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Chronic rhinosinusitis (CRS) is a heterogeneous, predominantly inflammatory disorder of the nasal and paranasal sinus mucosa characterized by at least 12 weeks of symptoms and objective evidence of mucosal disease. Common manifestations include nasal obstruction, discolored anterior or posterior drainage, facial pressure, and reduced olfaction, while fever and significant pain may be absent. Diagnostic accuracy remains challenging because symptom burden may correlate poorly with endoscopic and radiographic findings, and there is clinical overlap with viral upper respiratory illness, rhinitis, migraine, dental disease, and recurrent acute rhinosinusitis. Long-term management frequently requires sustained topical therapy, trigger control, and escalation to surgery or biologics for selected phenotypes. Course participation builds competence in evidence-based evaluation and individualized management of CRS across phenotypes, including CRS with and without nasal polyps. Participants learn to obtain a focused history, perform targeted head and neck examination, interpret nasal endoscopy findings, and apply appropriate imaging strategies to confirm inflammation, define anatomy, and identify complications. Instruction emphasizes rational selection of therapies that improve drainage, enhance mucociliary clearance, reduce inflammation, and optimize topical medication delivery, while reinforcing stewardship principles that limit unnecessary antibiotics and systemic corticosteroids. Collaboration with an interprofessional team (including clinicians, nurses, pharmacists, allergy and pulmonary specialists, radiology, and ophthalmology) strengthens diagnostic precision, improves adherence to long-term plans, accelerates recognition of complications, and advances patient-centered outcomes such as symptom control, function, and quality of life. Objectives: Apply objective diagnostic criteria and guideline-concordant evaluation pathways to confirm chronic rhinosinusitis and document mucosal inflammation. Differentiate chronic rhinosinusitis from recurrent acute rhinosinusitis and common mimics (eg, viral upper respiratory tract infection, nonallergic rhinitis, migraine, dental disease, neoplasm, fungal disease) using history, examination, and objective findings.

Apply objective diagnostic criteria and guideline-concordant evaluation pathways to confirm chronic rhinosinusitis and document mucosal inflammation. Differentiate chronic rhinosinusitis from recurrent acute rhinosinusitis and common mimics (eg, viral upper respiratory tract infection, nonallergic rhinitis, migraine, dental disease, neoplasm, fungal disease) using history, examination, and objective findings. Select appropriate laboratory testing, culture strategies, and biopsy indications to evaluate immune dysfunction, allergy, fungal disease, and malignancy when clinically warranted. Improve collaboration and communication among the interprofessional healthcare team (eg, clinicians, nurses, pharmacists, allergy/immunology, pulmonology, radiology, ophthalmology) to coordinate care, recognize complications early, and optimize outcomes. Access free multiple choice questions on this topic.

Chronic rhinosinusitis (CRS) is characterized by persistent sinonasal symptoms with mucosal inflammation lasting 12 weeks or more. Diagnosing CRS can be more difficult than diagnosing acute sinusitis because common symptoms like fever and facial pain may be absent or mild. CRS can develop after an episode of acute sinusitis or a viral upper respiratory tract infection, but not all acute cases progress to CRS. CRS may develop gradually over months or years. Diagnostic uncertainty is common because symptom severity may not correlate with patient history, endoscopic findings, and radiographic imaging. The etiology of CRS may involve systemic factors: Genetic conditions Immunodeficiency Autoimmune diseases Idiopathic conditions Local factors also influence the etiology: Sinonasal anatomical abnormalities Obstruction Neoplasms Routine laboratory tests are often low-yield unless other comorbidities are present. Key diagnostic methods include contrast-enhanced computed tomography scans with thin-cut coronal slices, nasal endoscopy (possibly with culture or biopsy), and MRI (typically reserved for complex cases involving intracranial, ocular, or fungal complications). Treatment begins by managing predisposing factors such as viral upper respiratory tract infections, environmental or allergic triggers, asthma, immunodeficiency, gastroesophageal reflux disease, or, rarely, cystic fibrosis. Pharmacologic treatment may include symptomatic therapy, corticosteroids, antimicrobials, or other targeted agents. In those with severe or refractory disease, the recently approved humanized monoclonal antibody dupilumab may be considered.[1] Surgical treatment options include open approach sinus surgery, functional endoscopic sinus surgery, and balloon sinuplasty for certain cases. Potential complications include superimposed infections, orbital involvement such as preseptal cellulitis or an orbital abscess, osteomyelitis, mucoceles, and, rarely, intracranial complications.[2] Most patients require long-term care and treatment of comorbidities, such as allergies or asthma, to prevent recurrent disease.[3][4][5][6]

