Acute Otitis Media

Acute otitis media (AOM) is an acute suppurative inflammation of the middle ear cleft (Eustachian tube → tympanic cavity → aditus → antrum → mastoid air cells), lasting under 3 weeks. It is overwhelmingly a disease of childhood, driven by Eustachian tube dysfunction, and remains a favourite NEET PG topic for its tidy four-stage evolution and its dreaded complications.

Definition & basic terminology

• Acute suppurative otitis media (ASOM/AOM): acute pyogenic infection of the middle ear cleft with pus formation, lasting <3 weeks.
• Otitis media with effusion (OME) / serous otitis media / glue ear: middle-ear fluid without acute signs of infection; the great mimic and the great differential.
• Recurrent AOM: ≥3 episodes in 6 months OR ≥4 episodes in 12 months.
• Chronic suppurative otitis media (CSOM): persistent discharge through a perforation for >3 months (the sequel of neglected/unresolved AOM).

High-yield: The middle ear cleft is lined by respiratory mucosa continuous with the nasopharynx via the Eustachian tube — which is why upper respiratory tract infections (URTIs) are the commonest precipitant of AOM.

Why children? — Eustachian tube anatomy

The paediatric Eustachian (pharyngotympanic) tube is shorter, wider, and more horizontal than the adult tube, allowing easy reflux of nasopharyngeal secretions and organisms into the middle ear. The adult tube runs at ~45° to the horizontal; the infant tube at ~10°. This single anatomical fact explains the peak incidence at 6–18 months and a second smaller peak at school entry (~5 years).

Predisposing factors:

Factor	Mechanism
Recurrent URTI / adenoid hypertrophy	Tubal obstruction + organism reservoir
Cleft palate	Tensor veli palatini dysfunction → tube won't open
Down syndrome	Hypotonia + abnormal tube
Bottle-feeding supine, passive smoking	Reflux + mucosal irritation
Allergic rhinitis, sinusitis	Mucosal oedema, tubal block
Bottle/pacifier use, day-care attendance	Increased exposure

Etiology — causative organisms

The classic NEET-tested triad (in order of frequency):

1. Streptococcus pneumoniae — commonest overall.
2. Haemophilus influenzae (mostly non-typeable).
3. Moraxella catarrhalis.

High-yield: Order to memorise — Strep pneumoniae > H. influenzae > Moraxella catarrhalis. Mnemonic: "Some Have More" (Strep, Haemophilus, Moraxella).

• In neonates, suspect Gram-negative bacilli (E. coli, Klebsiella) and Staphylococcus aureus.
• Streptococcus pyogenes (Group A Strep) classically causes a more aggressive necrotic otitis with early, large perforation.
• Viruses (RSV, rhinovirus, influenza) initiate the process by causing the preceding URTI; many early effusions are viral.

Pathophysiology — the four stages

AOM evolves through a predictable sequence. Each stage has a characteristic otoscopic picture and management implication — this is the single most-tested part of the topic.

Stage 1 — Hyperaemia (tubal occlusion): Eustachian tube obstruction → negative middle-ear pressure → retraction of the tympanic membrane (TM). Mucosa becomes congested. Otoscopy: cartwheel/radial congestion along the handle of malleus and at the periphery; landmarks still visible. Earache begins.

Stage 2 — Exudation (pre-suppuration): Exudate (serous → purulent) collects. TM becomes red and bulging, landmarks (handle of malleus, cone of light) are lost. Throbbing pain, high fever, conductive hearing loss. This is the stage of maximal systemic upset.

Stage 3 — Suppuration (perforation): Pus under tension causes pressure necrosis of the TM (classically the antero-inferior pars tensa) → spontaneous perforation with mucopurulent, often pulsatile, discharge. Dramatic relief of pain and fever once the ear discharges.

Stage 4 — Resolution / Complication: With prompt treatment, discharge ceases, the perforation heals, hearing returns. If neglected → coalescent mastoiditis, CSOM, or intracranial complication.

Flow of untreated disease:

Tubal block → negative pressure & retraction → effusion & bulging TM → pressure necrosis & perforation → resolution OR complication (mastoiditis / CSOM / intracranial)

Stage	TM appearance	Hallmark symptom
1 Hyperaemia	Cartwheel congestion, retracted, landmarks seen	Mild earache, blocked feel
2 Exudation	Red, bulging, landmarks lost	Severe throbbing pain, high fever
3 Suppuration	Perforation (antero-inferior), pulsatile discharge	Sudden relief of pain after discharge
4 Resolution	Perforation heals, mucosa normalises	Recovery; or signs of complication

High-yield: Sudden relief of severe earache with onset of ear discharge = spontaneous perforation (transition from stage 2 → 3). A bulging TM with lost landmarks = stage of exudation and is the classic indication to consider myringotomy.

