Diseases of the Outer Ear: Developmental Anomalies, Trauma, Foreign Bodies, and Inflammatory Diseases

I. Anatomy Overview

II. Developmental Anomalies

Embryology

• 5 weeks' gestation: The auricle develops from the 1st (mandibular) and 2nd (hyoid) branchial arches, forming six Hillocks of His. Hillock 1 → tragus; 2 → helical crus; 3 → helix; 4 → antihelix; 5 → antitragus; 6 → lobule.
• 8 weeks: The cartilaginous outer third of the EAC forms from the 1st branchial groove; the bony inner two-thirds forms from the meatal plug.
• 21 weeks: Epithelial cells resorb to canalize the bony EAC — incomplete resorption causes atresia or stenosis.
• Postnatally, the pinna is 80% of adult size by age 5, reaching full size by age 9.

A. Preauricular Tag

• Most common ear anomaly; caused by a supernumerary hillock.
• May be associated with branchio-oto-renal (BOR) syndrome (hearing loss, branchial cleft cyst, renal anomalies).
• Treatment: elective removal.

B. Preauricular Pit

• Caused by failure of hillock fusion; most common at the helical root.
• A pit below the tragus is more likely a 1st branchial cleft anomaly.
• Also associated with BOR syndrome.
• Acute infection → antibiotics ± drainage; definitive treatment is excision of the entire tract including the cartilage base to prevent recurrence.

C. Protruding Ears

• Due to underdevelopment of the antihelix and a deep conchal bowl.
• Usually bilateral.
• Otoplasty at age 5–6: Mustarde sutures recreate the anthelical fold; Furnas sutures set back the conchal bowl.

D. Microtia

• Prevalence: 1:600–12,000; more common in males, unilateral, right side.
• Weerda classification:
  • Grade I: All components present but small; minimal extra tissue needed.
  • Grade II: Some components present (rudimentary helix); partial reconstruction.
  • Grade III: Structures present but unrecognizable (peanut ear) or anotia; total reconstruction.
• Associations: Goldenhar/hemifacial microsomia (oculo-auriculo-vertebral spectrum), Treacher Collins, BOR, CHARGE syndrome. 90% have associated hearing loss.
• Management:
  • Non-surgical: hair masking, adhesive prosthesis.
  • Bone-anchored auricular prosthesis (BAAP).
  • Surgical repair (autogenous rib — Brent 3-stage or Nagata 2-stage method; Medpore synthetic implant; irradiated rib is largely abandoned due to resorption). Timing: age 5–6 when rib is large enough.

E. Aural Atresia

• Incidence: 1:20,000; male, unilateral, right side predominance.
• Associated syndromes: Apert, Crouzon, Pfeiffer, Goldenhar, Treacher Collins, Trisomies 13/18/21.
• Assessment: Bone-conduction ABR before 4 months of age; high-resolution CT of temporal bone before surgical planning.
• Jahrsdoefer scoring (CT-based, /10) predicts surgical success — score ≥8 predicts good outcome. Key criteria: stapes present (2 pts), oval/round windows patent, middle ear space, facial nerve position, malleus-incus complex, mastoid pneumatization.
• Management:
  • Bilateral: early bone-conduction hearing aid.
  • Unilateral: air-conduction aid in the patent ear; bone-conduction aid on the atretic side.
  • Surgical: BAHA (percutaneous abutment or transcutaneous magnet) or formal atresia repair (after age 5, after microtia repair).

III. Trauma of the Outer Ear

A. Lacerations

• Simple (with or without cartilage), stellate from blunt trauma, or avulsion.
• Treatment: deep cleaning, debridement, surgical repair; consider bolster dressing to prevent hematoma.
• Complications: perichondritis, cartilage necrosis.

B. Auricular Hematoma

• Typical cause: blunt trauma (common in wrestlers/boxers → "cauliflower ear").
• Treatment: incision and drainage with through-and-through sutures and bolster dressing; systemic fluoroquinolones.
• Complications: fibrosis, cauliflower/wrestler's ear, perichondritis.

