Chronic and acute otitis media

Definition / Overview

Chronic otitis media (COM) is persistent inflammatory disease of the middle ear and mastoid lasting more than 12 weeks, encompassing a spectrum from inactive mucosal disease with a dry perforation through to active suppurative disease and cholesteatoma with bony destruction.

• Cholesteatoma is a keratinising squamous epithelial cyst of the middle ear and/or mastoid, capable of progressive bony erosion through osteolytic enzyme activity.
• Despite the name, it contains neither fat nor cholesterol; "keratoma" more accurately describes the lesion.
• Cholesteatoma represents the most surgically dangerous form of COM due to its capacity to erode the ossicular chain, labyrinth, tegmen, and facial nerve canal.

Classification of COM

Pathophysiology

Mucosal Chronic Otitis Media

• Recurrent acute otitis media and Eustachian tube (ET) dysfunction lead to persistent middle ear inflammation, mucosal metaplasia, and failure of tympanic membrane (TM) healing.
• The resulting permanent perforation is typically central (not involving the annulus) and carries a lower risk of cholesteatoma than marginal perforations.
• Ongoing infection produces a biofilm dominated by Pseudomonas aeruginosa and Staphylococcus aureus.

Cholesteatoma Formation

• ET dysfunction generates chronic negative middle ear pressure.
• The pars flaccida (Shrapnell's membrane), lacking the fibrous middle layer of the pars tensa, is the most susceptible region to retraction.
• Progressive retraction produces a pocket that accumulates desquamated keratin.
• Most acquired cholesteatomas arise from this pars flaccida retraction mechanism; a minority arise from pars tensa marginal perforations through which squamous epithelium migrates.

Four principal theories of formation are recognised:

• Retraction/invagination (most common): progressive pars flaccida retraction and keratin trapping
• Epithelial immigration: squamous epithelium migrates through a marginal perforation
• Squamous metaplasia: chronic inflammation transforms middle ear mucosal epithelium
• Basal cell hyperplasia: proliferation of basal keratinocytes through the basement membrane
• Keratin matrix produces matrix metalloproteinases and osteoclast-activating cytokines (including receptor activator of nuclear factor-$\kappa$B ligand), driving progressive bone resorption.
• This underlies erosion of the ossicular chain, scutum, tegmen, lateral semicircular canal (SCC), and facial nerve canal.

Congenital Cholesteatoma

• Presents as a white, pearl-like mass behind an intact TM, most commonly in the anterosuperior quadrant.
• No history of infection or perforation.
• Originates from an epithelial rest (epidermoid formation) that fails to involute during embryogenesis.

Clinical Features and Diagnosis

History

• Otorrhoea: typically painless, persistent, often foul-smelling (particularly with cholesteatoma)
• Conductive hearing loss (CHL): degree reflects ossicular chain integrity
• Otalgia: suggests acute exacerbation, complication, or malignancy
• Vertigo or disequilibrium: raises concern for labyrinthine fistula
• Facial weakness: urgent red flag; indicates facial nerve involvement
• Headache, meningism, neurological symptoms: suggest intracranial complication

Examination

• Otoscopy / microscopy: required for adequate assessment; note TM status, site and size of perforation, retraction pockets, keratin debris, granulation tissue, polyps
• Pars flaccida vs pars tensa: attic (pars flaccida) perforations or crust accumulation strongly suggest cholesteatoma
• Marginal perforation: higher cholesteatoma risk than central perforations
• Siegelisation (pneumatic otoscopy): assesses retraction pocket mobility and fixation
• Facial nerve function: document HB grade at every visit
• Tuning fork tests: Weber and Rinne to characterise hearing loss

Audiological Assessment

• Pure tone audiogram (PTA) with air and bone conduction: quantifies CHL; sensorineural component suggests cochlear or inner ear involvement
• Tympanometry: type B (flat) with large volume suggests perforation; restricted mobility suggests effusion or ossicular fixation
• Speech discrimination testing: important for surgical planning and hearing rehabilitation counselling