Clinical features

In older children / adults:

• Earache (otalgia): deep, throbbing, worse on lying down.
• Hearing loss: conductive type.
• Ear discharge: appears after perforation; initially blood-tinged then mucopurulent.
• Fever, malaise, tinnitus, sense of fullness.
• Tenderness over the tragus is usually absent (distinguishes from otitis externa).

In infants (cannot localise pain): irritability, incessant crying, ear-tugging/rubbing, refusal to feed, vomiting/diarrhoea, fever, sleep disturbance. AOM must be excluded in any febrile infant.

High-yield: In neonates and infants, otorrhoea or non-specific systemic signs may be the only clues — always examine the TM in a crying febrile baby.

Diagnosis & investigations

AOM is a clinical diagnosis based on otoscopy (ideally pneumatic otoscopy). The American Academy of Pediatrics (AAP) requires:

1. Acute onset of symptoms, AND
2. Middle-ear effusion (bulging TM, reduced/absent TM mobility on pneumatic otoscopy, air-fluid level, or otorrhoea), AND
3. Signs of middle-ear inflammation (distinct TM erythema OR distinct otalgia).

High-yield: A bulging tympanic membrane is the single most reliable otoscopic sign of AOM. Pneumatic otoscopy (showing reduced TM mobility) is the investigation of choice to confirm a middle-ear effusion.

Supportive / specialised tests:

• Tympanometry: Type B (flat) curve = middle-ear effusion; Type C = retracted TM / negative pressure (tubal dysfunction).
• Tuning fork tests / pure tone audiometry: conductive hearing loss (Rinne negative, Weber lateralised to affected ear), air-bone gap.
• Tympanocentesis (diagnostic myringotomy with culture): reserved for neonates, immunocompromised, treatment failure, or suppurative complications — gives the organism.
• HRCT temporal bone: when mastoiditis or intracranial complication is suspected (clouding/coalescence of air cells, loss of bony septa).

Management — drug of choice & approach

The cornerstones are systemic antibiotics, analgesia, decongestants, and — when indicated — myringotomy.

Antibiotic of choice: Amoxicillin, high-dose, oral, for 5–10 days.

• High-dose amoxicillin 80–90 mg/kg/day is first-line to overcome intermediate-resistance pneumococci.
• If no response in 48–72 h, recent antibiotics, or concurrent conjunctivitis (β-lactamase producers) → amoxicillin–clavulanate (co-amoxiclav).
• Penicillin allergy → macrolide (azithromycin/clarithromycin) or cephalosporins (cefuroxime, ceftriaxone).

Adjuncts:

• Analgesics/antipyretics: paracetamol (first choice), ibuprofen.
• Nasal decongestants (xylometazoline/oxymetazoline drops) and oral pseudoephedrine to relieve tubal oedema.
• Treat the underlying cause: nasal/sinus infection, adenoids.

Watchful waiting (observation, 48–72 h): An option in otherwise healthy children >2 years with mild, unilateral AOM and no otorrhoea — give analgesia and review, since many resolve spontaneously. Children <6 months always get antibiotics; <2 years with bilateral disease or otorrhoea get antibiotics.

Myringotomy — surgical incision of the TM (classically postero-inferior quadrant, radial incision) to drain pus.

High-yield: Indications for myringotomy in AOM — (1) bulging TM with severe persistent pain, (2) incomplete resolution despite adequate antibiotics, (3) impending/early complication (e.g. mastoiditis, facial palsy), (4) AOM in immunocompromised/neonates needing culture.

Grommet (ventilation tube) insertion is the treatment for recurrent AOM and persistent OME (effusion >3 months with hearing loss), not for a single acute episode.

Scenario	Action
Child <6 months, any AOM	Antibiotics
Child <2 yr, bilateral/otorrhoea	Antibiotics
Child >2 yr, mild unilateral	Watchful waiting 48–72 h
Bulging TM + severe pain	Myringotomy + antibiotics
≥3 episodes/6 mo or ≥4/12 mo	Grommet ± adenoidectomy

Complications

Conventionally divided into intratemporal and intracranial — and "acute coalescent mastoiditis" is the bridge between them.

