Chronic Suppurative Otitis Media (CSOM)

Definition

Epidemiology

• Most common in children under 2 years old
• Closely linked to areas with limited healthcare access and low socioeconomic status
• Risk factors include:
  • Multiple prior episodes of acute otitis media (AOM)
  • AOM in the first few months of life
  • Chronic secretory otitis media
  • Genetic predisposition (higher incidence in some indigenous populations)
  • Craniofacial abnormalities (e.g., cleft palate)
  • Immunodeficiency

Classification (Types)

1. Tubotympanic (Safe / Benign) Type

2. Atticoantral (Unsafe / Malignant) Type

Pathogenesis and Pathophysiology

1. ET dysfunction - Abnormal ET function reduces aeration of the middle ear (ME) space. Nitrogen-absorbing cells in the mastoid cause volume reduction; negative pressure develops in the ME space.
2. Persistent effusion and infection - Serous or purulent effusion leads to mucosal edema. Bacterial infection (particularly polymicrobial) generates an inflammatory response. Chemical mediators promote chronic mucosal changes; the ME mucosa develops submucosal glands converting it to a secretory mucosa, perpetuating the effusion.
3. Granulation tissue formation - Bacterial toxins and inflammatory mediators interact with edematous mucosa, rupturing the basement membrane of the epithelia. Inflammatory cells and lamina propria components extrude into the ME lumen. Angiogenic and epithelial growth factors drive fibroblast recruitment, neovascularization, and polyp formation.
4. TM weakening and perforation - Enzymes in the granulation tissue and chronic effusion degrade the collagen skeleton of the TM. Negative ME pressure combined with a weakened TM causes retraction pockets and eventually perforation. Deep retraction pockets create the conditions for cholesteatoma genesis.
5. Biofilm formation - Bacterial biofilms are common in CSOM. These are highly organized, sessile bacterial communities encased within oligopolysaccharide matrices that:
   • Escape phagocytosis and humoral immunity
   • Show dramatically increased antibiotic resistance (produce efflux pumps)
   • Are frequently polymicrobial
   • Elicit ongoing host inflammatory responses via endo- and exotoxins
   • Pseudomonas aeruginosa is the most common pathogen in OM biofilms

Microbiology

Clinical Features

Symptoms

• Chronic/recurrent otorrhea - The cardinal symptom; may be intermittent, often malodorous (especially in atticoantral type)
• Hearing loss - Typically conductive, low-frequency; a mixed loss may be seen with ossicular erosion or labyrinthine involvement
• Aural fullness
• Otalgia and headache - Uncommon in uncomplicated CSOM; their presence should raise suspicion of intracranial involvement or malignancy
• Vertigo - Should raise suspicion of labyrinthitis or labyrinthine fistula

Signs

• TM perforation (central in tubotympanic; marginal/pars flaccida retraction pocket in atticoantral)
• Otorrhea often obscures the TM
• EAC edema or polyps (an aural polyp should be considered cholesteatoma until proven otherwise)
• Granulation tissue (check for scutal erosion and ossicular erosion)
• Cholesteatoma (pearl-white debris, usually arising from pars flaccida)
• Signs of complications: facial nerve paresis/paralysis, nystagmus, signs of intracranial infection

Audiometry

• Conductive hearing loss most common
• Some patients have SNHL (studies report 5-33 dB SNHL)
• Conductive loss >30 dB suggests ossicular erosion
• Occasionally, hearing can be preserved even with ossicular erosion if sound transmission occurs directly via the cholesteatoma to the oval window

Imaging

CT Temporal Bone (HRCT)

• Tubotympanic type: Haziness of the whole middle ear cleft; truncated pneumatization
• Pars flaccida cholesteatoma: Erosion of the scutum (on axial and coronal bone window CT); medialization of the ossicular chain; truncated mastoid pneumatization

• Pars tensa cholesteatoma: Erosion of the posterior-superior EAC wall; lateralization of ossicular chain; haziness medial to ossicular chain; possible erosion of the lateral semicircular canal; scutum NOT eroded

Indications for CT:

• Suspected or confirmed cholesteatoma
• Complicated CSOM (facial nerve paralysis, vertigo)
• Surgical planning
• Revision tympanomastoidectomy cases

MRI with Contrast:

Complications

Extracranial Complications

Intracranial Complications

Intracranial and extracranial complications may result from acute or chronic infections via direct extension through bone (via Haversian canals, air cell tracts, or congenital dehiscences) or hematogenous spread. Cholesteatoma is frequently present in complications of CSOM.

