Rhinosinusitis and rhinitis

Definition and Classification

• Chronic rhinosinusitis (CRS) is symptomatic mucosal inflammation of the nose and paranasal sinuses persisting for 12 weeks or longer, confirmed by objective findings on nasal endoscopy or imaging.
• It is one of the most prevalent chronic conditions managed in otolaryngology practice and a leading cause of antibiotic prescription and quality-of-life impairment.

Diagnostic Criteria

At least two of the following four cardinal symptoms must be present:

• Nasal obstruction or blockage
• Nasal discharge (anterior or posterior, which may be purulent)
• Facial pain, pressure, or fullness
• Reduction or loss of sense of smell (hyposmia or anosmia)

And at least one objective confirmatory finding:

• Endoscopic evidence: purulent mucus in the middle meatus or ethmoid region, mucosal oedema, or nasal polyps
• CT evidence: mucosal thickening, sinus opacification, or bony remodelling

Phenotypic Classification

Recurrent Acute vs Chronic

Patients with recurrent acute bacterial rhinosinusitis (RABS; ≥4 episodes/year) are normal between episodes and should be distinguished from CRS patients, who have persistent baseline symptoms and objective sinonasal abnormality.

Pathophysiology

CRSsNP

• Predominantly driven by Th1 lymphocytes and innate immune activation
• Neutrophil-dominant infiltrate with IFN-$\gamma$ and IL-8 upregulation
• Disrupted mucociliary clearance promotes bacterial colonisation and biofilm formation
• Anatomical factors (e.g. septal deviation, concha bullosa, agger nasi hypertrophy) may perpetuate ostial obstruction

CRSwNP

• Type 2 inflammatory cascade driven by TSLP, IL-25, and IL-33 released from damaged sinonasal epithelium (epithelial alarmins)
• IL-5-driven eosinophil recruitment and survival; IgE synthesis via IL-4 and IL-13
• Polyps arise as oedematous prolapsed mucosa with eosinophilic stroma, originating most often in the ethmoid clefts and middle meatus
• Arachidonic acid metabolism dysregulation in AERD leads to leukotriene overproduction and prostaglandin E2 deficiency, causing mast cell activation on NSAID exposure

Final Common Pathway

• Regardless of subtype, the osteomeatal complex (OMC) is the central anatomical bottleneck.
• Obstruction of the OMC impairs drainage of the maxillary, anterior ethmoid, and frontal sinuses, creating a microenvironment permissive to chronic infection and mucosal inflammation.
• Mucociliary clearance failure, biofilm formation, and microbial dysbiosis perpetuate this cycle.

Clinical Assessment

History

• Duration, severity, and pattern of cardinal symptoms
• Impact on quality of life (validated tools: SNOT-22 is standard)
• Identify comorbidities: asthma (unified airway), allergic rhinitis, AERD, immunodeficiency (recurrent sinusitis in multiple anatomical sites warrants investigation), cystic fibrosis, primary ciliary dyskinesia
• Drug history: aspirin/NSAIDs, topical decongestant overuse (rhinitis medicamentosa)
• Smoking and occupational exposures
• Previous sinus surgery: scarring, synechiae, lateralised middle turbinate

Examination

• Anterior rhinoscopy: mucosal oedema, secretions, septal deviation, polyps visible in anterior nasal cavity
• Nasal endoscopy (0° or 30° rigid endoscope, or flexible scope): essential for confirming diagnosis
  • Assess middle meatus for polyps, purulent mucus, mucosal oedema
  • Assess olfactory cleft in polyp cases
  • Document Lund-Kennedy endoscopy score at baseline and post-treatment
• Systemic examination: chest (wheeze/prolonged expiration), skin (aspirin sensitivity, urticaria)

Endoscopic Staging of Polyps

Investigation

Imaging

• CT paranasal sinuses (non-contrast axial + coronal reconstruction): gold standard for surgical planning
  • Assess extent of disease: Lund-Mackay CT scoring system (0-2 per sinus/OMC; maximum 24)
  • Identify anatomical variants: Onodi cells (risk to optic nerve), Haller cells (infraorbital ethmoid cells obstructing OMC), dehiscent lamina papyracea or carotid canal, low-lying skull base
  • Note: CT is not the positive gold standard as asymptomatic mucosal thickening is common; correlation with clinical findings is mandatory
• MRI: reserved for suspected complications, orbital or intracranial extension, or when differentiating inflammatory from neoplastic disease (soft tissue characterisation)

