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Sinusitis: Causes, Types of Sinusitis, Diagnosis, Treatment

Jul 24, 2023

Sinusitis: Causes, Types of Sinusitis, Diagnosis, Treatment

Inflammation or swelling of the tissue lining your sinuses is known as sinusitis. Structures inside your face called sinuses are usually air-filled. Allergies, viral infections, and bacterial infections can aggravate them to the point where they become clogged and fluid-filled. In addition to other symptoms including a stuffy nose and facial pain and pressure, this can also induce nasal congestion. Another name for sinusitis is rhinosinusitis.

Etiology of Acute Sinusitis

  • Nasal Infection: Most acute sinusitis start as viral infections followed by bacterial invasion
  • Swimming and diving
  • Trauma
  • Dental infection- Predisposing factors for maxillary sinus can be due to dental infection. Maxillary sinus is related to the 2nd premolar and 1st molar.

Causes of Acute Sinusitis

All the sinus have their own drainage pathway or drainage ostia. If there is obstruction to the ventilation of the sinuses due to edema, mucus, polyps, URTI hence there will be inflammation of all the mucosal lining of sinuses. These inflammation of mucosal cells produce exudate which can be sterile or infected.  If sinus is infected it is known as Suppurative sinusitis. If non-infected known as Sterile sinusitis. Majority of cases, bacterial infection occurs. Most common bacteria for causing acute sinusitis: S.pneumoniae. Sinusitis of dental origin, the bacteria affected is Mixed infection (aerobic and anaerobic infection).

Predisposing Factors of Acute Sinusitis

  • Obstruction to sinus ventilation and drainage
  • Stasis of secretion in nasal cavity (cystic fibrosis) - Ciliary motility defect predispose to mostly chronic sinus infection
  • Allergy- Mucosal edema will obstruct the ventilation of sinuses causing retention of secretion and infection resulting in sinusitis

Systemic factors

  • Attack of exanthematous fever (measles, chicken pox, whooping cough)
  • Nutritional deficiencies
  • Immune deficiencies


Bacteria such as Streptococcus pneumoniae, H.influenza, Moraxella, Streptococcus pyogenes, Staphylococcus aureus results in acute sinusitis, Anaerobic organisms and mixed infections are seen in sinusitis of dental origin.

Sinusitis Secondary to Dental Infection        

  • Secondary to infections of roots of molar and 2nd premolar teeth
  • Causes maxillary sinusitis
  • Oroantral fistula following tooth extraction is a cause
    • Oroantral fistula is communication between maxillary sinus and oral cavity
  • Anaerobic organisms and mixed infections are seen in sinusitis of dental origin
  • Dental infections are very fulminating and result in suppurative sinusitis

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Clinical features of Acute Sinusitis

Clinical features of Acute sinusitis
Major criteriaMinor criteria
Nasal obstruction
Facial pain or pressure
Purulent nasal dischargeCough 
Fever Halitosis 
Nasal congestionEar pain and pressure
Hyposmia or anosmiaDental pain
Facial congestion or fullnessNA

For diagnosis 2 major or 1 major and 2 minor symptoms are required:

For diagnosis 2 major or 1 major and 2 minor symptoms
Headache or painUsually seen over cheek and forehead and can be confused with frontal sinusitisLocalised to frontal sinuses above medial canthusLocalised over bridge of nose, medial and deep to the eyeOcciput or vertex
TendernessCheek (pressing over canine fossa)Over frontal sinus (pressing on the floor of frontal sinus)Bridge of noseNIL
Redness and edemaCheek, lower eyelid swellingUpper eyelid puffinessBoth eyelids become puffyNIL
Site of nasal dischargeMiddle meatusVertical streak of mucopus high up in anterior portion of middle meatusSeen in middle or superior meatus depending on involvement of anterior or posterior groupSeen in posterior rhinoscopy on the roof and posterior wall of nasopharynx
Early ComplicationsOrbital cellulitis, Osteomyelitis, Frontal sinusitisOrbital cellulitis, Osteomyelitis, intracranial abscessOrbital cellulitis, vision loss, cavernous sinus thrombosis, intracranial abscess
  • Pus in sphenoethmoidal recess leads to sphenoid sinusitis
  • Pus in superior meatus leads to posterior ethmoidal sinusitis
  • Pus in middle meatus leads to Frontal or Maxillary or Anterior ethmoidal sinusitis
Clinical features of Acute sinusitis

Maxillary Sinusitis    

Postural test is done to differentiate maxillary sinus from frontal and ethmoidal sinusitis. Clean the pus in the middle meatus and then put the patient in head lying (tilt) opposite side. If there is reappearance of pus, then it is identified as maxillary sinusitis. If no reappearance of pus, ask the patient to sit upright head hanging down position, gravity depended reappearance of sinus indicates Frontal sinusitis. If no reappearance on both positions, then it is called Ethmoidal sinusitis.

Frontal Sinusitis        

Pain has characteristic periodicity or Office headache  While sleeping, anti-gravity position will cause retention of secretion in frontal sinus, the sinus with full of pus while wake-up causes severe headache in morning. In sitting position throughout the day, there will be gravity depended drainage by evening sinus become little less accumulation with no headache. Tenderness on the floor of frontal sinus just above medial canthus. Edema of upper eyelid.