CRS is a complex disease with multiple risk factors. Common predisposing factors for CRS include anatomic abnormalities, allergic and nonallergic rhinitis, asthma, nasal polyps, impaired mucociliary clearance, immunologic disorders, recurrent viral upper respiratory tract infections, dental disease, systemic inflammatory diseases, or tumor obstruction. Etiologies can be categorized as follows: Systemic Genetic diseases: cystic fibrosis Immunodeficiency: eg, human immunodeficiency virus Autoimmune diseases Gastroesophageal reflux Aspirin-exacerbated respiratory disease: Samter triad Granulomatosis with polyangiitis (formerly Wegener granulomatosis) Eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss vasculitis) Sarcoidosis [7][8] Local Host Factors Sinonasal anatomic variations Trauma Foreign bodies Neoplasm Benign: nasal polyps Malignant Iatrogenic causes: postoperative complications or scarring Environmental and Microbial Allergens: dust mites, molds Pollutants: airborne irritants, cigarette smoke, or other toxins Biofilms [9] Bacterial infection [5][10][11] Fungal infection [12]

Chronic rhinosinusitis affects all age groups, and 12% of the adult United States (US) population has experienced CRS in the past 12 months.[13] CRS has a high impact on the quality of life. Antibiotics are often used for rhinosinusitis, but widespread use is associated with high costs, adverse effects, and antimicrobial resistance.[14] According to the CDC National Center for Health Statistics, the epidemiology for adults 18 and older in the US, 2018, has the following characteristics: Sex: Radiologic sinus inflammation, symptoms of CRS, and sinus opacification are more common in women.[15] The highest incidence of CRS is found among White women (15.4%). Race/ethnicity: The prevalence of sinusitis was 10.5% for Native American or Alaskan Natives, 6.6% for Asian, 10.8% for Black, 8% for Hispanic or Latino, 11.7% for White, and 12.5% for patients of mixed race or ethnicity. Education: Patients without a high school diploma had a lower prevalence (8.6%). Conversely, those with higher education levels had prevalence rates ranging from 11.0% to 13.4% (higher education may be associated with better access to healthcare and diagnosis). Employment: Patients who had never been employed had a sinusitis prevalence of 8.7%, whereas those who were currently unemployed but had been employed previously had a prevalence of 13.4%. The prevalence among employed individuals was 10.2%. These higher figures among the currently unemployed may reflect the impact of chronic sinusitis on quality of life and productivity. Region: Geographic differences within the US are consistent across studies, with the Southern US showing the highest rates of sinusitis diagnosis (13.4%). In comparison, rates were 9.9% in the Northeast, 9.4% in the West, and 10.5% in the Midwest in 2018.[16][17][18][19]

Chronic rhinosinusitis is likely a chronic inflammatory disease influenced by several factors. Many people associate CRS with sinus infections, as it often occurs after an episode of acute sinusitis that is either untreated or does not respond to medical treatment. However, CRS is frequently triggered by a disruption of the intrinsic mucociliary transport system within the paranasal sinuses, leading to the stagnation of secretions. The causes of obstruction are either mechanical obstruction at the osteomeatal complex or mucosal edema, often due to rhinitis. The stagnation of mucus provides a rich environment for the growth of pathogens, typically aerobic bacteria, but may include mixed flora and fungi.[20] CRS in children may represent a distinct spectrum of pathophysiology from that in adults.[21] Additional factors that may contribute to the inflammatory process in CRS include: Allergy [22] Immune deficiency [23] Biofilms [9] Osteitis [24] Anatomical and physiologic variations Superantigens that trigger excessive stimulation of T lymphocytes [25] Fungi [26] Aspirin sensitivity (Samter triad) [27][28] Lastly, whether CRS is associated with polyps or not, it is characterized by inflammation, vasodilation, growth, and changes in glandular activity. Activation of nerve endings triggers neurogenic inflammation and morphologically identifiable mucosal remodeling.[29]

