CSOM - Chronic Suppurative Otitis Media: A Complete Overview

Definition

Classification

1. Tubotympanic (Safe/Benign) Type

• Perforation involves the pars tensa (central or subtotal)
• No cholesteatoma
• Associated with mucosal disease
• Discharge is mucoid or mucopurulent
• Considered "safe" - rarely causes serious complications

2. Atticoantral (Unsafe/Dangerous) Type

• Perforation involves the pars flaccida (attic/marginal)
• Cholesteatoma is present
• Bone erosion is a hallmark
• Discharge is scanty, foul-smelling (fetid)
• "Unsafe" - serious intracranial and extracranial complications possible

Pathophysiology / Etiology

1. ET dysfunction → negative middle ear pressure → persistent middle ear effusion (MEE)
2. The MEE causes mucosal edema, inflammatory mediator release, and mucosal metaplasia to a secretory type - perpetuating the effusion
3. Bacterial infection of the effusion → purulent discharge → rupture of the tympanic membrane basement membrane
4. Granulation tissue formation: inflammatory cells + lamina propria elements extrude through the basement membrane. Angiogenic and epithelial growth factors drive fibroblast recruitment, neovascularization, and polyp formation
5. Enzymatic weakening of the tympanic membrane: enzymes in the effusion and granulation tissue break down collagen - leading to retraction pockets and eventually perforation
6. Deep retraction pockets + perforations create the conditions for cholesteatoma genesis

Microbiology

Clinical Features

Symptoms

• Otorrhea: intermittent or persistent - the hallmark symptom
  • Tubotympanic type: mucoid/mucopurulent, not fetid
  • Atticoantral/cholesteatoma type: scanty, foul-smelling (fetid)
• Conductive hearing loss: virtually always present; CHL > 30 dB suggests ossicular erosion
• Otalgia and headache: uncommon in uncomplicated CSOM - their presence should raise suspicion of intracranial involvement or malignancy
• Vertigo: raises suspicion for labyrinthine fistula or labyrinthitis
• Occasionally blood-stained discharge with aural polyp formation

Signs (on otoscopy/otomicroscopy)

• Tympanic membrane perforation (central vs. marginal/attic)
• Discharge in the canal (may obscure the TM)
• Granulation tissue or aural polyps in the EAC
• Evidence of cholesteatoma (white, pearly mass, keratin flakes)
• Scutal erosion (bone erosion at the attic wall)
• Ossicular erosion may be visible through the perforation

Tympanic Membrane Perforation - Clinical Image

Tympanic membrane perforation with chronic inflammation (Cummings Otolaryngology)

Cholesteatoma - The Dangerous Component

Types

• Congenital: present behind an intact TM, no history of infection
• Acquired Primary: from deep retraction pocket of pars flaccida (attic), no prior perforation
• Acquired Secondary: keratinizing epithelium migrates through a pre-existing perforation

How Cholesteatoma Destroys Bone

• Cholesteatoma-bone contact → normal mucosal lining degenerates
• Macrophages, monocytes, and osteoclasts accumulate
• Elevated cytokines: TNF-α, IL-1α, IL-1β, IL-6, IFN-γ, EGF, PTHrp
• Lipopolysaccharides prime osteoclast precursors via RANKL pathway
• Nitric oxide type II enhances osteoclastic activation synergistically with IL-1β and TNF-α
• Result: progressive bone erosion of ossicular chain, scutum, tegmen, otic capsule, fallopian canal

Acquired cholesteatoma with keratinous debris in an attic retraction pocket (Shambaugh)

Pathology Without Cholesteatoma

• Granulation tissue in 96% of cases
• Ossicular changes in 96%
• Tympanosclerosis in 43%
• Cholesterol granuloma in 21%

Diagnosis

History

• Chronic intermittent otorrhea (character, duration, odor)
• Degree of hearing loss
• History of prior ear surgery or medical treatment
• Presence of vertigo, facial weakness, or headache (alarm features for complications)