Allergy and Immunology

• Skin prick testing or specific IgE for inhalant allergens (particularly relevant for CRSwNP with concurrent allergic rhinitis)
• Total IgE and eosinophil count (markers of type 2 disease; relevant to biologic eligibility)
• Immunoglobulin levels (IgG, IgA, IgM) if recurrent/refractory disease suggests humoral immunodeficiency
• Aspirin challenge or NSAID history to identify AERD

Mucociliary Function

• Saccharin transit time (screening for ciliary dysfunction)
• Nasal nitric oxide: markedly reduced in primary ciliary dyskinesia (PCD)
• Electron microscopy or high-speed video analysis of ciliary ultrastructure if PCD suspected

Microbiology

• Endoscopically directed middle meatal swabs are the standard method for non-invasive culture; diagnostic yield is superior to blind nasal swabs
• Sinus aspirate at time of surgery provides most reliable culture
• Common organisms: Staphylococcus aureus (dominant in CRSwNP), Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis; MRSA increasingly isolated
• Pseudomonas aeruginosa in post-surgical, cystic fibrosis, or immunocompromised patients

Medical Management

Stepwise Framework

• Medical therapy is the foundation of CRS management.
• Surgery is indicated when adequate medical therapy fails.

First-line and maintenance:

1. Intranasal corticosteroids (INCS): core therapy for all subtypes; reduces mucosal oedema and polyp burden; demonstrated efficacy on obstruction, discharge, and olfaction; multiple delivery methods (spray, drop [head-down-forward position for polyp disease], high-volume irrigation post-surgery)
2. Saline nasal irrigation: large-volume isotonic or hypertonic saline (e.g. 240 mL rinse) improves mucociliary clearance, reduces mucosal oedema, and enhances drug delivery; superior to spray for drug penetration post-operatively
3. Allergen avoidance and immunotherapy where allergy drives disease

Short-course systemic corticosteroids (CRSwNP):

• Prednisolone oral course (typically 25-50 mg/day, 5-14 days): rapid reduction in polyp bulk; used pre-operatively to improve surgical field, reduce intraoperative bleeding, and confirm steroid responsiveness
• Perioperative systemic steroids (pre- and short post-operative course) reduce intraoperative bleeding and early recurrence

Antibiotics:

• Acute exacerbations: guided by culture where possible; amoxicillin-clavulanate standard empirical choice for ABRS
• Long-term low-dose macrolides (e.g. roxithromycin 150 mg daily for 12 weeks): anti-inflammatory and immunomodulatory properties; evidence in CRSsNP and CRSwNP without marked eosinophilia; benefit in biofilm disruption
• Topical antibiotics (e.g. mupirocin irrigation for MRSA biofilm): evidence emerging

Leukotriene receptor antagonists: adjunct in AERD and CRSwNP with asthma

Biologic Therapies (CRSwNP)

• Indicated for severe CRSwNP inadequately controlled despite maximal medical therapy and ESS.
• Eligibility criteria are defined by national criteria and include bilateral polyp disease, significant symptom burden, and criteria for type 2 inflammation (elevated total IgE, blood or tissue eosinophilia, comorbid asthma/AERD).

• Biologics do not replace surgery but can serve as a bridge, alternative, or post-surgical adjunct.
• Duration of therapy and criteria for cessation are evolving.

Surgical Management: Functional Endoscopic Sinus Surgery (FESS)

Indications

• CRS with objective disease refractory to adequate medical therapy
• Anatomical obstruction not amenable to medical treatment
• CRS with orbital or intracranial complications (semi-urgent/urgent)
• Fungal rhinosinusitis (allergic or invasive)
• Mucocele causing orbital or intracranial pressure
• Sinonasal neoplasm (diagnostic or therapeutic)
• No consensus exists on the minimum duration of "adequate" medical therapy, but most guidelines recommend at least 12 weeks of appropriately delivered INCS and saline irrigation before surgery is considered.
• Evidence suggests earlier surgery in patients with established disease may improve quality-of-life outcomes compared with prolonged deferral.