The allergic polyp is the most common type of nasal polyp, accounting for 86% of cases. The cause of nasal polyps is unknown, but they are characterized histologically by significant goblet cell hyperplasia, thickening of the basal membrane with hyalinization, the presence of eosinophils and mast cells in the stroma, and edema.[30] The surface epithelium of allergic-type nasal polyps can be intact, completely denuded, or partially denuded respiratory mucosa. The epithelium may also show various changes, including basal-layer hyperplasia, squamous metaplasia, goblet-cell hyperplasia, and infiltration by inflammatory cells, especially eosinophils.[31]

Clinicians should obtain a thorough patient history because CRS signs and symptoms overlap substantially with those of other conditions, most commonly viral upper respiratory tract illness, chronic rhinitis, allergic rhinitis, acute sinusitis, or recurrent acute sinusitis. The poor correlation among symptoms, endoscopic findings, and radiographic images further complicates the diagnosis of CRS. CRS may develop over months to years, and is often misdiagnosed because patients typically present without pain or fever. CRS is characterized by at least 12 weeks of symptoms, including 2 or more of the following: Thick or discolored drainage (either anterior, posterior, or both) Nasal congestion Facial pain, pressure, fullness Decreased sense of smell More subtle symptoms may include postnasal drip, headache, chronic unproductive cough (especially in children), sore throat, halitosis, malaise, anorexia, visual changes, sneezing, decreased hearing, ear fullness, dizziness, unexplained taste changes, or fevers. The patient's past medical, surgical, trauma, and family histories may also provide important diagnostic clues. Additionally, a history of allergic, immunologic, or metabolic diseases should be assessed (see Image. Lund-Mackay Scoring System for Staging Sinusitis). The next step in the evaluation is a physical examination to document inflammation and obstruction as part of a complete head and neck examination. Key points to consider include: Sinus palpation for tenderness or swelling (subjective) Transillumination of the maxillary or frontal sinuses (may be of limited value) Anterior rhinoscopy Limited view of the anterior portion of the nose, depending on the level of obstruction May be improved with a topical decongestant Nasal endoscopy with or without video Provides anterior, middle, and posterior views of the nasal mucosa, nasal septum, and turbinates Access to the osteomeatal complex Enables a culture of purulent secretions Assessment for obstructions or nasal polyps Ocular examination Extraocular movements or cranial nerve palsies Gross visual disturbances Conjunctival examination Lacrimation Enopthalmus or exopthalmus Otologic examination Assess for serous otitis media, which may indicate nasopharyngeal mass or obstruction Oral and oropharyngeal examination Postnasal drainage Palate integrity or masses in the nasopharynx Dental disease Laryngeal examination (fiberoptic laryngoscopy) Assess for laryngeal-pharyngeal reflux

Lacrimation Enopthalmus or exopthalmus Otologic examination Assess for serous otitis media, which may indicate nasopharyngeal mass or obstruction Oral and oropharyngeal examination Postnasal drainage Palate integrity or masses in the nasopharynx Dental disease Laryngeal examination (fiberoptic laryngoscopy) Assess for laryngeal-pharyngeal reflux Pulmonary examination Assess for upper and lower airway disease Neurologic examination Assess cranial nerves

