Chronic Suppurative Otitis Media (CSOM)
ENT · Ear · lean revision notes
Chronic Suppurative Otitis Media (CSOM)
CSOM is a chronic inflammation of the middle ear cleft (Eustachian tube, middle ear, attic, aditus, antrum, mastoid air cells) presenting with a permanent perforation of the tympanic membrane and recurrent or persistent ear discharge for more than 6–12 weeks. The single most important exam concept is splitting CSOM into the tubotympanic ("safe") type and the atticoantral ("unsafe"/cholesteatoma) type, because almost every NEET PG vignette hinges on recognising which one carries the risk of intracranial complications.
High-yield: "Safe" vs "unsafe" is decided by the type of perforation and the presence of cholesteatoma/bone erosion, NOT by how foul the discharge smells alone — though scanty, foul, blood-stained discharge points to unsafe disease.
Definition & Classification
A perforation persisting >3 months with discharge defines chronic disease. CSOM is classically divided into two clinico-pathological types:
| Feature | Tubotympanic (Safe) | Atticoantral (Unsafe) |
|---|---|---|
| Other name | Mucosal / benign type | Squamosal / dangerous type |
| Perforation | Central (pars tensa, margin of TM intact) | Marginal or attic (pars flaccida) |
| Cholesteatoma | Absent | Present (defining feature) |
| Discharge | Profuse, mucoid/mucopurulent, odourless, non-blood-stained | Scanty, purulent, foul-smelling, often blood-stained |
| Granulations/polyp | Uncommon | Common (aural polyp, granulation tissue) |
| Hearing loss | Mild–moderate conductive | Variable; can be severe, may become mixed/SNHL |
| Bone erosion (ossicles, scutum) | Absent | Present |
| Complications | Rare | Common & dangerous |
| Discharge activity | Active phase alternates with dry phase | Persistent / recurrent |
High-yield: Attic (pars flaccida) and marginal perforations are unsafe; a central perforation is safe. This single line answers a large fraction of CSOM MCQs.
Active mucosal disease = discharging; inactive/quiescent = dry central perforation with hearing loss but no active discharge.
Etiology & Pathophysiology
Tubotympanic type
Usually a sequel of acute otitis media in childhood that failed to heal, or persistent Eustachian tube dysfunction. Common organisms in the chronically discharging ear are Pseudomonas aeruginosa (commonest in CSOM), Staphylococcus aureus, Proteus, Klebsiella, and anaerobes (Bacteroides). The mucosa shows oedema, ciliary loss, and goblet-cell metaplasia producing the copious mucoid discharge.
High-yield: Pseudomonas aeruginosa is the commonest organism isolated from a chronically discharging ear; Staph aureus is next.
Cholesteatoma (the engine of unsafe disease)
Cholesteatoma is a sac of stratified keratinising squamous epithelium in the middle ear that accumulates keratin debris ("keratin pearl"). It is not a tumour despite the "-oma" suffix; the misnomer matters because its danger is bone erosion, not malignancy.
Theories of acquired cholesteatoma:
- Retraction pocket / invagination theory (Wittmaack) — most accepted; persistent negative middle-ear pressure pulls pars flaccida medially, forming a pocket that traps keratin.
- Epithelial invasion / migration theory (Habermann) — squamous epithelium migrates through a marginal perforation.
- Basal cell hyperplasia / papillary ingrowth theory (Ruedi) — proliferation of basal cells of pars flaccida.
- Squamous metaplasia theory (Sade) — middle-ear mucosa undergoes metaplasia to keratinising epithelium.
Congenital cholesteatoma arises behind an intact tympanic membrane (embryonic epidermoid rest), classically seen as a white mass in the anterosuperior quadrant with no perforation and no history of discharge — a favourite distractor.
Why cholesteatoma erodes bone: The matrix releases osteolytic enzymes (collagenase), and pressure necrosis plus osteoclast activation (RANKL, cytokines) destroy the ossicles and surrounding bone. Erosion of the scutum is the earliest CT sign.
High-yield: Cholesteatoma = "skin in the wrong place." It causes destruction by enzymatic osteolysis + pressure necrosis, eroding ossicles → discontinuity → conductive deafness, and can breach the bony walls → intracranial spread.
Flow of unsafe disease:
Eustachian dysfunction → negative middle-ear pressure → pars flaccida retraction pocket → keratin accumulation → cholesteatoma → bone/ossicular erosion → complications.
Clinical Features
Symptoms
- Ear discharge (otorrhoea): the cardinal feature. Distinguish character as above (profuse odourless mucoid in safe vs scanty foul blood-stained in unsafe).
- Hearing loss: conductive, due to perforation and/or ossicular erosion. A large ossicular-chain disruption can paradoxically cause better hearing in unsafe disease when the cholesteatoma bridges the gap ("cholesteatoma hearer") — a classic trap.
