# Acute and Chronic Rhinosinusitis: Diagnosis and Medical Management

## Overview
Rhinosinusitis is one of the most common conditions in otolaryngology practice, affecting approximately 12% of adults annually. Accurate differentiation of viral, bacterial, and chronic forms is essential to guide appropriate therapy and avoid antibiotic overuse. Evidence-based management follows established guidelines from EPOS and AAO-HNS.

## Definitions
**Acute rhinosinusitis (ARS)**: symptoms for up to 4 weeks. Viral ARS (common cold): symptoms for <10 days without worsening. Acute bacterial rhinosinusitis (ABRS): symptoms >10 days without improvement, or worsening after initial improvement ("double sickening"). **Subacute rhinosinusitis**: symptoms lasting 4-12 weeks. **Chronic rhinosinusitis (CRS)**: symptoms persisting >12 weeks with objective evidence (endoscopic findings or CT changes). **Recurrent acute rhinosinusitis**: 4 or more episodes per year, each lasting 7-10 days, with complete resolution between episodes.

## Pathophysiology

### Ostiomeatal Complex Obstruction
Mucosal inflammation causes sinus ostium obstruction, Impaired mucociliary clearance and ventilation, Stagnation of secretions, decreased oxygen tension, Secondary bacterial infection in ABRS.

### Mucociliary System
Ciliated pseudostratified columnar epithelium lines sinuses. Cilia beat at 10-15 Hz; mucus blanket has sol (periciliary) and gel (surface) layers. Clearance patterns: maxillary sinus drains toward the natural ostium (not the most dependent point); frontal sinus drains along the interfrontal septum and posterior wall.

### Microbiology
**Viral ARS**: rhinovirus (most common), coronavirus, influenza, parainfluenza, adenovirus. **ABRS**: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis (especially in children). **CRS**: often polymicrobial; Staphylococcus aureus (including MRSA), anaerobes, Pseudomonas (especially in cystic fibrosis). Biofilm formation implicated in refractory CRS.

## Diagnosis of Acute Rhinosinusitis

### Clinical Criteria (AAO-HNS)
Must have symptoms of purulent nasal drainage PLUS nasal obstruction or facial pain/pressure/fullness. Duration and course distinguish viral from bacterial: Viral: resolves within 10 days. Bacterial: symptoms >10 days without improvement, OR worsening after 5-7 days (double sickening), OR severe onset (high fever >39C and purulent drainage for 3-4 days).

### Imaging
NOT recommended for uncomplicated ABRS (clinical diagnosis). CT scan indicated for: suspected complications, recurrent ARS, pre-surgical planning. Incidental mucosal thickening on CT is extremely common and does not equal sinusitis.

### Nasal Endoscopy
Not required for diagnosis of uncomplicated ARS. Useful for CRS: mucopurulent discharge from middle meatus, polyps, mucosal edema.

## Medical Management of ABRS

### Antibiotic Therapy
**First-line**: amoxicillin-clavulanate (500/125 mg TID or 875/125 mg BID for 5-7 days). High-dose (2g/125mg BID) if: risk of resistance, recent antibiotics, immunocompromised, severe infection. **Penicillin allergy**: doxycycline or respiratory fluoroquinolone (levofloxacin, moxifloxacin). **Second-line (treatment failure after 72 hours)**: high-dose amoxicillin-clavulanate, respiratory fluoroquinolone, or clindamycin. Duration: 5-7 days (recent evidence supports shorter courses). Watchful waiting is an option for mild uncomplicated ABRS per AAO-HNS guidelines.

### Adjunctive Therapy
**Intranasal corticosteroids**: recommended for symptom relief; monotherapy option for mild ABRS. **Saline irrigation**: hypertonic or isotonic; improves mucociliary clearance. **Oral decongestants**: pseudoephedrine; short-term use (<3 days for topical oxymetazoline). **Analgesics**: acetaminophen or NSAIDs for pain. NOT recommended: oral antihistamines (unless allergic rhinitis coexists), mucolytics (limited evidence).

## Complications of Acute Sinusitis

### Orbital Complications (Chandler Classification)

| Stage | Name | Key Features | Management |
|-------|------|--------------|------------|
| I | Preseptal cellulitis | Edema anterior to orbital septum; no visual changes | IV antibiotics |
| II | Orbital cellulitis | Proptosis, chemosis; limited EOM | IV antibiotics; close monitoring |
| III | Subperiosteal abscess | Collection along lamina papyracea; globe displacement | Surgical drainage |
| IV | Orbital abscess | Intraconal collection; ophthalmoplegia; vision loss | Urgent surgical drainage |
| V | Cavernous sinus thrombosis | Bilateral findings; CN palsies; AMS | ICU; anticoagulation; surgery |

**Stage I**: Preseptal cellulitis -- edema and erythema anterior to orbital septum; no visual changes. **Stage II**: Orbital cellulitis -- diffuse orbital edema; proptosis, chemosis; may have limited EOM. **Stage III**: Subperiosteal abscess -- collection between lamina papyracea and periorbita; medial orbital displacement. **Stage IV**: Orbital abscess -- collection within the orbital soft tissue; ophthalmoplegia, vision loss. **Stage V**: Cavernous sinus thrombosis -- bilateral orbital findings, cranial nerve palsies, mental status changes. Management: IV antibiotics; CT with contrast; urgent surgical drainage for abscess or visual compromise.

