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

I. Anatomy and Embryological Development

• 5 weeks' gestation: The auricle develops from the first (mandibular) and second (hyoid) branchial arches, giving rise to the six Hillocks of His. The tragus derives from the 1st hillock, helical crus from the 2nd, remainder of helix from the 3rd, antihelix from the 4th, antitragus from the 5th, and lobule from the 6th.
• 8 weeks' gestation: The cartilaginous (outer 1/3) EAC forms by invagination of the concha cavum (1st branchial groove). The bony EAC (inner 2/3) forms from invagination of the meatal plug (a solid epithelial core) to create the meatal plate.
• 21 weeks' gestation: Epithelial cells resorb to canalize the bony EAC. Incomplete resorption results in atresia or stenosis.

II. Congenital Anomalies of Development

1. Preauricular Tag

• Most common ear anomaly.
• Caused by supernumerary hillock formation.
• May be associated with branchio-oto-renal (BOR) syndrome (hearing loss, branchial cleft cyst, renal anomalies) or other craniofacial syndromes.
• Treatment: elective removal.

2. Preauricular Pit

• Likely due to failure of fusion of hillocks.
• Most commonly located at the helical root; a pit below the tragus is more likely a first branchial cleft anomaly.
• May be associated with BOR syndrome.
• Acute infection is treated with antibiotics; recurrent infections warrant surgical excision.

3. Microtia / Anotia

• Incidence: 1:8,000–10,000 live births; more commonly unilateral and right-sided.
• 60% are syndromic, associated with Goldenhar syndrome (oculo-auriculo-vertebral spectrum), Treacher Collins, BOR, Townes-Brocks, CHARGE, and others.
• 90% have associated hearing loss; facial nerve palsy may also occur.
• Weerda classification:
  • Grade I: All components present but small (≥2 SD below normal); minimal reconstruction needed.
  • Grade II: Some components present (e.g., rudimentary helix); partial reconstruction with additional skin and cartilage needed.
  • Grade III: Structures not recognizable ("peanut ear") or absent (anotia); total reconstruction required.
• Management:
  • Bone conduction ABR prior to 4 months of age.
  • Surgical options: bone-anchored auricular prosthesis (BAAP), autogenous rib graft repair (Brent or Nagata method — performed at ≥5 years of age when rib is sufficient), or synthetic implant (Medpore, usable from age 3).

4. Aural Atresia

• Incidence: 1:20,000 live births; more often male, unilateral, right-sided.
• Associated syndromes: Apert, Crouzon, Pfeiffer, Goldenhar, Treacher Collins, trisomies 13/18/21, Turner syndrome.
• Due to incomplete resorption/canalization of the meatal plug.
• Assessment: Bone conduction ABR before age 4 months; high-resolution CT of temporal bone if canal stenosis, drainage, or pit present.
• Management:
  • Unilateral: Early repair only if canal cholesteatoma; otherwise bone-anchored hearing aid (BAHA) on atretic side.
  • Bilateral: Early bone conduction hearing aid essential.
  • Atresia repair usually delayed to age ≥5 years (after microtia repair); outcome predicted by the Jahrsdoefer score (≥8/10 predicts good result): stapes present (2 pts), patent oval window, round window, middle ear space, facial nerve, malleus-incus complex, mastoid pneumatization, incus-stapes connection, external ear appearance (each 1 pt).

III. Traumatic Conditions

1. Auricular Hematoma

• Typically associated with contact sports (wrestling, boxing).
• Blood accumulates between perichondrium and cartilage, separating the cartilage from its blood supply.
• If untreated → avascular necrosis → fibrocartilage deposition → "cauliflower ear" deformity.
• Treatment: Incision and drainage + compression with dental rolls (bolster dressing) for 7–14 days to prevent re-accumulation; antibiotic prophylaxis.
• If found in a non-ambulatory infant, suspect child abuse.

2. Auricular Laceration and Avulsion

• Laceration: Copious irrigation, debridement, primary closure, antibiotics; tetanus/rabies prophylaxis if indicated; bolster suture if perichondrium has been raised.
• Avulsion:
  • <1.5 cm: reattach or primary closure.

  • 1.5 cm: composite graft from contralateral ear or local flap.

  • Complete avulsion: options include microvascular reimplantation, banking of deepithelialized cartilage under the temporalis fascia for later reconstruction, or auricular prosthesis.

3. Exostoses

• Overgrowth of immature lamellar bone — strongly associated with cold water exposure ("surfer's ear").
• Bilateral, broadly based lesions in the medial half of the EAC.
• Surgical removal only if symptomatic (hearing loss, recurrent infections).

4. Osteoma

• Overgrowth of cancellous bone; distinct from exostoses.
• Unilateral, pedunculated lesion in the outer half of the EAC.
• Surgery only if symptomatic.

