DISEASES OF THE EXTERNAL EAR (AB) Flashcards
What structures make up the outer ear?
Auricle and external auditory canal (EAC), up to the tympanic membrane.
What type of epithelium lines the external auditory canal?
Keratinized stratified squamous epithelium.
How long is the external auditory canal (EAC)?
Approximately 2.5 cm.
What marks the demarcation between the external and inner ear?
The tympanic membrane.
What is the composition of the auricle?
Mostly skin-lined cartilage.
What is the composition of the external auditory meatus?
40% cartilaginous (lateral 1/3), 60% bony (medial 2/3).
How does the skin differ in the cartilaginous and bony portions of the EAC?
Cartilaginous portion has thicker skin with a soft dermal layer; bony portion has thicker skin (1/2 to 1 mm).
What shape is the external auditory canal (EAC)?
S-shaped.
How should the ear be pulled to straighten the EAC in adults?
Backward, upward, and outward.
How should the ear be pulled to straighten the EAC in infants?
Backward and downward.
Where is the narrowest portion of the external auditory canal?
At the bony-cartilage junction, called the isthmus of the EAC.
What cranial nerves provide innervation to the external ear?
Cranial nerves V, VII, IX, and X.
What arteries supply the external ear?
Superficial temporal, posterior auricular, and deep auricular branches.
How does venous drainage of the external ear occur?
Through the superficial temporal and posterior auricular veins.
What is the most common cause of impacted cerumen?
Use of Q-tips.
What is the criterion for diagnosing impacted cerumen?
Cerumen must occlude the entire lumen of the EAC.
Where are the sebaceous and apocrine glands that produce cerumen located?
In the cartilaginous third of the external ear, where ear hairs are found.
What are two types of cerumen?
Wet and dry.
What methods are used to remove impacted cerumen?
Curette under direct visualization, thin suction tip, or water irrigation if the tympanic membrane is intact.
Why should irrigation be avoided in some cases of impacted cerumen?
If a foreign body is present, irrigation could push it deeper, causing complications.
When should cerumen not be irrigated?
When the tympanic membrane is perforated.
What substances can be used to soften cerumen?
Cerumenolytics (docusate sodium, paradichlorobenzene), oil, hydrogen peroxide.
What are the primary causes of trauma to the external ear?
Lacerations, hematomas, burns, frostbite, cellulitis, and perichondritis.
What is the difference between lacerations and incised wounds?
Lacerations have clean edges from blunt trauma, incised wounds are from sharp objects.
What is the recommended treatment for lacerations of the external ear?
Thorough wound cleaning, skin suturing (avoid perichondrium and cartilage), antibiotics, and daily wound care.
What can happen if perichondrium and cartilage are sutured?
Inflammation, necrosis, and ‘cauliflower ear’ formation.
What is the main cause of hematomas in the external ear?
Blunt trauma, commonly seen in wrestlers, boxers, and victims of abuse.
Why does the cartilage of the ear need special care in hematomas?
It is avascular, aneural, and alymphatic, relying on the overlying skin for nourishment.
What is the consequence of an untreated auricular hematoma?
Cauliflower ear.
What is the treatment for auricular hematomas?
Incision and drainage, pressure dressing, and anti-staphylococcal antibiotics (penicillin, 1st gen cephalosporins, erythromycin).
What percentage of patients with facial burns have ear burns?
0.9
What percentage of external ear burns develop suppurative chondritis?
0.25
How are first-degree burns of the external ear treated?
Conservatively.
How are second-degree burns of the external ear treated?
Silver sulfadiazine with mesh dressings.
How are third-degree burns of the external ear treated?
Extensive debridement, closure, and later grafting (preferably skin flaps).
What causes frostbite of the external ear?
Direct cellular damage and microvascular insult leading to local ischemia.
What is the initial management of frostbite of the external ear?
Rapid warming and antibiotics.
Why is surgical debridement delayed in frostbite cases?
To allow time for potentially viable tissue to recover.
What is perichondritis?
Infection of the perichondrium or cartilage of the ear.
What is a common cause of perichondritis?
Trauma to the auricle.
What are symptoms of perichondritis?
Pain over the auricle and deep in the canal, pruritus, induration, edema.
How is perichondritis treated?
Antibiotics.
What are common foreign bodies found in the external auditory canal?
Any object that fits into the opening of the EAC.
Why is visualization mandatory before removing a foreign body from the EAC?
To assess the location and avoid complications.
What should be done after removing a foreign body from the EAC?
Reassess for abrasions, lacerations, or a punctured tympanic membrane; administer topical antibiotics and steroids to prevent reactive edema.
When might sedation or general anesthesia be required for foreign body removal?
If the patient is uncooperative.
What is one of the most common diseases of the ear?
Otitis externa
What are the possible causes of otitis externa?