- Earache (otalgia): uncommon in uncomplicated disease; pain signals impending complication (e.g., mastoiditis, abscess).
- Tinnitus / vertigo: suggest labyrinthine involvement (fistula).
- Facial weakness, fever, headache, neck rigidity: red flags for complications.
Signs (otoscopy)
- Safe: central perforation in pars tensa; middle-ear mucosa pink and oedematous; ossicles usually visible.
- Unsafe: attic perforation / crust over pars flaccida, marginal perforation, aural polyp, granulation tissue, whitish keratin flakes (pearly debris).
High-yield: An aural polyp arising from the attic = cholesteatoma until proven otherwise. A polyp arising from the promontory through a central perforation suggests safe mucosal disease. Never avulse a polyp blindly — it may be attached to the facial nerve, stapes footplate, or dura → meningitis/facial palsy.
Diagnosis & Investigation of Choice
A clinical diagnosis is made by otoscopy/otomicroscopy (gold standard for examining the perforation type, attic, and cholesteatoma). Supportive tests:
| Investigation | Purpose / finding |
|---|---|
| Otomicroscopy / EUM (exam under microscope) | Best to define perforation margin, attic, cholesteatoma sac |
| Pure tone audiometry | Quantifies conductive (or mixed) loss, baseline before surgery |
| Tuning fork tests | Rinne negative in affected ear; Weber lateralises to diseased ear (conductive) |
| HRCT temporal bone | Investigation of choice for unsafe disease/complications — shows scutum erosion, ossicular destruction, soft-tissue density, mastoid extent, fistula, tegmen/dural plate dehiscence |
| MRI (DW – diffusion weighted) | Differentiates recurrent/residual cholesteatoma (restricted diffusion, bright) from granulation/fluid; best for intracranial complications |
| Culture & sensitivity of discharge | Guides topical/systemic antibiotics |
| Fistula test | Positive (vertigo/nystagmus on tragal pressure) → lateral semicircular canal fistula |
High-yield: HRCT temporal bone is the imaging investigation of choice to map cholesteatoma extent and bony erosion before mastoid surgery; DW-MRI is best for residual/recurrent cholesteatoma without re-operation.
Management & Drug of Choice
Tubotympanic (safe) type
Aim: control infection, keep ear dry, then close the perforation.
- Aural toilet — dry mopping/suction clearance (single most important conservative step).
- Topical antibiotic drops — ciprofloxacin (fluoroquinolone) ear drops are the drug of choice because they cover Pseudomonas and, unlike aminoglycosides (gentamicin/neomycin), are non-ototoxic — preferred when the perforation is open.
- Treat focus of sepsis (sinusitis, adenoids, allergy).
- Surgery once dry:
- Myringoplasty — repair of TM perforation alone (graft: temporalis fascia, tragal/conchal cartilage-perichondrium).
- Tympanoplasty — repair of TM ± reconstruction of ossicular chain (Wullstein types I–V). Type I = myringoplasty with intact mobile ossicles.
High-yield: Avoid aminoglycoside ear drops when the TM is perforated (risk of cochleotoxicity); topical ciprofloxacin is first-line for the discharging safe ear.
Atticoantral (unsafe) type
Surgery is mandatory — medical therapy alone never cures cholesteatoma; the goal is eradication of disease first, hearing reconstruction second.
- Canal wall down (CWD) mastoidectomy — modified radical mastoidectomy (preserves middle-ear remnant/ossicles where possible) or radical mastoidectomy (exenterates all middle-ear contents, eustachian tube packed) for extensive/complicated disease. Creates an open cavity for surveillance — lowest recurrence.
- Canal wall up (CWU) / intact-canal-wall mastoidectomy — better hearing & no open cavity, but higher residual/recurrent cholesteatoma; needs second-look surgery (or DW-MRI surveillance).
- Atticotomy for limited attic cholesteatoma.
High-yield: In unsafe CSOM the principle is "disease eradication takes priority over hearing" — removal of cholesteatoma and a safe dry ear outranks hearing gain. Modified radical mastoidectomy is the classic operation when ossicles/remnant can be preserved.
Stepwise decision flow:
Otorrhoea >3 months → otoscopy → central perforation (safe) → aural toilet + ciprofloxacin drops → tympanoplasty when dry. Attic/marginal perforation or cholesteatoma (unsafe) → HRCT → mastoidectomy (CWD/CWU) ± tympanoplasty.
Complications
These flow from spread of infection/erosion from the middle-ear cleft. Almost exclusively in unsafe (cholesteatoma) disease.
Intratemporal (extracranial):
- Mastoiditis / coalescent mastoiditis
- Facial nerve palsy (LMN, eroded fallopian canal in the tympanic segment)
- Labyrinthitis / labyrinthine (lateral SCC) fistula → vertigo, SNHL, positive fistula test
- Petrositis → Gradenigo syndrome: the triad of (1) otorrhoea, (2) retro-orbital pain (V1 trigeminal), (3) lateral rectus palsy (VI nerve) from petrous apex infection.