5. Keratosis Obturans

• Desquamation of hyperplastic epithelium leading to a dense keratin plug and EAC obstruction.
• Affects the entire circumference of the medial EAC; may widen the bony canal under pressure.
• Symptoms: otalgia and conductive hearing loss.
• Treatment: acetic acid irrigations or surgical removal; lifelong periodic debridements often necessary.

IV. Foreign Bodies of the External Auditory Canal

• Ear pain, discharge, and/or conductive hearing loss if canal becomes inflamed.
• Live insect: acute onset of severe pain with the sensation of movement in the ear.
• Diagnosis is by direct visualization with otoscopy.

• Alligator forceps for graspable objects.
• Ear curette, suction, or warm water irrigation for non-graspable objects (thread catheter posterior to foreign body, irrigate to push it out).
• Live insects must first be killed with mineral oil before removal.
• Button batteries are a hazardous emergency requiring urgent otolaryngology consultation (risk of liquefaction necrosis from electrochemical injury).

V. Inflammatory Diseases of the Outer Ear

A. Acute Otitis Externa (AOE)

• Pseudomonas aeruginosa — most common
• Staphylococcus epidermidis — second
• Staphylococcus aureus — third
• Fungal (Aspergillus, Candida) — <2%; more common following antibiotic treatment of bacterial AOE.

• Moderate to severe otalgia, worsened with pinna manipulation (key diagnostic sign).
• Pruritus, erythema, scant clear discharge (early) → seropurulent discharge, edema, conductive hearing loss (later).
• Lymphadenopathy (preauricular or cervical).
• Differentiate from mastoiditis: AOE has tragal/pinna tenderness; mastoiditis has tenderness over the mastoid tip.

B. Chronic Otitis Externa (COE)

• Allergic/contact: Reaction to neomycin (most common topical allergen), hair sprays, hearing aid molds.
• Systemic dermatoses: Psoriasis, lichen planus, seborrheic dermatitis, sarcoidosis, Wegener granulomatosis, amyloidosis.
• Chronic infection (granular OE): Bacteria, fungi, or both → granulation and excoriation of canal skin.
• Local factors: Moisture, elevated canal pH.

C. Otomycosis (Fungal OE)

• Severe pruritus; clear drainage; "cotton-like" debris filling the canal.
• Aspergillus niger — black-speckled "wet newspaper" appearance.
• Candida — white debris.
• Treatment: aural toilet, topical antifungals (clotrimazole, acetic acid).

VI. Complications of Otitis Externa

Malignant (Necrotizing) Otitis Externa — In Detail

• Diabetes mellitus (up to 90% of cases) — microangiopathy, elevated cerumen pH.
• Other immunocompromised states: HIV/AIDS, myeloid malignancies, pharmacologic immunosuppression.

• Severe, long-standing otalgia, worse at night.
• Otorrhea.
• Pathognomonic sign: granulation tissue at the bony-cartilaginous junction of the EAC floor.
• Cranial nerve palsies: CN VII (facial nerve at stylomastoid foramen) most common; CN IX–XII with progression.
• Intracranial: meningeal signs, headache, fever, altered consciousness; sigmoid sinus thrombosis → spiking "picket-fence" fevers.

• ESR — markedly elevated (follows treatment response).
• CT — cortical bone erosion, soft tissue changes adjacent to skull base; best first-line test for bony detail.
• MRI — superior for soft tissue and dural involvement; better for following treatment response.
• Technetium-99m bone scan — highly sensitive for early bony infection but cannot distinguish infection from malignancy and remains positive after resolution.
• Gallium-67 / Indium-111 leukocyte scan — normalizes with treatment; used to monitor response.
• Biopsy to exclude squamous cell carcinoma (which can mimic MOE clinically and radiologically).

• Early: oral ciprofloxacin (only enteral anti-pseudomonal).
• Advanced: IV antipseudomonal antibiotics (e.g., ceftazidime) → transition to oral fluoroquinolone; minimum 6 weeks total duration.
• Team: otolaryngologist + infectious disease + endocrinologist + diabetologist.
• Fungal MOE: IV amphotericin B; voriconazole is recommended first-line for invasive aspergillosis.
• Adjunct: hyperbaric oxygen therapy (for refractory cases or facial nerve palsy — no RCT evidence but supported by case series).
• Surgery: limited role; reserved for tissue biopsy, debridement of necrotic sequestra, or fulminant cases (wide skull-base resection with vascularized flap coverage).

Herpes Zoster Oticus (Ramsay Hunt Syndrome) — Inflammatory Complication

• Triad: Painful vesicular eruption in the EAC/auricle (herpes zoster oticus) + ipsilateral facial nerve palsy + sensorineural hearing loss/vertigo (CN VIII involvement).
• Treatment: early acyclovir/valacyclovir + corticosteroids; facial nerve prognosis worse than Bell's palsy.

Summary Table