Chronic Suppurative Otitis Media (CSOM) — Tubotympanic vs Atticoantral, Cholesteatoma and Complications

Chronic suppurative otitis media (CSOM) is a chronic infection and inflammation of the middle ear cleft with persistent or recurrent otorrhoea through a perforated tympanic membrane, usually with conductive hearing loss. StatPearls notes that the duration used in definitions ranges from 2 to 6 weeks, and that the discharge classically lasts more than 6 weeks by the time the patient is seen.

CSOM usually follows an untreated, inadequately treated or recurrent acute otitis media that leaves a permanent perforation. Trauma and iatrogenic causes (grommets, previous ear surgery) can do the same. The middle ear connects to the nasopharynx through the eustachian tube and to the mastoid air cells through the aditus and antrum — which is why infection here can spread to the mastoid, the inner ear, the facial nerve and the brain.

It is a disease of poverty: overcrowding, malnutrition, poor sanitation, passive smoking and limited access to care all raise the risk. Structural risk factors include cleft palate, Down syndrome and other craniofacial anomalies. StatPearls estimates that CSOM affects about 1 in 26 people worldwide and is a leading cause of preventable hearing loss.

CSOM is divided into two types that behave very differently. The split is clinical and decided at otoscopy: where is the perforation, and is there cholesteatoma?

CSOM is usually polymicrobial. The common isolates are *Pseudomonas aeruginosa* (the most frequent), *Staphylococcus aureus*, Proteus, Klebsiella, diphtheroids and anaerobes, sometimes with fungi. These bacteria form biofilms on the middle-ear mucosa, which protect them from host defences and antibiotics and explain why discharge keeps coming back.

• Eustachian tube dysfunction — negative middle-ear pressure, fluid stasis and mucosal oedema.
• Persistent perforation — bacteria, water and debris enter from the ear canal; patients notice more discharge after bathing or swimming.
• Chronic mucosal inflammation — granulation tissue, mucosal thickening and loss of mucociliary clearance.
• Squamous metaplasia of the middle-ear lining in long-standing disease.
• Ossicular erosion — progressive conductive hearing loss.

Cholesteatoma is a misnomer — it contains neither cholesterol nor fat. It is keratinising stratified squamous epithelium growing in the middle ear and mastoid, a sac that keeps filling with keratin debris. Although benign, it destroys bone by pressure-induced resorption and enzymatic (osteoclastic) bone resorption driven by inflammatory cytokines. Inside the cranium the same lesion is called an epidermoid cyst.

On otoscopy a cholesteatoma looks like a white, pearly or yellow mass in a retraction pocket, typically in the posterosuperior quadrant, often hidden under foul discharge. StatPearls describes the classic presentation as painless, persistent or recurrent otorrhoea; about 85% are unilateral. Vertigo suggests erosion of the labyrinth (a fistula).

Diagnosis is clinical — history plus otoscopy. Look for a long history of discharge (often since childhood), hearing loss noticed as poor school performance or speech delay in children, and the type of perforation. Ask about vertigo, facial weakness, headache, fever or vomiting: these suggest a complication.

1. Aural toilet — mechanical removal of discharge and debris (suction and microinstruments under the otomicroscope). It lets topical drops reach the middle ear and is the foundation of treatment.
2. Topical fluoroquinolone drops (ciprofloxacin, ofloxacin) — first line. They cover Pseudomonas and S. aureus and are not ototoxic even with a perforation.
3. Avoid ototoxic drops — aminoglycoside drops (neomycin, gentamicin) are cheap and effective but can cause sensorineural loss and vestibular damage when the drum is perforated.
4. Granulation tissue control — topical steroid–antibiotic drops or chemical cautery with silver nitrate.
5. Systemic antibiotics — only for systemic infection, complications, or failure of topical therapy; guided by culture.
6. Dry-ear precautions — keep water out of the ear.
7. Topical antiseptics — an alternative where antibiotic drops are not available (WHO guidance for low-resource settings).

StatPearls lists the indications for surgery as otorrhoea persisting 4–6 weeks despite medical treatment, a perforation that does not heal, cholesteatoma, conductive hearing loss and coalescent mastoiditis. Possible contraindications include operating on the only hearing ear, poor general health or high anaesthetic risk, or severe complications such as brain abscess that need treating first.

The goal of cholesteatoma surgery is a safe, dry ear first, and hearing second. Recurrence is common — in one study quoted in StatPearls, the 5-year recurrence after primary surgery was 38% in children vs 14% in adults. Many surgeons plan a second-look operation at 6–12 months or follow up with diffusion-weighted MRI.

Complications arise mainly from atticoantral disease with cholesteatoma. Infection spreads by bone erosion, through thrombophlebitis of small veins, and along pre-formed pathways. They are classically split into intratemporal (extracranial) and intracranial.

Otogenic abscess reaches the temporal lobe through erosion of the tegmen tympani, and the cerebellum through Trautmann's triangle or by thrombophlebitis of the sigmoid sinus. In one series reported in PMC, about 95% of otogenic brain abscesses occurred with chronic otitis media and cholesteatoma. Meningitis and brain abscess remain the main causes of death from otitis media.

• Otoscopy image — central perforation (safe) vs attic/marginal perforation with white keratin (unsafe).
• Most common organism — Pseudomonas aeruginosa.
• Theories of cholesteatoma — retraction pocket, epithelial migration, squamous metaplasia, basal cell hyperplasia (Prussak's space).
• Commonest site of labyrinthine fistula — lateral semicircular canal.
• Griesinger sign and Gradenigo syndrome — match the sign to the complication.
• Most common intracranial complication — meningitis; brain abscess sites — temporal lobe and cerebellum.
• Investigation of choice — HRCT temporal bone for bone; DWI-MRI for cholesteatoma and intracranial spread.
• Topical treatment — quinolone drops; aminoglycoside drops are ototoxic through a perforation.