The External Ear

General Compartments

• External

• Middle

• Inner

External Ear

• Consists of:

1. Auricle / Pinna: yellow elastic cartilage except the lobule.

2. External Auditory Canal: • 24mm in length

• S – shaped (not straight)

• 2 parts: • Cartilaginous Part: outer 1/3, skin contains ceruminous and

pilosebaceous glands which secret wax, and hair follicles.

• Bony Part: inner 2/3, skin is thin and continuous with outer layer of tympanic membrane.

External Ear (continued)

3. Tympanic Membrane: • Oblique, oval

• 9-10 mm tall, 8-9 mm wide, 0.1 mm thick.

• Layers: 3 layers • Outer epithelial layer: continuous with the skin lining the ear

canal

• Inner mucosal layer: continuous with the mucosa of the middle ear.

• Middle fibrous layer: more well- formed and organized in pars tensa.

• 2 parts: • Pars Tensa: most of TM, periphery is thickened to form the

annulus.

• Pars Flaccida: above the lateral process of malleus

Cerumen

• consists of desquamated epithelium mixed with the sebum produced from sebaceous glands and the watery secretions of modified apocrine sweat glands (apopilo-sebaceous unit)

• acidic: bacteriostatic + fungostatic

• contains lysozymes which are bactericidal

Nerve Supply

• Anterior part: Auriculotemporal branch of mandibular branch of trigeminal (V)

• Posterior and central part: auricular branch of Vagus Nerve (X), Facial nerve (VII)

• Posterior and inferior part: cervical C2, C3

• Understanding innervation is important to understand referred ear pain

External ear

Embryology:

• Condensation of the mesoderm of the 1st and 2nd pharyngeal/brachial arches occurs to give rise to 6 hillocks of His

• 20th week gestation: It has reached adult shape

• 9 years: reach adult size (this is the age of performing plastic surgery)

Congenintal anomalies of the Pinna

• Preauricular tag • Remnant of one of the hillocks.

• Uncertain risk factor for hearing loss.

• Preauricular sinus • results from improper fusion of the 1st & 2nd brachial arches

• May be associated with branchio-oto-renal syndrome

• Surgery is only indicated when it is complicated by recurrent infection or abscesses

• Microtia: underdeveloped ear pinna

• Bat ears: protruding ears, loss of antihelix

Preauricular Tag

Trauma to the Auricle

• Haematoma of the Auricle: • Collection of blood between the

cartilage and its perichondrium.

• A result of blunt trauma, e.g. boxers, wrestlers.

• Extravasated blood may clot and organize resulting in “Cauliflower Ear” or “Boxers Ear”

• Treatment: either repeated aspiration under aseptic precautions with pressure dressing or incision and drainage with pressure dressing and prophylactic antibiotics.

Haematoma Cauliflower ear

Infections of the auricle

• Erysipelas: • infection of the overlying skin • Caused by group A beta hemolytic strep. • Rapid treatment with oral or IV antibiotic

• cellulitis (infection of the soft tissue) • Cellulitis of the ear typically results from a spreading otitis externa or a

penetrating injury. • It is distinguished from perichondritis by the lack of induration • Rapid treatment with Anti-staph oral or IV antibiotic

• Perichondiritis to chondritis : • represent infections of the auricular perichondrium or cartilage • Secondary to lacerations, haematoma, surgical incisions or piercings. Or as an

extension from diffuse otitis externa. • infection involving the cartilage itself of the auricle & external auditory canal. • The lobule, which contains no cartilage, is spared • Most common cause is Pseudomonas aeruginosa and mixed flora. • Treament: systemic and local antibiotics. In case of abscess formation, it must

be drained promptly and treated with systemic and local antobiotics.

Relapsing Polychondritis

• Auto-immune disease

• Other cartilages may be involved like septal, laryngeal, tracheal and costal cartilages.

• presentation: • acute phase: fever

• sudden sever painful uniform swelling and erythema of the auricle

• Chondritis rapidly develops and resolves in 5-10 days

• Spares: external auditory canal, lobule

Inflammations of Ear Canal

External auditory canal infections

• Furunculosis • Furuncle is a localized abscess of the

apopilo-sebaceous unit

• Most common organism: Staph aureus.