Investigation

Imaging

CT of the temporal bones (non-contrast, high-resolution) is the primary imaging modality:

• Identifies extent of disease, bony erosion, and anatomical landmarks
• Relative indications: revision surgery, only hearing ear, TM not fully visualised, suspected labyrinthine fistula, facial weakness, previous surgery
• Absolute indications: suspected intracranial complication, suspected facial nerve involvement
• CT cannot reliably distinguish residual/recurrent cholesteatoma from fluid or granulation tissue post-operatively

MRI (non-echo-planar diffusion-weighted imaging, DWI) is increasingly used for:

• Detecting residual or recurrent cholesteatoma post-operatively (sensitivity ~90% for lesions >5 mm)
• Non-echo-planar (HASTE) DWI has higher specificity than standard EP-DWI due to reduced susceptibility artefact
• Pre-operative characterisation when CT findings are equivocal

Microbiological Swab

• Take aural swab when active discharge is present
• Guides topical and systemic antimicrobial selection
• Particularly important for treatment-refractory cases or suspected resistant organisms

Medical Management

Aural Toilet

• Regular microsuction or dry mopping is foundational.
• It removes keratin debris, reduces biofilm load, and allows adequate examination and delivery of topical agents.
• Performed in clinic under microscopy; frequency titrated to disease activity.

Topical Antimicrobials

• Ciprofloxacin-based otic drops: first-line for active COM discharge; effective against Pseudomonas and Staphylococcus; safe with a perforation
• Aminoglycoside-containing drops (e.g. gentamicin, neomycin): avoid with a perforation due to cochlear and vestibular toxicity
• Alcohol or acetic acid preparations: avoid with perforation; caustic to middle ear mucosa
• Topical steroid combinations reduce granulation tissue and mucosal oedema

Systemic Antimicrobials

• Reserve for acute exacerbations unresponsive to topical therapy
• Broad-spectrum oral agents with anti-pseudomonal coverage (e.g. oral ciprofloxacin) for 3-4 weeks
• Parenteral therapy for persistent drainage or suspected spreading infection
• Culture-directed therapy when empirical treatment fails

Water Precautions

• Custom-fit or off-the-shelf ear plugs during water exposure.
• Essential patient education at every consultation.

Eustachian Tube Dysfunction

• Topical intranasal corticosteroids and management of rhinosinusitis may reduce recurrent acute otitis media episodes and slow retraction pocket progression.
• Decongestants have limited evidence.
• Definitive management of cholesteatoma is always surgical.
• Medical treatment is temporising only: it reduces active discharge and optimises conditions for surgery, but cannot eradicate cholesteatoma.

Surgical Management

Principles of Surgery

Surgical objectives in priority order:

1. Eradicate disease (safe, dry ear; remove all cholesteatoma matrix)
2. Prevent complications (intracranial, labyrinthine, facial nerve)
3. Preserve or restore hearing (ossiculoplasty, tympanoplasty)
4. Achieve a self-maintaining ear (avoid mandatory lifelong cavity care where possible)

Tympanoplasty

• Surgical reconstruction of the TM, with or without ossicular chain reconstruction (OCR).
• Performed for non-healing perforations, recurrent infection, CHL, or co-existing cholesteatoma.

Graft materials:

• Temporalis fascia: most commonly used; reliable take rate; harvested via post-auricular or endaural approach
• Perichondrium/cartilage: preferred for retraction-prone areas (pars flaccida reconstruction), large perforations, and revision cases
• Fat (lobule): for small perforations via myringoplasty technique

Overlay (lateral) vs underlay (medial) technique:

• Underlay (medial surface of TM remnant): most common; lower risk of epithelial inclusion cholesteatoma
• Overlay: used for large anterior perforations; higher blunting risk

Success rates are influenced by: contralateral ear status, ET function, patient age, presence of active infection at time of surgery, and perforation size.