The evaluation of CRS depends on the suspected underlying pathology and may include laboratory studies, radiographic imaging, cultures, or biopsy. Laboratory Studies Routine laboratory testing has limited value unless the history suggests there is an underlying disease process or comorbidity. Allergy and immune function testing results may vary with individual patient characteristics; however, they should be used to support the diagnosis of CRS rather than to establish it.[32] Common tests include: Allergy testing: Radioallergosorbent assay test or skin testing [33] Immunological testing: Serum immunoglobulin (Ig) and IgG subclasses [34] Total immunoglobulin E levels in allergic fungal sinusitis [35][36] HIV testing  [37] Radiographic Imaging Plain radiography: Limited value [38] May show mucosal thickening or sinus opacification Neither sensitive nor specific for CRS Air-fluid levels are rarely seen in CRS CT scan: Multiplanar contrast-enhanced Criterion standard [39] Evaluates opacification of sinuses or thickened mucosal membranes (See Image. Acute Sinusitis). Detects inflammatory disease, nasal polyps, and mucoceles Assesses sinus ostial obstruction, such as the osteomeatal complex Detects tumors or bony defects, including sclerosis, septations, erosions, and bowing Assesses the orbits, cribiform plates, and optic canal Evaluates dental and palatal pathologies Used for planning and is valuable for image-guided procedures MRI scan Best for soft-tissue contrast Complementary to a CT scan [40] Useful to assess tumors, orbital and intracranial complications, and fungal sinusitis Cultures Nasal swab cultures: Little to no diagnostic value Blood cultures: Severe cases of recurrent acute exacerbations of CRS [41] Endoscopically directed middle meatus cultures: Sensitivity of 80.9% and a specificity of 90.5% [42] Maxillary sinus tap culture (inferior meatal puncture): Used less often since it may be less accurate than a middle meatus culture. Helpful when a middle meatus culture is not feasible, such as in an intubated patient Biopsy Evaluates presumed ciliary dysfunction, along with the sweat test for cystic fibrosis [43] Excludes inverting papilloma or malignant tumor Nasal cytology This may provide diagnostic value for the inflammatory response, but it is more useful in noninfectious rhinitis than in CRS.[44] Newer Methods Thermography in the diagnosis of acute inflammation [45][46]

Accurate diagnosis remains the most challenging aspect of CRS.[47] While supportive care can treat various nasal and sinus problems, CRS treatment must be precise and personalized for each patient. Unfortunately, some patients are underdiagnosed, overdiagnosed, or misdiagnosed with CRS. Not every patient shows the same signs and symptoms, has the same risk factors, responds similarly to treatments, or achieves long-term relief and improved quality of life. Therefore, all patients with CRS need both immediate and ongoing care tailored to their individual needs. Clinicians should provide a clear rationale for any treatment intervention, whether medical or surgical. Treatment should be directed to improving sinus drainage and outflow, enhancing mucociliary clearance, eradicating inflammation and infection, and improving access of topical therapies to the inflamed mucosa.[48] Supportive Care Humidification and hot compresses Over-the-counter analgesics, such as nonsteroidal anti-inflammatory drugs or acetaminophen Topical intranasal corticosteroids Nasal saline irrigation Topical or systemic decongestants (sympathomimetics) Antihistamines generally have no role unless there is an allergic component Guaifenesin (expectorant) Mucolytics Control of Contributing Factors Upper respiratory tract illnesses Allergy and asthma Environmental triggers such as dust, dust mites, pet dander, cigarette smoke, toxins, or pollutants Gastroesophageal and laryngopharyngeal reflux Immunodeficiency Cystic fibrosis Corticosteroids Oral corticosteroid therapy followed by topical corticosteroid therapy may be effective in reducing nasal polyp size and improving olfaction.[49] These confer synergistic benefits when combined with antibiotics.[50] Topical intranasal corticosteroid delivery systems are effective and well-tolerated.[51][52] Antibiotics, Antifungals, and Biofilms The role of antibiotics in the treatment of CRS is debatable; their benefit may be transient and attributable to anti-inflammatory effects.[53] A biofilm is a community of bacteria or fungi that surrounds itself with a protective extracellular matrix. Biofilms are present in both healthy individuals and CRS patients, so their clinical significance remains uncertain. Biofilms may influence CRS treatment strategies.[9] Nasal irrigation with aminoglycosides should be avoided due to the risk of systemic absorption and toxicity; topical antifungals are not beneficial.[48][54]

