Rhinosinusitis is a mucosal inflammation of both the paranasal sinuses and adjacent nasal cavities. Viral infection is the most common cause of acute rhinosinusitis (ARS); bacterial and fungal infections also occur. The characteristic symptoms of rhinosinusitis are purulent rhinorrhea, nasal obstruction, and facial pain. ARS is often self-limiting, but antibiotic therapy may be indicated in the case of suspected or diagnosed bacterial superinfection. Imaging and endoscopy are reserved for patients with recurrent sinusitis, red flags for rhinosinusitis, or certain risk factors (e.g., immunosuppression). Rarely, the infection may spread to the soft tissues, bone, vascular system, and/or central nervous system. Chronic rhinosinusitis (CRS), a chronic inflammatory state similar to asthma, lasts at least 12 weeks and may be complicated by bacterial exacerbations or chronic fungal infections. Diagnosis is confirmed by findings of inflammation on imaging, anterior rhinoscopy, or nasal endoscopy. Underlying comorbidities, such as allergy, cystic fibrosis, and immunodeficiency, should be ruled out. First-line treatment of CRS is intranasal steroids and nasal irrigation for symptomatic relief. Patients with persistent symptoms may require surgery.
- Pansinusitis: inflammation of all sinuses on one or both sides
- Acute sinusitis: inflammation of the sinuses for < 4 weeks
- Subacute sinusitis: progressive symptoms of sinus inflammation occurring over 4–12 weeks; represents a transition from acute to chronic infection
- Chronic sinusitis: persistent symptoms of sinus inflammation > 12 weeks
- Recurrent acute sinusitis: four or more separate episodes of acute sinusitis that occur within 1 year, with at least 8 weeks of symptom resolution between episodes
- Rhinosinusitis: simultaneous inflammation of the nasal mucosa and sinuses
- Route of transmission: droplet transmission, particularly in winter months
- Preexisting viral upper respiratory tract infection (URTI): most common; leads to superimposed bacterial infections
- Ventilation disorders of the sinuses
- Foreign body lodged in the nasal cavity (particularly seen in children).
- Odontogenic infection: leads to unilateral maxillary sinusitis
- mucosa : spread of pathogens via nasal
- Bronchial asthma
- Analgesic (NSAIDs, aspirin) intolerance
- Sinusitis is triggered by three factors: obstruction of sinus drainage pathways (sinus ostia) due to mucosal edema, ciliary impairment, and altered mucus quantity and quality → stasis of secretions inside the sinuses → proliferation of various pathogens; → sinusitis
- Recurrent, untreated/complicated acute sinusitis may lead to chronic sinusitis.
- Unspecific symptoms: fever; (∼ 50% of cases), headaches, general malaise, myalgia
Facial pain/pressure, erythema, and swelling over the affected area due to inflammation
Maxillary sinuses are most commonly affected.
- Since maxillary ostium, which drains the maxillary sinuses, is located posteriorly and medially near the roof of the maxillary sinus, secretions are drained against the pull of gravity (i.e., upwards), causing secretions to accumulate and increasing the susceptibility to infection.
- Inflammation of mucosa → sinus ostial blockage → drainage into the ostiomeatal complex → ↑ mucus production by the nasal mucosa → congestion and swelling of the nasal passages → sinus cavity hypoxia and mucus retention → ↓ function of nasal cilia → ↓ transportation of mucus and debris from the nose → creation of ideal conditions for bacterial growth → ↑ susceptibility to infection
- Manifests with pain in jaw region (mimics dental pain)
- Frontal sinuses: pain in the lower forehead
- Ethmoidal sinuses: pain in the nasal bridge region or retroorbital pain
- Sphenoid sinuses: located in the sphenoid bones near the optic nerve and pituitary gland
- Maxillary sinuses are most commonly affected.
- Transillumination may show opacification.
- Acute viral rhinosinusitis
- Acute bacterial rhinosinusitis
- Fungal rhinosinusitis: See “ .” 
