Acute & Chronic Rhinosinusitis

Rhinosinusitis is symptomatic inflammation of the nasal mucosa and the paranasal sinuses — because the nose and sinuses share a continuous mucosal lining, isolated "sinusitis" is a misnomer and the EPOS guideline mandates the combined term. This topic is a perennial NEET PG favourite: expect questions on the commonest sinus involved, the pathogenesis of ostial obstruction, the bacteriology, the investigation of choice, and the dreaded orbital/intracranial complications.

Definition & classification

Rhinosinusitis = inflammation of the nose and paranasal sinuses characterised by two or more symptoms, one of which must be nasal blockage/obstruction/congestion OR nasal discharge (anterior/posterior drip), ± facial pain/pressure, ± reduction or loss of smell.

Classification is essentially by duration:

Type	Duration	Key feature
Acute rhinosinusitis (ARS)	< 4 weeks (complete resolution)	Mostly viral; bacterial in 0.5–2%
Subacute	4–12 weeks	Transitional
Chronic rhinosinusitis (CRS)	≥ 12 weeks (with persistent symptoms)	EPOS-defined; objective evidence needed
Recurrent acute	≥ 4 episodes/year, each resolving fully	Symptom-free between episodes

Acute bacterial rhinosinusitis (ABRS) is further suspected when there is the classic "double-sickening" pattern (initial viral URTI improves, then worsens), symptoms persisting > 10 days without improvement, or severe symptoms (high fever ≥ 39 °C with purulent discharge) for 3–4 consecutive days.

CRS is subdivided clinically and on endoscopy/CT into:

• CRS with nasal polyps (CRSwNP) — bilateral polyps in middle meatus; often eosinophilic; linked with asthma and aspirin sensitivity.
• CRS without nasal polyps (CRSsNP) — predominantly neutrophilic.

High-yield: The maxillary sinus is the most commonly involved sinus in both acute and chronic rhinosinusitis. Reason — its ostium lies high on the medial wall (anti-gravity drainage) and it is the largest sinus.

Anatomy you must know — the osteomeatal complex (OMC)

The OMC (or ostiomeatal unit) is the final common drainage pathway and is the single most important anatomical concept here. It includes the:

• Maxillary sinus ostium
• Infundibulum
• Hiatus semilunaris
• Ethmoid bulla
• Uncinate process
• Middle meatus

Anterior ethmoid, frontal and maxillary sinuses all drain into the middle meatus via the OMC. The posterior ethmoids drain into the superior meatus, and the sphenoid into the sphenoethmoidal recess. The nasolacrimal duct drains into the inferior meatus (not a sinus — common trick option).

High-yield: Obstruction of the OMC is the central event in the pathogenesis of sinusitis. FESS aims to restore ventilation/drainage of this complex rather than stripping sinus mucosa.

Etiology & pathophysiology

The pathophysiology follows a logical chain. Memorise it as a flow:

Mucosal oedema / ostial obstruction → impaired sinus ventilation & mucociliary clearance → mucus stasis & hypoxia → fall in intrasinus O₂, rise in CO₂ → ciliary dysfunction + favourable medium for bacteria → secondary bacterial infection → purulent sinusitis.

The three pillars maintaining sinus health are: (1) patent ostia, (2) functioning ciliary apparatus, (3) normal quality/quantity of secretions. Disruption of any one initiates the cycle.

Predisposing / contributory factors

• Local: deviated nasal septum, hypertrophied turbinates, nasal polyps, concha bullosa, foreign body, adenoid hypertrophy (children), dental infection (odontogenic maxillary sinusitis from premolar/molar root apices).
• General: viral URTI (most common precipitant), allergic rhinitis, swimming/diving, barotrauma, smoking.
• Systemic / immune & ciliary: cystic fibrosis, primary ciliary dyskinesia (Kartagener syndrome), immunodeficiency, Samter's triad (asthma + nasal polyps + aspirin sensitivity / aspirin-exacerbated respiratory disease, AERD).