A biofilm is a community of bacteria or fungi that surrounds itself with a protective extracellular matrix. Biofilms are present in both healthy individuals and CRS patients, so their clinical significance remains uncertain. Biofilms may influence CRS treatment strategies.[9] Nasal irrigation with aminoglycosides should be avoided due to the risk of systemic absorption and toxicity; topical antifungals are not beneficial.[48][54] Treatment with topical antibiotics provides little if any benefit.[55] The initial choice of antibiotics is empiric, and cultures may be helpful in recalcitrant cases: An exacerbation of acute sinusitis could be treated with coverage for β-lactamase–producing organisms. Methicillin-resistant Staphylococcus aureus coverage is necessary in some cases due to ongoing antibiotic exposure. S aureus colonization is possible in patients with CRS with nasal polyps, and doxycycline therapy has been effective.[56] In patients without nasal polyps, a macrolide antibiotic may be effective when used for 3 months.[57] Antibiotic resistance is a risk in patients with CRS due to extended antibiotic use.[58] Dupilumab and Other Biologic Agents The Food and Drug Administration (FDA) approved dupilumab in June 2019 for the treatment of inadequately controlled severe chronic rhinosinusitis with nasal polyps (CRSwNP) in adults.[59] Dupilumab is a humanized monoclonal antibody that inhibits interleukin-4 (IL-4) and IL-13 signaling by specifically binding to the IL-4Rα subunit.[60] Dupilumab and other biologic agents are effective in treating refractory CRSwNP, but are one component of a broader management strategy.[61] Endoscopic sinus surgery may be comparable to biologic agents in controlling CRS symptoms. Traditional medical and surgical treatments may cost substantially less than biologic agents. Surgery External open approach (traditional) May be combined with several approaches, including functional endoscopic sinus surgery Caldwell-Luc External ethmoidectomy Frontal sinus osteoplastic flap Frontal sinus trephine Weber-Ferguson incision for large tumors Functional endoscopic sinus surgery Involves the immediate removal of polyps, mucosal thickening, allergic mucin, or fungal debris to halt disease progression and enlarge the sinus ostium Removes the physical obstruction in the sinuses and facilitates drainage.

Frontal sinus osteoplastic flap Frontal sinus trephine Weber-Ferguson incision for large tumors Functional endoscopic sinus surgery Involves the immediate removal of polyps, mucosal thickening, allergic mucin, or fungal debris to halt disease progression and enlarge the sinus ostium Removes the physical obstruction in the sinuses and facilitates drainage. Improves sinonasal outflow tract dimensions and facilitates mucociliary clearance and topical medication application. Eliminates the source of the pressure atrophy and prevents the progression of bone erosion. Removes the osteitic bone that contributes to sinonasal obstruction. Early surgical intervention is necessary because medical interventions cannot correct sinus obstruction or allow the egress of stimulating antigens [62][63] Technical options Video with or without recording Endoscopy, 0 to 70° angle Image-guided functional endoscopic sinus surgery [64] Computer-assisted surgery may not improve outcomes, but it may reduce complications.[65] Procedural components Endoscopic uncinectomy Ethmoidectomy (anterior or posterior) Maxillary antrostomy Sphenoidotomy Frontal sinus opening Balloon sinuplasty [66][67] Minimally invasive treatment Approved by the FDA in 2005 Patients with frontal or sphenoid disease are more likely to undergo balloon sinuplasty or a hybrid procedure

The differential diagnosis of CRS includes: Recurrent acute sinusitis Acute bacterial sinusitis Viral upper respiratory tract illness Allergic and nonallergic rhinitis Facial neuralgia Migraine or other primary headache disorders Dental infection Periodontal abscess Nasal and sinus tumors Inverting papilloma Aspirin and nonsteroidal anti-inflammatory drug sensitivity Foreign body Fungal sinusitis Juvenile nasopharyngeal angiofibroma Cystic fibrosis