C. Frostbite

• Cold exposure causes endothelial disruption, erythrocyte extravasation, platelet aggregation, and sludging.
• Symptoms: pain, burning, discoloration, reduced pliability, sensory loss.
• Treatment: slow warming; antibiotics; anticoagulants; debridement only after demarcation. No pressure dressings.

D. Bites

• Lobe most commonly affected; human bites carry greater infection risk.
• Treatment: meticulous cleaning, systemic antibiotics, surgical repair.

E. Keloids and Hypertrophic Scars

• Higher rates in African American and Hispanic populations (up to 30%).
• Treatment: steroid injection, excision, pressure dressings, rarely radiotherapy.

IV. Foreign Bodies of the External Auditory Canal

• Common objects: insects, nuts, beans, gum, putty, beads, toys.
• Key rule: avoid irrigation — vegetable matter will expand with water; blind instrumentation risks bleeding, canal edema, or TM perforation.
• Treatment:
  • Local anesthetic block; microscopic examination and careful instrumentation.
  • Mineral oil or antibiotic solution may facilitate removal.
  • Topical antibiotics after removal if canal is irritated.

V. Inflammatory Diseases of the Outer Ear

A. Acute Otitis Externa (AOE) — "Swimmer's Ear"

• Definition: Rapid-onset (<48 hours) EAC inflammation; generally unilateral.
• ~2.4 million US healthcare visits/year; peak age 5–10 years; more common in summer.
• Predisposing factors: narrow EAC, exostoses, eczema/seborrhoea/psoriasis, hearing-aid trauma, excess wax removal, water exposure.

• Bacterial: >90% of cases — P. aeruginosa (most common), S. epidermidis, S. aureus.
• Fungal: Aspergillus, Candida (<2% primary; more common after antibiotic treatment).
• Viral (rare): varicella, measles, herpesvirus. Herpes zoster oticus (HZO) without facial palsy; Ramsay Hunt syndrome = HZO + facial palsy ± SNHL or vertigo.

• Moderate-to-severe otalgia worsened by pinna manipulation (key differentiator from mastoiditis where mastoid tip is tender).
• Pruritus, erythema, scant clear → seropurulent discharge; edema, feeling of fullness, conductive hearing loss.
• Preauricular/cervical lymphadenopathy.

• Topical therapy is first-line (oral antibiotics are not effective). Options: fluoroquinolone drops or aminoglycoside + second antibiotic. Add corticosteroid to reduce inflammation. Acetic acid (50% diluted) useful in early mild cases.
• Caution with aminoglycosides if TM integrity uncertain (ototoxicity risk); neomycin contact hypersensitivity is common.
• EAC debridement is an important adjunct. If TM not visible, place a wick (cotton, Merocel sponge, or antibiotic-impregnated gauze) to stent the canal open and allow topical delivery.
• Preventive: occlusive earplugs for swimming; avoid cotton-tipped applicators.

B. Chronic Otitis Externa (COE)

• Bilateral in >50% of patients; affects 3–5% of the population.
• Mechanisms:
  • Allergic: contact dermatitis from neomycin, hair sprays, hearing-aid molds.
  • Systemic: amyloidosis, sarcoidosis, granulomatosis with polyangiitis, Sjögren's, psoriasis, lichen planus.
  • Chronic infection: granular OE from bacteria/fungi causing granulation and excoriation of the canal.
  • Local factors: moisture, elevated pH.
• Signs: Pruritus, mild discomfort, aural fullness; secretory (wet) or squamous (dry) types; atrophy and stenosis of canal skin (Fig. 138.1 in Cummings).
• Fungal OE (otomycosis): Severe pruritus, clear drainage, "cotton-like" debris. Candida: white plug. Aspergillus: moist white plug with black debris ("wet newspaper") — more aggressive infection of epithelial/subcutaneous tissues.
• Treatment: Dry ear precautions; meticulous EAC cleaning under microscopy; topical antibiotics long-term; for fungal OE: topical antifungals (e.g., clotrimazole 1%), EAC acidification. High recurrence rate.
• Severe COE may result in postinflammatory medial canal fibrosis — blind-ending canal.