Goals of FESS

• Remove obstructing tissue around natural sinus ostia to restore ventilation and drainage
• Eliminate irreversibly diseased mucosa and infected bone while preserving functional mucosa
• Create a surgically accessible sinus cavity that allows topical drug delivery and surveillance endoscopy
• FESS is not curative for CRS; it optimises the environment for ongoing medical therapy

Preoperative Preparation

• CT planning: reviewed on the day of surgery; identify high-risk anatomy (low skull base, Onodi cells, dehiscent carotid/optic nerve, asymmetric skull base)
• Optimise medical therapy preoperatively: systemic steroids in CRSwNP to reduce vascularity and improve visualisation
• Counsel on risks, realistic expectations, and the need for lifelong medical maintenance and surveillance
• Consent for: bleeding, infection, orbital injury (diplopia, blindness), skull base violation (CSF leak, meningitis, intracranial injury), anosmia, dental/lacrimal injury, failure and recurrence

Key Surgical Steps and Anatomy

Osteomeatal Complex anatomy (the surgical target):

• The OMC is the functional drainage unit of the anterior sinuses (maxillary, anterior ethmoid, frontal) and is situated in the middle meatus
• Bounded medially by the middle turbinate, laterally by the lamina papyracea, superiorly by the anterior skull base
• Components: uncinate process, infundibulum, hiatus semilunaris, ethmoidal bulla, and natural maxillary ostium

Standard FESS sequence (anterior-to-posterior, medial-to-lateral):

1. Uncinectomy: removal of the uncinate process; the key initial step that exposes the infundibulum and natural maxillary ostium; the medial orbital wall (lamina papyracea) is the lateral boundary; risk: entry into orbit if uncinectomy directed too laterally
2. Maxillary antrostomy: enlargement of the natural ostium posteroinferiorly into the posterior fontanelle; the nasolacrimal duct is at risk anteriorly; do not create a counter-opening in the posterior fontanelle separate from the natural ostium (failure of mucociliary recirculation)
3. Anterior ethmoidectomy: systematic removal of anterior ethmoid air cells; the ground lamella (basal lamella of the middle turbinate) separates anterior from posterior ethmoid; skull base risk: anterior ethmoid artery marks the anterior skull base; dehiscence or variation in skull base height increases perforation risk
4. Posterior ethmoidectomy: removal of posterior ethmoid cells posterior to the ground lamella; the sphenoid face is the posterior boundary; optic nerve risk: Onodi cells (sphetoethmoid cells) contain the optic nerve in their lateral wall
5. Sphenoidotomy: opening of the sphenoid face inferomedially, enlarging the natural ostium; the optic nerve, internal carotid artery, and cavernous sinus are in the lateral sphenoid wall and are at risk with aggressive lateral dissection
6. Frontal sinusotomy (Draf I/IIa/IIb/III): the frontal recess is the most technically demanding region; bounded anteriorly by the agger nasi cell, posteriorly by the ethmoid roof and skull base, medially by the middle turbinate, laterally by the lamina papyracea; Draf III (modified Lothrop) creates a common frontal drainage tract in refractory frontal disease

Powered Instrumentation

• Microdebrider (oscillating shaver): precise soft-tissue removal while preserving mucosa; reduces bleeding
• Image guidance (electromagnetic or CT-based intraoperative navigation): useful in revision surgery, obliterated landmarks, or high-risk anatomy; does not replace anatomical knowledge or eliminate risk

Balloon Sinus Dilation

• Office-based or intraoperative adjunct for CRSsNP without significant polyposis
• Dilates ostia without mucosal removal; preserves mucosa and bone
• Best evidence in frontal, maxillary, and sphenoid ostia in RABS and mild-moderate CRSsNP
• Not appropriate for CRSwNP requiring polyp removal or significant ethmoidectomy