Despite the complexity of host factors and their significant impact on health-related quality of life, the prognosis for CRS is favorable for most patients. Treatment of CRS improves health-state utility values and significantly reduces symptom burden.[68] Long-term results of sinus surgery for CRS show significant improvement in quality of life at 6 months postoperatively, with benefits persisting for nearly 11 years.[69] Long-term medical therapy appears to improve outcomes and reduce the need for additional surgery. Results from many long-term studies show improvements in sinusitis symptoms, sleep quality, fatigue, and fibromyalgia symptoms.[70][71]

Prompt investigation of complex sinusitis is essential to prevent debilitating and fatal sequelae.[72] Complications might include: Noninfectious: Fatigue and reduced concentration Absenteeism and reduced productivity Nasal obstruction Sleep disturbance Asthma exacerbations Anosmia and dysgeusia Infectious: Chronic infection with multiple pathogens resistant to medical therapy Osteomyelitis Fungal sinusitis Mucocele Localized spread Laryngitis Pharyngitis Bronchitis Pneumonia Ocular: Periorbital cellulitis Orbital cellulitis Orbital abscess Dacryocystitis Surgical complications Loss of vision Ophthalmopegia Intracranial: Cerebrospinal fluid leak Meningitis Mastoiditis Subdural empyema Brain abscess Cavernous sinus thrombosis

Possible consultations include pulmonary, gastroenterology, neurology, neurosurgery, ophthalmology, allergy/immunology, infectious disease, neuroradiology, pediatrics, oncology, and audiology specialists.

Long-term management of CRS is a shared responsibility among patients, families, and clinicians. While not all upper respiratory illnesses present as acute exacerbations of CRS, many patients experience chronic inflammation, nasal and sinus outflow blockage, and ongoing symptoms. Treatment often involves a combination of medical therapy, revision surgery, allergy treatment if needed, and biologics such as dupilumab or omalizumab if necessary. Patients with CRS, especially those who have previously undergone functional endoscopic sinus surgery, are advised to seek care if symptoms recur or persist, as they may benefit from a comprehensive endoscopic evaluation and possible repeat imaging. Other patients require reevaluation while being treated for underlying comorbidities.

CRS is associated with several complications and underlying etiologies that require ongoing evaluation and long-term care: Although CRS affects more than 10% of US adults, accurate diagnosis can be challenging. Despite advancements in surgical techniques and new medical therapies, treating CRS should include a patient-centered approach, as individual treatment needs vary. Patients, families, and clinicians should understand that managing CRS might require lifelong attention and support.

Providing patient-centered care for individuals with CRS requires a collaborative effort among healthcare professionals, including clinicians, nurses, pharmacists, and other specialists. Healthcare professionals must have a strong understanding of nasal and sinus anatomy and physiology, along with the clinical skills needed to make accurate diagnoses. This knowledge includes proficiency in sinonasal endoscopy, interpretation of radiological and pathological findings, investigation of underlying systemic illnesses, and management of complex sinonasal issues. A strategic approach balances clinical expertise and evidence-based guidelines with patient expectations to create personalized care plans. Ethical communication among team members is paramount. An otolaryngologist must be available for patients experiencing a relapse and maintain vigilance in partnership with patients and other healthcare professionals, especially if the patient needs immediate follow-up care. Open and transparent communication facilitates rapid diagnosis, prevents complications, and hastens patient care. Patient preferences are central to shared decision-making, as there may be multiple approaches to both short- and long-term sinonasal disease. Education and training keep the healthcare team up to date on best practices. Ongoing professional development ensures that healthcare professionals are equipped to respond to individual patient needs. Clinicians should be discouraged from antibiotic overuse, repeated surgery, and systemic corticosteroid use in patients who may have alternative options such as biologic therapy. A patient-centered approach prioritizes the patient's well-being and preferences in all decisions. In managing CRS, an interprofessional team ensures a comprehensive response, minimizes complications, and prioritizes patient safety and quality care.