Diagnosis

1. Clinical history and otomicroscopic examination - Detailed history of otorrhea, prior ear surgery, antibiotics used. Otomicroscopy with pneumatic insufflation is the standard
2. Audiometry - Full audiometric evaluation (PTA, tympanometry)
3. Imaging - HRCT temporal bone (surgical planning, suspected cholesteatoma, complicated CSOM); MRI with contrast for intracranial complications
4. Biopsy - Biopsy of granulation tissue unresponsive to topical therapy to rule out malignancy. Remember: persistent CSOM is a recognized risk factor for squamous cell carcinoma of the temporal bone (68% of SCC cases in one series had prior CSOM)
5. Microbiological swab - For targeted antibiotic therapy

Treatment

Goals

• Dry = no otorrhea
• Safe = no collection of keratin debris, reduced risk of suppurative complications

Medical Treatment

1. Aural toilet (ear cleansing) - Suction debridement under microscope; removes debris, biofilm, and discharge. This alone can dry the ear in many cases.
2. Topical ototopical antibiotics (first-line):
   • Fluoroquinolones (ciprofloxacin or ofloxacin drops) - Drug of choice due to P. aeruginosa coverage and safety profile
   • Acetic acid/alcohol - Antiseptic properties, anti-Pseudomonal
   • Polymyxin B or neomycin (+/- steroid) - Used with caution (potential ototoxicity if TM perforated)
   • Typical course: 4-6 weeks following debridement
   • Note: Biofilms are frequently resistant to topical medication due to multicellular defense strategies
3. Systemic antibiotics - Generally reserved for:
   • Signs of complications (mastoiditis, facial nerve palsy)
   • Inadequate response to topical treatment
   • Immunocompromised patients
4. Water precautions - Keep water out of the affected ear

Surgical Treatment

Indications for Surgery

• Cholesteatoma combined with medically refractory CSOM - nearly absolute indication
• Retraction pockets that collect debris and progress
• Persistent otorrhea despite adequate medical treatment (multiple failed attempts)
• Symptoms suspicious for complications (vertigo, facial weakness, headache)
• Atelectatic ears with significant conductive hearing loss
• Hearing restoration

Surgical Options

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

• CWD offers lower recurrence rates in some studies, but others show the anatomical position of cholesteatoma (not the canal wall) more significantly impacts recurrence
• CWU provides better aesthetics and hearing outcomes but requires strict surveillance
• An open CWD cavity is not aesthetically ideal and requires regular lifetime follow-up and debridement

Eustachian Tube Treatment

CSOM and Cochlear Implantation

• Staged approach: Stage 1 - radical mastoidectomy with ET obliteration and canal oversewing (±mastoid obliteration); Stage 2 - CI after 3-6 months when ear is dry
• Single-stage: In patients with stable, dry cavity - blind sac closure + CI can be performed simultaneously
• Bacterial and fungal biofilms on CI electrodes are a real risk; Candida species found in 35% of ears treated with topical ciprofloxacin
• All CI candidates with CSOM receive antimicrobial prophylaxis before implantation
• The major risk of canal closure/mastoid obliteration is cholesteatoma formation, which is difficult to monitor post-CI due to MRI artefacts from the device

Key Points Summary

• Shambaugh Surgery of the Ear, 6th ed. - Etiology, diagnosis, and medical/surgical treatment of CSOM (pp. 527-529)
• Cummings Otolaryngology Head and Neck Surgery - Complications of otitis media (p. 2704)
• K.J. Lee's Essential Otolaryngology, 11th ed. - Epidemiology, etiology, and treatment (pp. 445-447)
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Vol. 2 - CSOM and temporal bone malignancy (p. 1469)