Postoperative Care

• Debridement and surveillance endoscopy: critical for success; weekly for 4-6 weeks post-operatively; removes crusting, fibrin, and early synechiae under local anaesthetic in clinic
• Topical therapy resumption: INCS irrigation (e.g. budesonide 1 mg in 240 mL saline) commenced from week 1-2 post-operatively; high-volume delivery to the post-surgical cavity is significantly more effective than sprays
• Systemic corticosteroids: short post-operative course (5-10 days prednisolone) in CRSwNP reduces early mucosal recurrence and re-polyposis
• Long-term maintenance: INCS and saline irrigation indefinitely; re-institute systemic steroids for acute exacerbation or polyp recurrence; consider macrolides in non-eosinophilic subtype
• Biologic commencement or continuation post-FESS in eligible severe CRSwNP

Complications of FESS

Intraoperative

Postoperative

• Synechiae and adhesion formation: between middle turbinate and lateral wall; prevented by careful mucosal preservation and early debridement
• Middle turbinate lateralisation: obstructs surgical cavity; prevention by middle turbinate suture or partial resection
• Frontal recess stenosis: most common cause of frontal sinusitis failure post-FESS; requires revision Draf IIb/III
• Anosmia: injury to olfactory mucosa in the olfactory cleft; a recognized consent item
• Recurrence of polyps: universal in severe phenotypes; managed with escalated medical therapy and revision FESS if indicated
• Empty nose syndrome: rare, following overly aggressive inferior turbinectomy; paradoxical nasal obstruction with patent airway; difficult to treat

Causes of FESS Failure

Systematic analysis before revision surgery:

1. Residual or inadequately addressed disease: retained ethmoid partitions, missed cells (particularly frontal recess cells), incomplete uncinectomy
2. Inadequate post-operative medical therapy: failure to maintain INCS, saline irrigation, or address allergy
3. Anatomical failure: synechiae, lateralised middle turbinate, neo-ostium separate from natural ostium (mucociliary recirculation failure)
4. Refractory underlying disease: severe AERD, uncontrolled asthma, aspirin sensitivity, immunodeficiency, PCD, or fungal disease
5. Mucosal biofilm: methicillin-resistant S. aureus, Pseudomonas; consider topical antibiotics and culture-directed therapy

Special Populations and Considerations

Asthma and AERD

• Aspirin desensitisation following ESS reduces polyp recurrence rate and systemic asthma events; requires specialist input
• Asthma optimisation pre-operatively is essential; severe asthma is a risk factor for general anaesthesia

Immunodeficiency

• IgG subclass deficiency, common variable immunodeficiency, and specific antibody deficiency cause recurrent sinusitis; immunoglobulin replacement therapy may reduce surgical frequency
• HIV, haematological malignancy, and transplant patients have higher risk of fungal rhinosinusitis

Fungal Rhinosinusitis

• Allergic fungal rhinosinusitis (AFS): type 1 hypersensitivity to fungi; thick "peanut butter" eosinophilic mucin; characteristically unilateral with heterogeneous CT density; elevated total IgE and fungal-specific IgE; surgical clearance plus prolonged INCS; consider immunotherapy
• Invasive fungal sinusitis: life-threatening; immunocompromised host; Aspergillus or mucormycosis; black necrotic mucosa on endoscopy; urgent surgical debridement plus systemic antifungal therapy; high mortality

Cystic Fibrosis

• CRS universal in CF; Pseudomonas and S. aureus colonisation; FESS primarily to reduce lower airway bacterial burden
• Modified surgical approach: address nasal polyps but avoid aggressive turbinate surgery

Paediatric CRS

• Less common than in adults; exclude adenoid hypertrophy (often first-line adenoidectomy)
• CT radiation concerns: limit use; treat medically longer before surgical commitment
• FESS technique modified: conservative uncinectomy and antrostomy; avoid skull base and frontal recess dissection in young children due to immature anatomy

Prognostic Factors and Outcome Measurement

• SNOT-22 (Sino-Nasal Outcome Test): 22-item validated patient-reported outcome; domain scores for nasal, ear/facial, sleep, and psychological; the standard outcome measure for research and clinical audit
• Lund-Kennedy endoscopy score and Lund-Mackay CT score: objective measures for disease severity and surgical planning
• Factors associated with poorer surgical outcome: asthma, AERD, higher pre-operative CT scores, smoking, immunodeficiency, revision surgery, inadequate post-operative care
• ESS provides durable improvement in quality of life in most patients; long-term results require maintained medical therapy and endoscopic surveillance