Ossicular Chain Reconstruction (OCR)

Performed at time of tympanoplasty or as a staged procedure. Erosion pattern dictates prosthesis selection:

Materials: titanium, hydroxyapatite, or autologous cortical bone/incus.

Mastoidectomy: Canal Wall Up (CWU)

Also called intact canal wall mastoidectomy or closed cavity mastoidectomy.

• Mastoid air cells are exenterated, the posterior canal wall is preserved
• Combined approach tympanoplasty (CAT) uses both transcanal and transmastoid routes for cholesteatoma clearance
• Advantages: preserves normal canal anatomy; water-safe ear; better hearing aid fitting; no mandatory cavity care
• Disadvantages: reduced intraoperative access, particularly to epitympanum and sinus tympani; increased risk of residual/recurrent cholesteatoma; mandates planned second-look procedure at 9-18 months (or surveillance DWI MRI as an alternative)

Indications for CWU:

• Limited cholesteatoma with accessible disease
• Intact or reconstructable posterior canal wall
• Reliable patient for post-operative surveillance
• Children (preserving canal anatomy preferred where technically achievable)

Mastoidectomy: Canal Wall Down (CWD) / Modified Radical Mastoidectomy

The posterior and superior canal wall are removed, creating an open mastoid cavity (the "bowl") that communicates with the external auditory canal.

• Modified radical mastoidectomy: canal wall down with tympanoplasty; TM remnant and as many ossicles as possible are preserved to rehabilitate hearing
• Radical mastoidectomy: canal wall down, all ossicles except stapes footplate removed, no attempt at hearing reconstruction; reserved for extensive irreparable disease

Key technical steps in CWD:

1. Create a large meatoplasty (meatal skin and cartilage trimmed) to ensure adequate ventilation and easy inspection of the cavity
2. Lower the facial ridge to the level of the facial nerve
3. Remove all mastoid air cells, including the retrofacial cells
4. Obliterate dead space where possible (musculoperiosteal flap, abdominal fat)

Advantages of CWD: superior intraoperative access; all disease directly visualised; recurrent cholesteatoma more readily detected at outpatient review; lower residual/recurrence rate.

Disadvantages of CWD: lifelong cavity maintenance (regular microsuction, typically 6-monthly); risk of otorrhoea from water/cold air (caloric stimulation); difficulty with hearing aid fitting (can be addressed with bone-anchored devices); mastoid bowl syndrome.

Indications for CWD:

• Extensive cholesteatoma with eroded posterior canal wall
• Erosion of the lateral SCC
• Only hearing ear (when recurrence risk must be minimised)
• Non-compliant or geographically remote patient unlikely to attend second-look
• Multiple recurrences after prior CWU surgery
• Labyrinthine fistula with accessible disease

Bondy Modified Radical Mastoidectomy

• A variant of CWD specifically for isolated epitympanic or mastoid cholesteatoma with intact pars tensa and good hearing.
• The tympanomeatal flap is not raised and the ossicular chain is left intact; only the attic and mastoid disease is exteriorised.
• Appropriate when cholesteatoma is confined entirely to the epitympanum and mastoid without middle ear involvement.

Cortical (Simple) Mastoidectomy

Exenteration of mastoid air cells without disturbing the canal wall or middle ear. Used for:

• Acute coalescent mastoiditis not responding to antibiotics
• Access procedure (cochlear implantation, endolymphatic sac surgery, facial nerve decompression, skull base approaches)
• Not appropriate as primary treatment for cholesteatoma

Staged vs Single-Sitting Surgery

• Single-sitting: appropriate when confident of complete disease removal and acceptable hearing reconstruction conditions
• Staged procedure: CWU mastoidectomy for cholesteatoma commonly staged: first sitting for disease clearance; second-look at 9-18 months for detection of residual disease and OCR
• DWI MRI surveillance is an increasingly accepted alternative to routine second-look in selected patients