Chronic rhinosinusitis can manifest acutely with exacerbation of symptoms or take an insidious course with low-grade symptoms persisting over months to years.
- Signs of inflammation
- Chronic fungal rhinosinusitis: See “Fungal rhinosinusitis” below.
- Chronic rhinosinusitis with nasal polyps: Pathogenesis is not fully understood, but there is an association with asthma, allergic rhinitis, and cystic fibrosis. 
- Chronic rhinosinusitis without nasal polyps: Pathogenesis is associated with anatomical abnormalities (e.g., septal deviation, tumors) and dental disease (i.e., sinusitis of dental origin).
Subtypes and variants
Nasal polyps 
- Definition: benign lesions of the nasal mucosa or paranasal sinuses due to chronic mucosal inflammation
- Risk factors
- Clinical features
- Special form: choanal polyp
- Differential diagnosis:
- Topical or systemic glucocorticoids
- Resection of polyps if symptomatic despite medical therapy but recurrence is common
Primary ciliary dyskinesia 
- Definition: rare autosomal recessive disorder characterized by absent or dysmotile cilia caused by a defect in the dynein arm of microtubules
- Chronic productive cough
- Recurrent otitis, sinusitis, and nasal polyps
- Conductive hearing loss
- Displaced heart sounds (as a result of dextrocardia)
- Infertility in men due to decreased sperm motility as a result of defective flagella
- Reduced fertility in women (and rarely ectopic pregnancy) due to defective cilia in fallopian tubes
- Kartagener syndrome: classic triad of situs inversus, recurrent sinusitis, and bronchiectasis
- Treatment: depends on individual clinical presentation and course
Fungal rhinosinusitis (FRS) 
- Definition: rhinosinusitis caused by a fungal pathogen 
- Duration: acute (< 4 weeks) and chronic (≥ 12 weeks)
- Histopathology: invasive (e.g., acute invasive fungal rhinosinusitis) or noninvasive (e.g., fungal ball, allergic fungal rhinosinusitis, etc.)
- Risk factors
- General symptoms: See “ .”
- Noninvasive fungal rhinosinusitis 
- Acute invasive fungal rhinosinusitis : epistaxis and dark ulcers on the septum, palate and turbinates; may be acutely ill with altered mental status 
- CT: Possible findings include fungal balls, bony erosions, and extra sinonasal spread. 
- MRI: may be indicated to assess for cranial or orbital spread, especially in acute invasive fungal rhinosinusitis
- Nasal endoscopy: Findings indicating acute invasive fungal rhinosinusitis include pale mucosa, dark necrotic areas, and crusting/ulcers.
- Fungal culture
- An ENT specialist should manage all cases of suspected fungal rhinosinusitis.
- Patients with acute invasive fungal rhinosinusitis
General principles 
- Acute viral/bacterial rhinosinusitis is a clinical diagnosis.
Chronic rhinosinusitis diagnosis is confirmed by findings of inflammation on one of the following:
- CT scan 
- Direct visualization
- Additional studies should be performed in the following cases:
A clinical diagnosis of chronic sinusitis should be confirmed with objective documentation of sinonasal inflammation, which can be accomplished via anterior rhinoscopy, nasal endoscopy, or CT scan. 
Red flags for rhinosinusitis 
Patients with red flag symptoms require urgent imaging; ENT may recommend further diagnostic studies.
- Focal neurologic deficits (including cranial nerve palsies)
- Severe headache
- Facial edema
- Altered mental status
- Ophthalmic complications (e.g., blurred vision, proptosis, impaired ocular movements)
- Fever > 39°C (102°F) and/or that lasts > 3 days
- Symptoms not improving despite adequate antibiotic therapy
CT maxillofacial with or without IV contrast
- Indications 
- Findings may include signs of:
- Rhinosinusitis: opacification, mucosal thickening, air-fluid levels, soft tissue swelling 
- Complications: spread beyond the sinuses
- Underlying causes of CRS: e.g., anatomic abnormalities, osteomeatal obstruction, polyposis
- Aggressive fungal infection or neoplasm: e.g., osseous destruction, extrasinus extension, local invasion 
- MRI with and without IV contrast: can be used to evaluate for intracranial or intraorbital involvement or to differentiate polyps from tumors 
- No longer recommended due to limited sensitivity and specificity
- May show sinus opacification and air-fluid levels
- Indications: evaluation of complicated rhinosinusitis, recurrent ARS, or CRS
Anterior rhinoscopy may miss smaller polyps and/or more posterior disease because it only visualizes the anterior third of the nasal cavity. If anterior rhinoscopy findings are normal, perform nasal endoscopy. 
