Chronic Suppurative Otitis Media (CSOM)

Definition

Epidemiology & Risk Factors

• Most common in children under 2 years and in areas with limited healthcare access and low socioeconomic status
• Higher incidence in certain populations: Native Americans, Inuit, Native Australians, and Native New Zealanders (likely genetic predisposition)
• Risk factors include:
  • Multiple prior episodes of acute otitis media (AOM)
  • AOM in the first few months of life
  • Chronic secretory otitis media
  • Eustachian tube dysfunction
  • Poor nutrition and living conditions

Types / Classification

Pathophysiology

1. Negative middle ear pressure - tympanic membrane (TM) retraction
2. Chronic middle ear effusion (serous or purulent)
3. Bacterial infection - inflammatory mediators - mucosal edema and granulation tissue
4. Sub-mucosal gland formation converts mucosa to secretory type, perpetuating the effusion
5. Granulation tissue enzymes degrade the TM's collagen skeleton
6. Progressive TM weakening - retraction pockets - perforation
7. Deep retraction pockets set the stage for cholesteatoma formation

Microbiology

• Pseudomonas aeruginosa (most common in chronic cases)
• Staphylococcus aureus
• Streptococcus pneumoniae, H. influenzae, Moraxella catarrhalis (particularly if AOM-related)
• Anaerobes
• Fungi (Candida spp.) - candida grows in 10% of ears with purulent otorrhea, and in up to 35% of ears treated with topical ciprofloxacin for 3 weeks

Clinical Features

Symptoms

• Intermittent or continuous otorrhea - sometimes foul-smelling
• Hearing loss (conductive, sometimes sensorineural)
• Otalgia and headache are uncommon - if present, suspect intracranial complication or malignancy
• Vertigo - suspect labyrinthitis or fistula

Signs (on otomicroscopy)

• Tympanic membrane perforation (central in tubotympanic; marginal/attic in atticoantral type)
• Mucopurulent discharge - may obscure TM
• Granulation tissue, polyps in the EAC
• Evidence of scutal or ossicular erosion
• Cholesteatoma (pearly white debris, typically attic)

Audiological Assessment

• Mandatory full audiometric evaluation
• Conductive hearing loss is most common
• Conductive loss >30 dB suggests ossicular chain erosion
• Sensorineural hearing loss (SNHL) may also be present (5-33 dB range in studies) - document preoperatively
• Note: hearing can occasionally be preserved even with ossicular erosion if cholesteatoma transmits sound directly to the oval window

Complications

Management

Medical (First-line, without cholesteatoma)

1. Aural toilet (microsuction/cleaning) - removes debris and discharge, aids topical drug penetration
2. Topical antibiotics - fluoroquinolone ototopicals (e.g., ciprofloxacin/ofloxacin) are first-line and superior to systemic antibiotics per Cochrane review; safe for use in the middle ear
   • Avoid aminoglycoside ototopicals when possible (ototoxicity risk); reserve for cases where benefit outweighs risk
3. Aural toilet with acetic acid solution (1:1 white vinegar:distilled water) - clears debris and provides antisepsis
4. Systemic antibiotics - for severe cases, copious drainage impeding topical treatment, or suspected complications
5. Culture and sensitivity - guides antibiotic selection (especially for resistant organisms)
6. Dry-ear precautions

Surgical

• Cholesteatoma is present (near-absolute indication)
• Medical treatment fails repeatedly
• Symptoms suggestive of complications (vertigo, facial weakness, headache)
• Persistent TM perforation after resolution of active infection

1. Eradication of disease
2. Prevention of recurrence
3. Preservation or restoration of hearing

• Tympanoplasty (myringoplasty): TM repair; ear should ideally be dry 3-4 weeks before surgery; >90% success for TM perforation repair
• Mastoidectomy:
  • Canal wall-up (CWU): preserves posterior EAC; easier aftercare; risk of residual cholesteatoma
  • Canal wall-down (CWD): removes posterior EAC wall; better exposure; open cavity requires lifelong monitoring and debridement
• Ossiculoplasty: reconstruction of ossicular chain, may be staged

Recent Evidence (2025 Cochrane Reviews)

• Topical antibiotics for CSOM (PMID 40484407) - confirms topical antibiotics as first-line
• Antibiotics vs. topical antiseptics for CSOM (PMID 40484400) - compares modalities
• Systemic antibiotics for CSOM (PMID 40484405) - reviews role of oral/IV antibiotics

Summary Points

• CSOM = TM perforation + chronic mucopurulent otorrhea (>2-6 weeks)
• Two types: tubotympanic (safe) vs. atticoantral (unsafe/cholesteatoma risk)
• Pathogenesis hinges on ET dysfunction + bacterial biofilms
• Main bugs: Pseudomonas aeruginosa, S. aureus, anaerobes
• First-line treatment: aural toilet + topical fluoroquinolone
• Surgery for cholesteatoma, failed medical treatment, or complications
• Audiometry is mandatory in all patients