### Intracranial Complications
Meningitis, epidural abscess, subdural empyema, brain abscess. Frontal sinus source most common ("Pott puffy tumor": frontal bone osteomyelitis with subperiosteal abscess). Require neurosurgical consultation and prolonged IV antibiotics.

## Chronic Rhinosinusitis (CRS)

### Diagnostic Criteria
Symptoms >12 weeks: nasal obstruction, mucopurulent drainage, facial pain/pressure, hyposmia. PLUS objective evidence: endoscopic findings (polyps, mucosal edema, purulent discharge) OR CT changes (mucosal thickening, air-fluid levels). CT sinus is the imaging standard; Lund-Mackay scoring system (0-24 points; each sinus scored 0-2 per side; OMC 0 or 2).

### CRS Phenotypes
**CRS without nasal polyps (CRSsNP)**: more neutrophilic inflammation, Th1-dominant; may have bacterial biofilms. **CRS with nasal polyps (CRSwNP)**: eosinophilic, Th2-dominant inflammation; associated with asthma and aspirin sensitivity (Samter triad). Endotyping increasingly important for biologic therapy selection.

### CRS Endotypes
Type 2 inflammation: eosinophilic, elevated IgE, IL-4, IL-5, IL-13; responsive to biologics. Non-type 2: neutrophilic or mixed; less responsive to current biologics. Biomarkers: tissue eosinophils, serum IgE, periostin.

### Medical Management of CRS
**Saline irrigation**: high-volume (240 mL) preferred; mainstay of therapy. **Intranasal corticosteroids**: first-line pharmacotherapy; daily use. Budesonide irrigation (off-label): 0.5 mg/2 mL in 240 mL saline; evidence for benefit especially in CRSwNP and post-FESS. **Short-course oral corticosteroids**: for CRSwNP exacerbations; prednisone 0.5 mg/kg for 5-14 days; limit to 2-3 courses per year. **Antibiotics in CRS**: culture-directed for acute exacerbations; macrolide therapy (clarithromycin 250 mg daily for 12 weeks) for CRSsNP with low IgE -- anti-inflammatory properties. **Biologics**: discussed in Topic 14 (CRSwNP and biologics). **Allergy management**: if concurrent allergic rhinitis, immunotherapy may improve CRS outcomes.

### Failure of Medical Therapy
Defined as persistent symptoms despite appropriate maximal medical therapy for at least 8-12 weeks. Indication for functional endoscopic sinus surgery (FESS) -- discussed in Topic 13.

<image>Coronal CT scan of the paranasal sinuses demonstrating bilateral maxillary sinus opacification and ethmoid mucosal thickening consistent with chronic rhinosinusitis. The ostiomeatal complex is obstructed bilaterally. Lund-Mackay scoring regions are highlighted with labels for each sinus (maxillary, anterior ethmoid, posterior ethmoid, sphenoid, frontal) and the ostiomeatal complex on each side. A scoring key shows the 0-2 grading for each region.</image>

<image>Endoscopic photograph of the left middle meatus showing findings of chronic rhinosinusitis: mucopurulent discharge emanating from the middle meatus, edematous middle turbinate with polypoid changes, and inflamed uncinate process. Normal anatomy is shown in a comparison panel on the right for reference, with the uncinate process, ethmoid bulla, and hiatus semilunaris labeled.</image>

<image>Chandler classification of orbital complications of sinusitis illustrated in five axial CT scan diagrams. Stage I shows preseptal soft tissue swelling anterior to the orbital septum. Stage II shows diffuse orbital fat stranding. Stage III shows a lenticular subperiosteal collection along the medial orbital wall with globe displacement. Stage IV shows an intraconal abscess. Stage V shows bilateral findings with cavernous sinus enhancement and expansion. The lamina papyracea, medial rectus, and orbital septum are labeled in each panel.</image>

## Clinical Pearls
The most important distinction is viral vs. bacterial ARS: antibiotics are NOT indicated for viral ARS (vast majority of cases). "Double sickening" -- initial improvement followed by worsening -- is the most specific clinical indicator of ABRS. Amoxicillin-clavulanate (not amoxicillin alone) is first-line for ABRS due to increasing beta-lactamase-producing organisms. CT sinus should NOT be obtained for uncomplicated ARS; it is reserved for complications, recurrent disease, or surgical planning. Incidental mucosal thickening on CT is extremely common (up to 40% of asymptomatic patients) and should not drive treatment. High-volume saline irrigation is the single most important adjunctive therapy in both ARS and CRS. Lund-Mackay score does not correlate well with symptom severity but is useful for documenting disease extent for surgical planning. Pott puffy tumor (frontal subperiosteal abscess) classically presents with forehead swelling and is most common in adolescents.

## References
- Rosenfeld RM, Piccirillo JF, Chandrasekhar SS, et al. "Clinical Practice Guideline (Update): Adult Sinusitis." *Otolaryngol Head Neck Surg*. 2015;152(2 Suppl):S1-S39.
- Fokkens WJ, Lund VJ, Hopkins C, et al. "European Position Paper on Rhinosinusitis and Nasal Polyps 2020 (EPOS 2020)." *Rhinology*. 2020;58(Suppl S29):1-464.
- Chandler JR, Langenbrunner DJ, Stevens ER. "The pathogenesis of orbital complications in acute sinusitis." *Laryngoscope*. 1970;80(9):1414-1428.
- Lund VJ, Mackay IS. "Staging in rhinosinusitis." *Rhinology*. 1993;31(4):183-184.