Evaluation for comorbid conditions: Perform for patients with recurrent ARS and CRS. 
- Allergic rhinitis: Consider . 
- : Perform .
- : Perform . 
- Otitis media, bronchiectasis, or pneumonia
- Rheumatologic disorders: Choice of further studies depends on clinical features (e.g, diagnostic evaluation for sarcoidosis, workup for vasculitic syndrome). 
- Bacterial/fungal cultures: Request in cases of treatment failure.
- Biopsy (endoscopic or surgical): to identify an underlying condition (including malignancies) and to enable classification 
Diagnostic criteria for acute rhinosinusitis 
Purulent nasal drainage with at least one of the following:
- Nasal obstruction
- Facial pain or pressure
- Duration: ≤ 4 weeks
Classification of acute rhinosinusitis 
Viral rhinosinusitis (VRS)
- Clinical features of ARS that improve within 10 days
- Symptoms do not worsen.
Acute bacterial rhinosinusitis (ABRS)
- Clinical features of ARS that do not improve within 10 days 
- Symptoms initially improve but then worsen within 10 days (double worsening).
- Clinical features of ARS that do not improve within 10 days 
- Recurrent acute rhinosinusitis: ≥ 4 episodes of ABRS per year with symptom-free intervals
Diagnostic criteria for chronic rhinosinusitis 
- At least two of the following for ≥ 12 weeks:
- PLUS inflammation identified through at least one of the following:
Approach to treatment of rhinosinusitis 
- Uncomplicated viral rhinosinusitis is usually self-limiting.
- Uncomplicated ABRS
- Complications of ABRS: Start IV antibiotics and consult ENT.
- Acute invasive fungal rhinosinusitis: Immediately consult ENT and consider ID consult for antifungal therapy (e.g., amphotericin B) and surgery.
- Episode of recurrent ARS: Treat as ABRS initially and involve ENT for further management. 
- Treat acute exacerbations as ABRS. 
- Advise nasal saline irrigation for symptomatic relief.
- Treat the underlying inflammation with corticosteroids. 
- All patients: intranasal for at least 8–12 weeks 
- Patients with nasal polyps and severe symptoms: Consider addition of a short course (3 weeks) of oral therapy. 
- If there is no response to medical management, or if are present, refer to ENT.
Symptomatic treatment 
The following options may be offered to all patients with rhinosinusitis.
- Nasal saline irrigation
- Oral analgesics, e.g., ibuprofen or acetaminophen
- Intranasal steroids, e.g., mometasone  
- Decongestants, e.g., oxymetazoline
Antibiotic treatment 
- First-line antibiotic therapy: amoxicillin, with or without clavulanate
- Usual oral treatment duration for adults: 5–10 days 
- Consider risk factors for treatment failure when choosing an appropriate antibiotic.
- Increased risk of bacterial resistance
- Severity of infection
- Patient factors, including smoke exposure, age > 65 years, and comorbidities, e.g., diabetes or cardiac/hepatic/renal disease
- In case of treatment failure, switch to one of the recommended antibiotic regimens from a different class with broader coverage.
|Antibiotic treatment in acute bacterial rhinosinusitis (ABRS) |
|Adults||Children (< 18 years)|
Surgical treatment 
- Local spread
- Spread to the orbit
- Intracranial spread
- Systemic complications
Orbital and intracranial necrotic spread is especially common in invasive fungal sinusitis.
We list the most important complications. The selection is not exhaustive.