Microbiology

Setting	Common organisms
Acute viral	Rhinovirus, influenza, parainfluenza, adenovirus
Acute bacterial (ABRS)	Streptococcus pneumoniae, Haemophilus influenzae (commonest two), Moraxella catarrhalis (esp. children)
Chronic	Staph aureus, anaerobes (Bacteroides, Peptostreptococcus), Gram-negatives (Pseudomonas), polymicrobial; biofilms important
Odontogenic	Anaerobes — foul-smelling discharge
Nosocomial / immunocompromised	Pseudomonas, Gram-negatives
Fungal (invasive, diabetic/neutropenic)	Mucor / Rhizopus (mucormycosis), Aspergillus

High-yield: In acute bacterial sinusitis the two leading pathogens are S. pneumoniae and H. influenzae. Mnemonic for ABRS triad of suspicion — "Persistence, Worsening, Severity" (> 10 days; double-sickening; severe ≥ 3–4 days).

Clinical features

Acute rhinosinusitis

• Facial pain/pressure/fullness over the affected sinus, worse on bending forward.
• Nasal obstruction and purulent (mucopurulent) anterior or postnasal discharge.
• Hyposmia/anosmia.
• Fever, malaise, headache.
• Site-specific pain: maxillary → cheek/upper teeth; frontal → forehead (classically periodic, worse mid-morning = "office headache" / "vacuum headache"); ethmoid → between/behind eyes, retro-orbital; sphenoid → vertex/occiput, deep-seated, referred to mastoid.

Chronic rhinosinusitis — the same symptoms but persistent ≥ 12 weeks, often less dramatic: nasal blockage, thick postnasal drip, hyposmia, facial heaviness, chronic cough, halitosis, recurrent acute exacerbations.

High-yield: Frontal sinusitis headache is classically periodic / diurnal — absent on waking, rising to a peak by midday and easing by evening (linked to ostial drainage with posture). Pott's puffy tumour is its danger sign.

Diagnosis & investigation of choice

Acute rhinosinusitis is largely a clinical diagnosis — imaging is NOT routinely required for uncomplicated ARS. Investigations come in for chronic disease, complications, treatment failure, or pre-surgical planning.

Diagnostic approach (EPOS framework)

EPOS (European Position Paper on Rhinosinusitis and Nasal Polyps) requires, for CRS in adults, presence ≥ 12 weeks of:

• Two or more symptoms, one of which must be nasal blockage/obstruction/congestion OR nasal discharge (anterior/posterior nasal drip); ± facial pain/pressure; ± reduction/loss of smell.

PLUS objective confirmation by either:

• Endoscopic signs — nasal polyps, and/or mucopurulent discharge primarily from the middle meatus, and/or oedema/mucosal obstruction primarily in the middle meatus; OR
• CT changes — mucosal changes within the OMC and/or sinuses.

High-yield: EPOS demands subjective symptoms PLUS objective evidence (endoscopy or CT) to label CRS. Symptoms alone are insufficient.

Imaging

Modality	Role
X-ray Waters view (occipitomental)	Best plain film for maxillary sinus; shows mucosal thickening, opacity, air–fluid level. Largely historical now.
Caldwell view (occipitofrontal)	Frontal & ethmoid sinuses
Lateral view	Sphenoid sinus, adenoids
Submentovertical (basal) view	Sphenoid, posterior ethmoids
CT paranasal sinuses (coronal, non-contrast)	Investigation of choice for CRS and gold standard for pre-FESS mapping; defines OMC anatomy & bony landmarks
Contrast CT / MRI	When complications suspected (orbital, intracranial); MRI superior for soft-tissue/intracranial and fungal extension

High-yield: CT coronal sections of the PNS is the investigation of choice for chronic rhinosinusitis and is mandatory before FESS (acts as the surgeon's "road map," assesses Keros classification of cribriform plate depth, Onodi/Haller cells). Plain X-ray Waters view is the classic plain film for the maxillary sinus showing an air–fluid level.

Additional: nasal endoscopy (diagnostic mainstay for direct visualisation), nasal/sinus swab culture (guided endoscopic culture from middle meatus preferred over blind nasal swab), allergy testing, and sweat chloride/ciliary studies in recurrent paediatric disease.

Management & drug of choice

Acute viral rhinosinusitis

Self-limiting → symptomatic treatment: analgesics (paracetamol), nasal saline irrigation, topical/oral decongestants (short course, < 5–7 days to avoid rhinitis medicamentosa), steam inhalation, intranasal corticosteroids. No antibiotics.

Acute bacterial rhinosinusitis (ABRS)

Antibiotics indicated only when bacterial criteria met (> 10 days, double-sickening, or severe).