Examination

• Full head and neck exam including otomicroscopy
• Note: EAC edema, polyps, discharge
• TM: perforation site, retraction, atelectasis, cholesteatoma
• Middle ear mucosa through perforation: granulation tissue, ossicular erosion, scutal erosion

Audiometry

• Conductive hearing loss - most common
• CHL > 30 dB: suggests ossicular erosion
• Sensorineural hearing loss (5-33 dB range in studies) - may coexist; must be documented preoperatively
• Note: hearing may be preserved despite ossicular erosion if sound transmits directly to oval window via cholesteatoma matrix

Imaging

• High-resolution CT temporal bone (HRCT): gold standard for evaluating extent of disease, bone erosion, cholesteatoma extent, tegmen integrity, facial nerve canal involvement
• MRI (non-echo planar DW-MRI): preferred for detecting residual/recurrent cholesteatoma, especially after surgery; avoids CI artifact issues
• Both modalities complementary in complex cases

Complications

Extracranial Complications

• Acute mastoiditis / Coalescent mastoiditis
• Postauricular abscess
• Bezold abscess (pus tracking along sternomastoid under deep cervical fascia)
• Temporal abscess
• Petrous apicitis (Gradenigo syndrome: triad of otorrhea, retroorbital pain, abducens palsy)
• Labyrinthine fistula (most commonly lateral semicircular canal)
• Facial nerve paralysis (erosion of the fallopian canal)
• Acute suppurative labyrinthitis
• Encephalocele and CSF leakage

Intracranial Complications

• Meningitis (most common intracranial complication)
• Brain abscess (temporal lobe or cerebellar)
• Subdural empyema
• Epidural abscess
• Lateral sinus thrombosis
• Otitic hydrocephalus

Medical Treatment

1. Aural toilet (ear suctioning/debridement) - removes debris, discharge, and biofilm; essential before topical therapy
2. Ototopical antibiotics: fluoroquinolones (ciprofloxacin/ofloxacin eardrops) are first-line - safe, effective, minimal ototoxicity
3. Systemic antibiotics: used if ototopical treatment insufficient or signs of systemic spread; guided by culture and sensitivity
4. Antifungal treatment: if fungal overgrowth suspected (especially post-antibiotic treatment); clotrimazole drops or systemic azoles
5. Avoid water contamination of the ear (ear protection during bathing)

• Failed multiple attempts at medical treatment
• Cholesteatoma (near-absolute indication for surgery)
• Symptoms suggesting complications: vertigo, facial weakness, headache
• Persistent/progressive disease despite adequate medical therapy

Surgical Treatment

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

Types of Surgery

Tympanoplasty (Myringoplasty for isolated TM perforation)

• Repair of TM perforation alone (Type I tympanoplasty) or with ossicular reconstruction
• Temporalis fascia is the most widely used graft material
• Underlay vs. overlay technique
• Success depends on: dry ear preoperatively, ET function, size/site of perforation

Mastoidectomy Types

Ossiculoplasty

• Reconstruction of eroded ossicular chain at time of tympanoplasty or at second stage
• Materials: autologous cartilage/bone, PORP (Partial Ossicular Replacement Prosthesis), TORP (Total Ossicular Replacement Prosthesis)

Second-Look Surgery

CSOM and Cochlear Implantation

• Staged approach: first stage clears disease (radical mastoidectomy ± mastoid obliteration), CI performed 2-6 months later when the ear is dry
• If a stable, dry cavity exists, single-stage blind sac closure + CI may be feasible
• Microbial biofilms (bacterial or fungal) on the CI are a significant risk - must be eradicated before implant insertion
• All patients receive antimicrobial prophylaxis perioperatively

Summary Table

• Shambaugh Surgery of the Ear, pp. 527-529, 453-454, 466
• Cummings Otolaryngology Head and Neck Surgery, pp. 2690, 3072-3073, Box 141.1
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery Vol. 2, p. 142