Chronic external otitis: atrophy and stenosis of the canal skin — Cummings Otolaryngology, Fig. 138.1

Otomycosis with Aspergillus flavus: tufts of fungus crowned by white conidiophores — Cummings Otolaryngology, Fig. 138.2

C. Other EAC Conditions

VI. Complications of Otitis Externa

Perichondritis / Chondritis

• Extension of infection into auricular cartilage; can follow trauma, AOE, ear piercing.
• Presents as red, hot, swollen, painful auricle (sparing the lobule, which lacks cartilage).
• Causative organism: P. aeruginosa.
• Treatment: fluoroquinolones (systemic); may require surgical drainage.

Malignant (Necrotizing) Otitis Externa (MOE/NOE)

• Most feared complication — aggressive osteomyelitis of the EAC, mastoid, and skull base.
• Pathophysiology: Microangiopathy (especially in diabetics) and elevated cerumen pH allow bacterial invasion → vascular thrombosis → coagulative tissue necrosis. Spreads via fissures of Santorini and the tympanomastoid suture to the stylomastoid and jugular foramina. Does NOT spread through pneumatized tracts; middle ear is spared until late.
• Risk factors: Diabetes mellitus (up to 90% of cases), HIV/AIDS, myeloid malignancies, immunosuppression. Rare in immunocompetent patients.
• Causative organism: P. aeruginosa in >90%; also S. aureus, S. epidermidis, Proteus mirabilis, fungi (esp. Aspergillus fumigatus in HIV+).
• Mortality: 5–20% even in the antibiotic era.

• Severe, deep-seated otalgia out of proportion to examination findings, worse at night.
• Otorrhoea, EAC edema.
• Pathognomonic: granulation tissue at the bony-cartilaginous junction (isthmus) of the EAC.
• Cranial nerve palsies (CN VII–XII): CN VII most commonly affected (stylomastoid foramen). Multiple CN deficits = worse prognosis.
• "Picket-fence" spiking fevers with septic thrombophlebitis of the sigmoid sinus.
• Meningeal signs when intracranial spread occurs.

MOE: Granulation tissue at the bony-cartilaginous junction — Cummings Otolaryngology, Fig. 138.3

• Biopsy granulation tissue — mandatory to exclude squamous cell carcinoma (identical presentation).
• ESR: markedly elevated (nonspecific; used to monitor treatment response and recurrence).
• Bacterial and fungal cultures.
• Imaging:
  • CT (first-line): cortical bone erosion, soft-tissue abnormalities around EAC/skull base. Limited for monitoring response (bony changes persist after cure).
  • MRI: superior for soft tissue/dural involvement; useful for follow-up.
  • Tc-99m bone scan (SPECT): imaging of choice for confirming diagnosis; detects osteoblastic activity before CT shows changes. Cannot distinguish infection from malignancy. Not used for follow-up (remains positive after cure).
  • Gallium-67 or In-111 leukocyte scan: shows inflammatory activity; normalizes with treatment — preferred for monitoring response (every 4 weeks).

• Multidisciplinary: otolaryngology, endocrinology, infectious disease, radiology, microbiology.
• Culture-directed, antipseudomonal coverage. Early disease: oral fluoroquinolone (ciprofloxacin). Advanced disease: IV antipseudomonal antibiotics for 6–8 weeks.
• Note: Fluoroquinolone-resistant Pseudomonas is an increasing concern — fluoroquinolones are the only oral agents with antipseudomonal activity.
• Strict glycaemic control in diabetics.
• Surgery: debridement of necrotic tissue; rarely extensive skull base surgery for unresponsive disease.

Summary Table