Drug of choice → Amoxicillin–clavulanate (preferred over plain amoxicillin given beta-lactamase–producing H. influenzae/M. catarrhalis).

• Penicillin allergy: doxycycline, or respiratory fluoroquinolone (levofloxacin/moxifloxacin), or a macrolide.
• Duration typically 5–10 days.
• Adjuncts: intranasal corticosteroids (reduce mucosal oedema), saline irrigation, analgesia.

Chronic rhinosinusitis

Medical therapy first, often prolonged:

1. Intranasal corticosteroids — mainstay for both CRSwNP and CRSsNP.
2. Saline (high-volume) nasal irrigation — strong evidence.
3. Short course of oral corticosteroids — useful in CRSwNP / severe polyps.
4. Prolonged low-dose macrolides (e.g. clarithromycin) — anti-inflammatory role, especially in CRSsNP with normal IgE.
5. Treat underlying allergy (antihistamines, leukotriene antagonists), GERD, and dental focus.
6. Biologics (dupilumab — anti-IL-4/IL-13) for severe refractory CRSwNP.

Surgery — FESS (Functional Endoscopic Sinus Surgery)

Indicated when maximal medical therapy fails, or for complications/anatomical obstruction.

High-yield — FESS indications: failure of maximal medical therapy in CRS, nasal polyposis, recurrent acute rhinosinusitis, mucocele/mucopyocele, fungal sinusitis, complications (e.g. orbital abscess), CSF rhinorrhoea repair, and to obtain biopsy/clear obstruction of the OMC. The principle of FESS is restoring ventilation and natural mucociliary drainage of the OMC, preserving mucosa — NOT radical mucosal stripping (which was the old Caldwell-Luc philosophy).

Stepwise treatment flow (ABRS):

1. Confirm bacterial criteria (>10 d / worsening / severe).
2. Start amoxicillin–clavulanate + intranasal steroid + saline.
3. Reassess at 48–72 h → if no improvement, switch antibiotic / consider resistance.
4. No response or red-flag signs → imaging (CT) + ENT referral to exclude complication.

Complications

These are the most examined part of this topic. Complications arise chiefly from ethmoid (orbital, thinnest lamina papyracea) and frontal (intracranial, Pott's) sinusitis.

Orbital complications — Chandler classification (commit this):

Stage	Chandler classification
I	Preseptal cellulitis (inflammatory oedema)
II	Orbital (postseptal) cellulitis
III	Subperiosteal abscess
IV	Orbital abscess
V	Cavernous sinus thrombosis

High-yield: Ethmoid sinusitis is the commonest source of orbital complications (spread through the paper-thin lamina papyracea). Proptosis, chemosis, restricted eye movement (ophthalmoplegia), and decreasing visual acuity signal an orbital/subperiosteal abscess — a surgical emergency requiring contrast CT and urgent drainage.

Bony / local

• Mucocele / mucopyocele (commonest in frontal sinus) — slowly expanding, can cause proptosis.
• Osteomyelitis of maxilla (infants) or frontal bone.

Frontal sinusitis → osteomyelitis of frontal bone with subperiosteal abscess = Pott's puffy tumour — a doughy, tender, fluctuant forehead swelling.

High-yield: Pott's puffy tumour = subperiosteal abscess + osteomyelitis of the frontal bone, classically from frontal sinusitis (or trauma), often in adolescents. It is a marker of possible intracranial spread — get contrast CT/MRI.

Intracranial (mostly from frontal & sphenoid/ethmoid sinuses): meningitis (commonest intracranial complication overall), epidural abscess, subdural empyema, brain abscess (frontal lobe), cavernous sinus thrombosis (from sphenoid/ethmoid; cranial nerves III, IV, V₁–V₂, VI involvement, the only structures within the sinus include CN VI and the internal carotid artery).

Descending / distant: acute otitis media, pharyngitis, laryngitis, bronchitis (sinobronchial syndrome), exacerbation of asthma.

Special — fungal sinusitis spectrum

• Acute invasive (fulminant) — mucormycosis in uncontrolled diabetics/DKA & neutropenic patients: rapidly progressive, black necrotic eschar over palate/turbinate, requires urgent surgical debridement + IV liposomal amphotericin B + control of underlying disease.
• Chronic invasive, granulomatous, fungal ball (mycetoma — typically maxillary), and allergic fungal rhinosinusitis (AFRS) — type I/III hypersensitivity, eosinophilic mucin, high IgE, "double-density" on CT.