Ethmoidal Sinusitis               

Pain is located on the bridge of nose, deep to the eye, aggravated by movements of eyeball Orbital cellulitis

Sphenoidal Sinusitis        

Characteristic feature: Vertex headache or occipital headache and Post nasal discharge

Diagnosis of Acute Sinusitis

  • Clinical examination
  • Diagnostic nasal endoscopy
  • X-ray is the FIRST investigation to be done
  • CT scan in acute sinusitis is done only when a high risk complication is anticipated
  • Sinus Puncture and Bacterial Culture- Gold standard for Diagnosing Bacterial Sinus Infection
  • Accurate method of diagnosis is sinuscopy and biopsy

Treatment of Acute Sinusitis

  • Medical: Antibiotic TOC + decongestants + analgesics + hot fomentation
  • Surgical: If no response to medical therapy,If it’s progressing to complication or FESS (most preferred) /Ethmoidectomy/Trephination of frontal sinus

Chronic Sinusitis          

Failure of resolution of acute infection for more than 12 weeks . Maxillary sinus is most commonly involved. Symptoms include Purulent nasal discharge is the most common symptom with nasal obstruction. Syndromic causes and ciliary motility disorders suggestive of chronic sinusitis. Investigation of choice is Plain CT scan of nose and paranasal sinus


Medical therapy: Antibiotics with antral irrigation is tried


  •  Required for ventilating the sinuses
  •  Endoscopic sinus surgery
  •   Rarely open procedures like intranasal antrostomy or caldwell luc operation

Fungal Sinusitis

Fungal Sinusitis

AFRS (Allergic Fungal Rhino Sinusitis)

It is a non-invasive form Caused by Aspergillus. AFRS and Fungal ball does not cause erosion of bone

 We use Bent and Kuhn criteria for AFRS which includes:

  • Serum IgE level elevated
  • KOH stain Positive
  • Allergic mucin
  • Nasal polyposis
  • Double density
AFRS (Allergic Fungal Rhino Sinusitis)


This fungus enter into blood vessel and obstruct many blood vessels, no bloody supply causing tissue ischemia which leads to necrosis turning into Black eschar. Causative organism is  Angioinvasive fungus. It is  Rapidly progressive condition. Black turbinate sign is Seen on MRI (hallmark sign). Radiological IOC: MRI with contrast. Diagnosis is done by histopathology and culture. Treatment is done by  Liposomal Amphotericin B + Radical debridement.


Complications of Sinusitis 


  • Local: Limited to the sinuses.
  • Maxillary sinus: cystic transformation of mucosa known as Retention cyst. If there is obstruction to the sinus ostium, there will be accumulation of mucus in the sinus with epithelial lined sac around it known as Mucocoele. Mucocoele will gradually expands and cause thinning and destruction of the overlying bone. If mucocoele infected and forms Pyocoele. Infection of overlying bone known as Osteomyelitis
  • Orbital
    • Preseptal cellulitis
  • Cellulitis of skin and subcutaneous tissue: Orbital cellulitis
  • Subperiosteal abscess 
  • Orbital abscess
  • Cavernous sinus thrombosis
Complications of Sinusitis
  • Intracranial
    • Meningitis
    • Extradural abscess
    • Subdural abscess
    • Brain abscess
  • Descending infection
    • Adenoiditis
    • Tonsillitis
    • Pharyngitis
    • Laryngitis 
Complications of Sinusitis 
Local Mucocoele, pyocoele, retention cyst, osteomyelitis
Orbital Chandlers classification
Intracranial Meningitis, abscess
Descending infection Tonsillitis, Pharyngitis, Laryngitis, Tracheobronchitis

Osteomyelitis of the frontal bone causing subperiosteal abscess known as Pott’s puffy tumor. Orbital cellulitis is particularly common in ethmoid sinusitis.


It Most commonly involves frontal sinus, Least commonly involves sphenoid sinus. In Frontal sinus mucocoele the Site of infection is  superomedial quadrant of orbit. eye is displaced forward, downward, laterally. Cystic, non-tender, egg shell cracking swelling is present. X-ray shows  Loss of scalloped margins. Treatment is done by Frontoethmoidectomy to promote drainage of frontal sinus.


Cavernous Sinus Thrombosis

Infection of ethmoids or sphenoid sinuses is most common cause of cavernous sinus thrombosis,But infection can spread from nose, ear, throat, and orbit. Orbital cellulitis can secondarily lead to cavernous sinus thrombosis

Cavernous Sinus Thrombosis V/S Orbital Cellulitis

Cavernous Sinus Thrombosis V/S Orbital Cellulitis
Cavernous sinus thrombosisOrbital cellulitis
SourceNose, sinuses, orbit, ear or pharynxEthmoid sinuses
OnsetAbrupt with chills and rigorsSlow
Edema of eyelidsBilateral edema of eyelids, chemosis and proptosisUnilateral edema of eyelids, near the inner canthus leading to chemosis and proptosis
Cranial nerve involvementInvolves individually and sequentiallyInvolved concurrently with complete ophthalmoplegia


ConditionCranial nerves involvedCranial nerves not involved
Orbital apex syndromeII, III, IV ±V2
Superior orbital fissure syndromeIII, IV, VI±V2II
Cavernous sinus syndromeIII, IV, VIII, V2

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