobial growth. The authors recommended that repeated middle meatal cultures should be considered in patients with recurrent exacerbations of CRS, particularly in cases not responding to standard therapy.

S aureus including methicillin resistant [20]  is associated with the development of persistent severe inflammatory disease of the upper airway, including chronic sinusitis with nasal polyps. [21]

Gram-negative facultative and aerobic bacteria, including P aeruginosa, are more often isolated in patients with chronic sinusitis who have undergone endoscopic sinus surgery. [22]

Fungal involvement

The following fungi have been reported in samples obtained with endoscopy or sinus puncture in patients with chronic sinusitis [23] :

  • Aspergillus species

  • Cryptococcus neoformans

  • Candida species

  • Sporothrix schenckii

  • Alternaria species

Polymicrobial aerobic-anaerobic flora is sinus cultures obtained from present with fungus ball. [24]  To see complete information on fungal sinusitis, please go to the main article by clicking here.

Risk factors

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)
  • Allergic rhinitis [25]
  • Aspirin sensitivity
  • Asthma
  • Nasal polyps
  • Nonallergic rhinitis (eg, vasomotor rhinitis, rhinitis medicamentosa, cocaine abuse)
  • Defects in mucociliary clearance
  • Nasotracheal intubation
  • Nasogastric intubation
  • Hormonal (eg, puberty, pregnancy, oral contraception)
  • Obstruction by tumor
  • Immunologic disorders (eg, common variable immunodeficiency, immunoglobulin A [IgA] deficiency, IgG subclass deficiency, AIDS)
  • Cystic fibrosis
  • Primary ciliary dyskinesia, Kartagener syndrome
  • Repeated viral upper respiratory tract infections
  • Smoking
  • 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. [26] Chronic sinusitis is the fifth most common disease treated with antibiotics. Up to 64% of patients with AIDS develop chronic sinusitis. [27]

International prevalence

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.

Chronic sinusitis is associated with exacerbation of asthma and serious complications such as brain abscess and meningitis, which can produce significant morbidity and mortality.

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% to 90% of patients with recurrent or medically unresponsive chronic sinusitis.(See Treatment and Management.)

Chronic sinusitis rarely is 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% to 10% of intracranial infections related to sinusitis. [28] (See Complications.)