- Subperiosteal abscess (postauricular = mastoid; Bezold abscess = pus tracking into the neck along sternocleidomastoid; Luc/Citelli abscess are other named variants).
Intracranial (life-threatening):
- Extradural abscess (commonest intracranial complication)
- Lateral / sigmoid sinus thrombophlebitis — Griesinger sign (oedema over mastoid emissary vein), picket-fence fever, Tobey-Ayer test positive.
- Meningitis (commonest cause of death in CSOM complications)
- Brain abscess — temporal lobe (commonest from ear) and cerebellar abscess.
- Otitic hydrocephalus
High-yield mnemonic — "2 M's, B's, and the rest" for complications: Mastoiditis, Meningitis, Brain abscess, Bezold abscess, lateral Sinus thrombosis, Labyrinthitis, Facial palsy, Petrositis (Gradenigo), Extradural abscess.
High-yield: Meningitis = commonest cause of death; Temporal lobe = commonest site of otogenic brain abscess; Extradural abscess = commonest intracranial complication. Reservoir sign / pulsation can accompany sinus involvement.
Key Differentials
| Condition | Distinguishing pointer |
|---|---|
| Chronic otitis externa | Discharge but intact TM, pain on tragal pressure, canal oedema, no conductive hearing loss from perforation |
| Otomycosis | Itching, "wet newspaper"/black-white fungal debris (Aspergillus, Candida), intact TM |
| Tuberculous otitis media | Multiple perforations, pale granulations, painless profuse discharge, early facial palsy, mixed hearing loss disproportionate to disease |
| Carcinoma of middle ear | Elderly, long-standing CSOM with new bleeding, severe pain, facial palsy; biopsy of unhealthy granulation |
| Wegener's / granulomatous disease | Crusting, systemic features, ANCA positive |
| Congenital cholesteatoma | White retrotympanic mass, intact TM, no discharge history |
| Glomus tumour | Pulsatile red mass behind TM, pulsatile tinnitus, rising sun appearance, Brown sign |
High-yield: A CSOM that suddenly becomes painful, bleeds, and develops facial palsy in an elderly patient → suspect malignancy (SCC) of the middle ear — biopsy mandatory.
Recently asked / exam angle
- Image-based otoscopy: identify attic perforation / white keratin debris → cholesteatoma → unsafe CSOM and choose modified radical mastoidectomy.
- Single-best: "Commonest organism in CSOM" → Pseudomonas aeruginosa.
- Investigation of choice for cholesteatoma extent → HRCT temporal bone; for residual/recurrent cholesteatoma → DW-MRI.
- Drug-related: which ear drop is safe with a perforated TM → ciprofloxacin (avoid aminoglycosides — ototoxic).
- Gradenigo syndrome triad and petrous apex localisation frequently asked.
- Eponym matching: Griesinger sign (lateral sinus thrombosis), Tobey-Ayer test, Bezold abscess (SCM), Brown sign / rising sun (glomus — distractor).
- Theory MCQ: most accepted theory of acquired cholesteatoma → retraction pocket (invagination) theory.
- Concept trap: "cholesteatoma hearer" — better-than-expected hearing because the sac bridges an eroded ossicular chain.
- Principle: in unsafe disease, eradication of disease > hearing restoration.
- Scutum erosion = earliest HRCT sign of attic cholesteatoma.
Rapid revision
- Central perforation = safe (tubotympanic); attic/marginal = unsafe (atticoantral).
- Cholesteatoma is keratinising squamous epithelium ("skin in wrong place"), erodes bone by enzymes + pressure — not malignant.
- Pseudomonas aeruginosa = commonest organism in the chronically discharging ear.
- Safe discharge = profuse, mucoid, odourless; unsafe = scanty, foul, blood-stained.
- Hearing loss in CSOM is conductive (may turn mixed/SNHL with cochlear/labyrinthine involvement).
- Topical ciprofloxacin is drug of choice; avoid aminoglycoside drops through a perforation (ototoxic).
- HRCT temporal bone = investigation of choice for unsafe disease; DW-MRI for residual/recurrent cholesteatoma.
- Tympanoplasty/myringoplasty for safe disease; mastoidectomy (CWD = modified radical/radical) for unsafe.
- Most accepted theory of acquired cholesteatoma = retraction pocket (invagination); congenital cholesteatoma = white mass behind intact TM.
- Gradenigo syndrome = otorrhoea + retro-orbital pain (V) + lateral rectus palsy (VI) from petrositis.
- Intracranial: meningitis = commonest cause of death; temporal lobe abscess = commonest otogenic brain abscess; extradural abscess = commonest intracranial complication.
- New pain, bleeding, facial palsy in long-standing CSOM (elderly) → rule out middle-ear carcinoma; never blindly avulse an attic aural polyp.