Infectious or non-infectious causes
What are the predisposing factors for otitis externa?
Change in pH, environmental changes, mild trauma
What are the principles of therapy for otitis externa?
Relief of pain, eliminating predisposing factors, thorough cleaning
What is furunculosis?
Infection of the outer third of the external auditory canal (EAC) affecting pilosebaceous follicles
What are the common pathogens causing furunculosis?
Staphylococcus aureus or Staphylococcus albus
What is the best treatment option for furunculosis?
Incision and drainage, systemic antibiotics, and analgesics
What is another name for diffuse otitis externa?
Swimmer’s ear
What organism commonly causes diffuse otitis externa?
Pseudomonas species and viruses
When is diffuse otitis externa most commonly seen?
During hot, humid weather
What is the ‘otic wick’ technique?
A small gauze soaked in otic drops inserted into a swollen ear canal to facilitate medication absorption
What is the main symptom of otomycosis?
Severe pruritus
What is the most common fungal pathogen causing otomycosis?
Aspergillus niger
Why does otomycosis typically occur in the medial 2/3 of the EAC?
The outer 1/3 contains pilosebaceous units and cerumen glands, which provide natural protection
What is the initial step in treating otomycosis?
Aural toilette (removal of fungal material)
What is the first-line antifungal treatment for otomycosis?
Otic antifungal preparations for 2 weeks
What bacterial infection often follows otomycosis?
Secondary bacterial infection
What is Ramsay Hunt Syndrome?
Herpes zoster oticus caused by the reactivation of the varicella-zoster virus
What are the clinical signs of herpes zoster oticus?
Painful vesicles in the EAC and auricle following a dermatomal pattern
What nerve is commonly affected in Ramsay Hunt Syndrome?
Facial nerve (Cranial Nerve VII)
What symptom suggests facial nerve involvement in Ramsay Hunt Syndrome?
Facial nerve palsy
What is the treatment for severe cases of herpes zoster oticus?
Antivirals, symptomatic pain management, vitamin B12, and systemic steroids for facial palsy
What is Bell’s palsy associated with?
Ramsay Hunt Syndrome
What are common causes of contact dermatitis in the ear?
Earphones, ear plugs, hearing aids, fake jewelry
What is the main feature of seborrheic dermatitis?
Erythematous, raised plaque with a greasy scale
What is the causative organism of seborrheic dermatitis?
Malassezia furfur
What is the treatment for seborrheic dermatitis?
Topical steroids and/or keratolytics
What percentage of psoriasis cases involve the external ear?
0.2
What is the first-line treatment for mild psoriasis?
Topical steroids and UV phototherapy
What systemic treatments are used for severe psoriasis?
Cyclosporine or methotrexate
What is necrotizing external otitis (NEO) also known as?
Malignant otitis externa
Why is NEO considered malignant?
It is a life-threatening condition due to its potential to spread to vital structures
What is the most common risk factor for NEO?
Diabetes or immunocompromised status
What is the primary bacterial pathogen in NEO?
Pseudomonas aeruginosa
What are the key symptoms of NEO?
Deep-seated aural pain, chronic purulent otorrhea, aural fullness
What is the treatment for NEO?
IV antibiotics for at least 4 weeks, followed by oral antibiotics and serial gallium scans
What is the key treatment step for NEO?
Removal of all necrotic and granulated tissues
What is relapsing polychondritis?
A progressive destruction of cartilage affecting the nose, ears, and larynx
What are the key features of relapsing polychondritis?
Inflamed cauliflower ear, saddle bridge deformity of the nose
What is the treatment for relapsing polychondritis?
Steroids to control acute attacks and suppress recurrences
What is erysipelas?
Acute superficial cellulitis caused by Group A beta-hemolytic streptococci
What is the hallmark feature of erysipelas?
Bright red skin with well-demarcated advancing margins
What is the treatment for erysipelas?
Rapid administration of oral or IV antibiotics
What is keratosis obturans?
Accumulation of squamous epithelium in the EAC
What age group is commonly affected by keratosis obturans?
Young individuals
What are the symptoms of keratosis obturans?
Pain, hyperemia, granulation, and occasional hearing loss
What is the treatment for keratosis obturans?
Regular debridement and topical steroids
What is canal cholesteatoma?
Cystic collection of squamous epithelium in the EAC
What is a key feature of canal cholesteatoma on examination?
Pearly white, foul-smelling, soft, and pliable mass
How does canal cholesteatoma behave clinically?
It is benign but behaves like a malignant lesion due to aggressive local destruction
What are the symptoms of canal cholesteatoma?
Unilateral pain, purulent otorrhea, bony erosion on imaging
What is the primary management for canal cholesteatoma?
Frequent debridement and topical antibiotics
When is surgery considered for canal cholesteatoma?
In complicated cases or failure of medical therapy