• Confined to the outer 1/3 of the ear canal.

• Symptoms: severe pain and tenderness.

• Treatment: • Analgesia

• Anti-staphylococcal oral and topical antibiotics should be administered.

• A fluctuant lesion should be incised and drained under local anesthetic.

Otitis externa • Diffuse swelling of the meatal skin which may spread to the

pinna and epidermal layer of the tympanic membrane.

• Approximately 80% of cases occur in the summer, particularly in warm, humid environments.

• Other predisposing factors include anatomic obstructions of the ear canal (e.g., stenosis, impacted cerumen), hearing aid or ear plug use, self-induced trauma (e.g., by cotton swabs), and swimming, secondary to chronic middle ear discharge.

• Common pathogens: Staph aureus, Pseudomonas pyocyaneus, Bacillis proteus, E coli but more often the infection is mixed.

• Symptoms: hot, burning sensation in the ear, pain, discharge, inflamed swollen meatal skin.

Treatment : 1. Frequent aural toileting 2. Local and systemic antibiotics 3. Medicated ear wicks/packs 4. Analgesics 5. Avoid water contact

Fungal otitis externa (otomycosis) • Aspergillus accounts for 80-90 % of cases with

Candida being responsible for the remaining 10-20%.

• In hot, humid climates.

• Secondary fungal growth is also seen in patients using topical antibiotics for treatment of otitis externa or middle ear suppuration.

• Presentation: intense itching, discomfort or pain in the ear, watery discharge with a musty odour and ear blockage. The fungal mass may appear white, brown or black and has been likened to a wet piece of filter paper.

Treatment :

1. Frequent aural toileting

2. Local antifungal

3. Avoid water contact

Aspergillus

Candida

Malignant (Necrotizing) otitis externa • Malignant Otitis Externa: otitis externa + osteomyelitis of the

tympanic plate of the temporal bone which may extend to involve skull base

• Clinical Presentation: • Persistent Otalgia more than 1 month • Persistent Otorrhea with granulation tissue • Persistent Otorrhea in the immunocompromised patients

(Diabetics with microangiopathy and cellular immune dysfunction), HIV.

• Deep-seated aural pain (pain out of proportion to examination findings).

• Facial nerve palsy and multiple lower cranial nerves palsy.

• Most cases are caused by P. aeruginosa

• Diagnostic: • CT scan with IV contrast • MRI • Gallium-67 and Technetium-99m bone scanning

Malignant (Necrotizing) otitis externa

Treatment: • Regular aural toilet • Blood sugar control • Correct immunodeficiency if possible • Pain killer • Infectious disease consult • IV antibiotic for 6-8 weeks, with anti-

pseudomonal coverage (gentamicin+ticarcillin or ceftazidime+aminoglycoside or quinolones like ciprofloxacin)

Prognosis: • Mortality is 5-20%

Herpes Zoster Oticus • prodrome of otalgia, which may be severe.

• A vesicular eruption is seen in the canal and concha.

• Ultimately, these vesicles rupture and form crusts.

• Etiology:

• After primary infection (chickenpox), varicella-zoster virus is harbored in a latent state in sensory ganglia, and reactivates with infection spreading along dermatomes.

• Harbored in the facial nerve VII and the vestibular ganglia of VIII

• A subgroup of patients manifest Ramsay Hunt syndrome: SNHL, tinnitus or vertigo or both, Palsy: lower motor neuron palsy of the ipsilateral facial nerve

• 2nd commonest cause of lower facial nerve palsy after bell's palsy (9%)

• Prognosis for facial nerve recovery worse than Bell’s palsy (only 60% regain normal function, where as up 90% regain normal function in bell’s palsy).

• Symptoms:

• Auricular pain: the 1st symptom to appear

• Vesicular Rash: location: concha, EAC, mucosa of the palate, anterior 2/3 of the tongue

• Treatment:

• acyclovir or valacyclovir

• High-dose steroids

• Corneal protection