High-yield: A diabetic in ketoacidosis with facial pain, orbital swelling and a black eschar → suspect rhino-orbito-cerebral mucormycosis until proven otherwise. KOH mount shows broad aseptate, right-angle branching hyphae.

Key differentials

Condition	Distinguishing clue
Allergic rhinitis	Sneezing, watery rhinorrhoea, itching, pale boggy turbinates, seasonal/allergen-linked, eosinophils; no purulence
Migraine / tension headache	No nasal symptoms; photophobia/aura; normal endoscopy
Trigeminal neuralgia	Lancinating, trigger zones; not positional with bending
Dental (odontogenic) pain	Localised to tooth; unilateral foul maxillary discharge
Nasopharyngeal / sinonasal malignancy	Unilateral blood-stained discharge, mass, cranial nerve signs, unilateral persistent obstruction — red flag, biopsy
Granulomatosis with polyangiitis (Wegener)	Crusting, septal perforation, saddle nose, c-ANCA positive
Wegener / sarcoid / NK-T lymphoma	"Midline destructive" picture — image & biopsy
CSF rhinorrhoea	Unilateral clear watery discharge; beta-2 transferrin positive

High-yield: Unilateral nasal symptoms (especially blood-stained discharge or a single polyp/mass) demand exclusion of malignancy and warrant biopsy + imaging — never dismiss as simple sinusitis.

Recently asked / exam angle

• Most common sinus involved in sinusitis → maxillary. (Repeatedly asked.)
• First sinus to develop / pneumatised at birth → maxillary and ethmoid (frontal and sphenoid develop later; frontal not present at birth, develops ~age 5–6 and visible on X-ray by 6).
• Commonest sinus to cause orbital complications → ethmoid (via lamina papyracea); commonest to cause intracranial complications → frontal.
• Pott's puffy tumour → frontal bone osteomyelitis + subperiosteal abscess.
• Investigation of choice for CRS / pre-FESS → coronal CT PNS. Plain film for maxillary sinus → Waters (occipitomental) view showing air–fluid level.
• Drug of choice in ABRS → amoxicillin–clavulanate.
• EPOS criteria — symptom duration cut-offs (acute < 12 weeks, chronic ≥ 12 weeks) and the need for objective endoscopy/CT evidence.
• Samter's / Aspirin triad → asthma + nasal polyps + aspirin sensitivity.
• Mucormycosis → diabetic ketoacidosis, black eschar, aseptate right-angle hyphae, amphotericin B + debridement.
• OMC → central to pathogenesis and the target of FESS.
• Structures in cavernous sinus / sphenoid sinusitis complication — CN VI most medial and first affected.
• Haller cell (infraorbital ethmoid cell) and concha bullosa as anatomical causes of recurrent maxillary sinusitis on CT — increasingly asked.

Rapid revision

1. Rhinosinusitis — nose + sinus inflammation; "sinusitis" alone is a misnomer (EPOS term).
2. Maxillary sinus = most commonly involved (high ostium → anti-gravity drainage).
3. OMC obstruction = central pathogenic event; FESS restores its drainage, preserves mucosa.
4. Acute < 12 wk, chronic ≥ 12 wk; CRS needs symptoms + objective (endoscopy/CT) evidence.
5. ABRS suspected by >10 days, double-sickening, or severe symptoms; commonest bugs S. pneumoniae & H. influenzae.
6. Drug of choice ABRS → amoxicillin–clavulanate; CRS mainstay → intranasal steroids + saline irrigation.
7. CT coronal PNS = IOC for chronic disease & pre-FESS; Waters view shows maxillary air–fluid level.
8. Ethmoid → orbital complications (lamina papyracea); Chandler classification stages them (I preseptal → V cavernous sinus thrombosis).
9. Pott's puffy tumour = frontal bone osteomyelitis + subperiosteal abscess; warns of intracranial spread.
10. Frontal sinusitis headache = periodic/diurnal (peaks midday).
11. Mucormycosis in DKA/neutropenia → black eschar, aseptate right-angle hyphae, amphotericin B + urgent debridement.
12. Unilateral blood-stained discharge or single mass → exclude malignancy (biopsy + imaging), don't treat as plain sinusitis.