Intratemporal:

• Acute mastoiditis / coalescent mastoiditis — commonest complication; infection breaks down the bony septa of air cells. Signs: post-auricular swelling, redness and tenderness over mastoid, pinna pushed forward, downward and outward, sagging of postero-superior meatal wall.
• Facial nerve palsy (LMN, may occur with dehiscent facial canal).
• Labyrinthitis (vertigo, sensorineural hearing loss).
• Petrositis → Gradenigo syndrome.
• TM perforation → CSOM, tympanosclerosis, ossicular necrosis.

Intracranial (more dangerous):

• Meningitis (commonest intracranial complication; pneumococcus).
• Extradural / subdural abscess, brain abscess (temporal lobe & cerebellum).
• Lateral (sigmoid) sinus thrombophlebitis.
• Otitic hydrocephalus.

High-yield: Gradenigo syndrome (apical petrositis) = triad of (1) otorrhoea, (2) retro-orbital/deep ear pain (V trigeminal), (3) lateral rectus palsy / diplopia (VI abducens) — the 5th and 6th cranial nerves run through Dorello's canal near the petrous apex.

High-yield: Coalescent mastoiditis is suggested when ear discharge persists beyond 2 weeks with reappearance of pain/fever and sagging of the postero-superior meatal wall; HRCT shows loss of mastoid septa. Treatment is IV antibiotics + cortical mastoidectomy if no rapid response.

Key differentials

Condition	Distinguishing features
Otitis externa	Tragal tenderness +, pain on pinna movement, normal hearing/TM, canal swollen
OME (glue ear)	No acute pain/fever; dull retracted TM, air-fluid level, Type B tympanogram, hearing loss
Bullous myringitis	Painful haemorrhagic blebs on TM (Mycoplasma/viral); severe pain, intact middle ear
Referred otalgia	Normal ear exam; from teeth, TMJ, throat (CN V, VII, IX, X) — esp. tonsil/larynx Ca in adults
Furuncle of meatus	Localised pain, tender swelling in outer cartilaginous canal, normal TM
Herpes zoster oticus (Ramsay Hunt)	Vesicles on pinna/canal + facial palsy

High-yield: In an adult with persistent unilateral OME/AOM-like effusion, always exclude a nasopharyngeal carcinoma obstructing the Eustachian tube — examine the nasopharynx.

Recently asked / exam angle

• Stage-based otoscopy match: "Loss of cone of light + bulging red TM" → stage of exudation; "cartwheel appearance" → hyperaemia.
• Commonest organism of AOM → Streptococcus pneumoniae; commonest in CSOM tubotympanic → Pseudomonas (don't confuse the two).
• Drug of choice for AOM → high-dose amoxicillin; with conjunctivitis → co-amoxiclav (β-lactamase H. influenzae).
• Site of spontaneous perforation → antero-inferior pars tensa; site of surgical myringotomy → postero-inferior quadrant.
• Investigation of choice to confirm effusion → pneumatic otoscopy; Type B tympanogram.
• Gradenigo syndrome triad and which cranial nerves (V and VI) — repeatedly asked.
• Commonest complication of AOM → acute mastoiditis; commonest intracranial → meningitis.
• Why AOM is common in children → short, wide, horizontal Eustachian tube (one-liner answer).
• Pinna displacement in mastoiditis → pushed forward, downward and outward (vs. furuncle pushing it only outward/forward).
• Indications for grommet vs. myringotomy — recurrent AOM/persistent OME = grommet.

Rapid revision

1. AOM = acute suppurative inflammation of middle ear cleft, <3 weeks; children 6–18 months peak.
2. Cause: short, wide, horizontal Eustachian tube + URTI/adenoids.
3. Organisms: S. pneumoniae > H. influenzae > Moraxella (neonates: Gram-negatives, S. aureus).
4. Four stages: hyperaemia → exudation → suppuration → resolution.
5. Bulging TM with lost landmarks = exudation stage; cartwheel congestion = hyperaemia.
6. Spontaneous perforation = antero-inferior pars tensa; pain relief follows discharge.
7. Diagnosis is clinical; pneumatic otoscopy (investigation of choice) + Type B tympanogram confirm effusion.
8. DOC = high-dose amoxicillin; co-amoxiclav if resistant/with conjunctivitis; paracetamol for pain.
9. Watchful waiting OK in healthy child >2 yr with mild unilateral AOM; <6 months always treat.
10. Myringotomy (postero-inferior quadrant) for bulging painful TM, non-resolution, or complications.
11. Commonest complication = acute (coalescent) mastoiditis; commonest intracranial = meningitis.
12. Gradenigo syndrome = otorrhoea + retro-orbital pain (V) + lateral rectus palsy (VI), from apical petrositis.