Complications of Chronic Otitis Media and Cholesteatoma

Extracranial (Temporal Bone) Complications

Intracranial Complications

• Meningitis: most common intracranial complication; via tegmen erosion or haematogenous spread
• Sigmoid sinus thrombophlebitis: septic thrombosis; presents with spiking fevers, headache; requires anticoagulation and surgical drainage
• Extradural (epidural) abscess: pus between dura and temporal bone; CT/MRI diagnosis; neurosurgical or combined approach
• Subdural empyema and brain abscess: temporal lobe or cerebellar; life-threatening; neurosurgical emergency
• Otitic hydrocephalus: raised ICP without focal lesion; lateral sinus thrombosis mechanism

Any suspected intracranial complication requires urgent CT/MRI, neurosurgical consultation, high-dose IV antibiotics, and surgical planning without delay.

Special Considerations

Cholesteatoma in Children

• Higher recurrence rates than adults due to more aggressive disease and ongoing ET dysfunction
• CWU preferred where technically feasible to preserve canal anatomy and hearing potential
• Lower threshold for second-look procedure
• Congenital cholesteatoma detected early (stage I: limited to middle ear anterior to ossicles) can sometimes be excised via a transcanal approach without mastoidectomy

Labyrinthine Fistula Management

• Lateral SCC fistula is the most common site; detected on CT and confirmed intraoperatively
• Small fistula (matrix over denuded bone): matrix may be left intact over the fistula and covered with fascia; hearing preservation is priority
• Large fistula with matrix removed: risk of profound SNHL and vertigo; weigh against risk of leaving matrix and residual disease
• Inform patient pre-operatively of risk of sensorineural hearing loss and discuss implications

Facial Nerve Considerations

• Facial nerve dehiscence is common in COM/cholesteatoma (second genu and tympanic segment most vulnerable)
• Pre-operative facial function must be documented
• Intraoperative facial nerve monitoring is standard of care in revision and complex cases
• If facial palsy arises from cholesteatoma, surgical decompression and matrix removal takes precedence over hearing preservation

Only-Hearing Ear

• Surgical risk-benefit discussion is critical: risk of dead ear must be weighed against progressive destruction and complication risk from untreated cholesteatoma
• CWD preferred to minimise residual/recurrent disease requiring further surgery
• Hearing rehabilitation planning (bone-anchored hearing system, contralateral routing of signal) discussed pre-operatively

Perioperative and Long-term Management

Pre-operative Assessment

• Optimise ear: treat active infection, achieve dryest possible ear before elective reconstruction
• Full audiological assessment including speech discrimination and contralateral ear status
• CT temporal bone for all cholesteatoma cases
• Informed consent: hearing preservation and improvement (quantify risk of SNHL, dead ear); facial nerve injury; recurrence and need for further surgery; cavity care; taste disturbance (chorda tympani); tinnitus

Post-operative Care

• CWU: clinic review at 2-3 weeks for pack removal; audiogram at 6-8 weeks; second-look or surveillance MRI at 9-18 months
• CWD: cavity care at 4-6 weeks post-operatively; thereafter 6-monthly microsuction lifelong; patient education regarding water precautions and avoidance of cold air in the cavity
• Water precautions for all patients with open perforations or mastoid cavities until cavity epithelialises

Hearing Rehabilitation

• Post-operative audiogram at 6-8 weeks guides rehabilitation planning
• Hearing aids: conventional if canal and TM stable; osseointegrated bone-anchored hearing systems for CWD cavities or failed middle ear reconstruction
• Cochlear implantation: considered for bilateral severe-to-profound SNHL, particularly if complication of COM; requires clearance of all infection/cholesteatoma first

Surveillance for Recurrence

• Clinical otomicroscopy annually for life in all operated COM patients
• DWI MRI surveillance at 18 months post-CWU mastoidectomy is an accepted alternative to routine second-look surgery in centres with radiological expertise
• Recurrent cholesteatoma after CWD is managed by return to theatre for cavity revision and disease clearance

Summary: Key Decision Points