GP - Otitis externa

Question 1

What is otitis externa (also known as ‘Swimmer’s ears’)?

Answer 1

Inflammation and infection of the external ear canal

Question 2

What are the 3 types of otitis externa?

Answer 2

Types:

• Localised otitis externa - infection of a hair follicle (folliculitis) that can become a boil in the ear canal
• Diffuse otitis externa (swimmer’s ear) - inflammation of the skin and subdermis of the external ear canal, which can extend to involve the outer ear and the eardrum
• Malignant otitis externa (necrotising otitis externa) - mainly affects those who are immunocompromised (HIV/ AIDS, chemotherapy, long-term steroids, renal failure) including elderly and those with diabetes mellitus. It occurs when otitis externa spreads into the bone surrounding the ear canal (the mastoid and temporal bones)
  
  • It’s common in those with diabetes –> so CHECK BLOOD GLUCOSE!

Question 3

What are the duration for acute otitis externa and chronic otitis externa respectively?

Answer 3

Acute otitis externa is < 3 weeks

Chronic otitis externa is > 3 months

Question 4

What are the causes of acute otitis externa?

Answer 4

• Bacterial (most common) - pseudomonas aeruginosa, staphylococcus aureus
• Fungal - aspergillus, candida albicans

Question 5

What are the causes of chronic otitis externa?

Answer 5

• Contact dermatitis
• Seborrhoeic dermatitis

(Most causes of chronic otitis externa are NON-BACTERIAL)

Question 6

Name 3 complications of otitis externa

Answer 6

1. Malignant otitis externa –> temporal bone osteomyelitis
2. Eardrum perforation
3. Fibrosis of ear canal causing stenosis and conductive hearing loss

Question 7

What are the presentations for acute otitis externa?

Answer 7

Presentations:

Symptoms

• Ear pain disproportionate to the size of lesion
• Pain is worse on palpation of the pinna or when an otoscope is inserted
• Itch
• Purulent ear discharge
• Conductive hearing loss if the swelling blocks the ear canal or discharge present
• Tenderness on moving jaw

Signs/ otoscopy findings

• Red, swollen, ear canal + scaly skin
• Golden crust around ear (if caused by Staphylococcus aureus)
• Inflamed eardrum

Question 8

What is malignant otitis externa?

Which organism causes this?

Answer 8

a) . A very aggressive infection mainly seen in diabetics and immunocompromised individuals where the infection spreads from the soft tissues of the ear to the bones (temporal bone and mastoid) –> temporal bone osteomyelitis
b) . Pseudomonas aeruginosa

Question 9

What are the presentations of malignant otitis externa?

Answer 9

Presentations:

Symptoms

• Severe, deep-seated ear pain that radiates to the TMJ and is worse at night time (nocturnal pain)
• Chronic purulent ear discharge (otorrhoea)
• Temporal headaches
• Hearing loss, tinnitus
• Vertigo
• Fever > 39 degree celsius
• Facial nerve palsy
• Not responding to Abx ear drops
• Hx of diabetes/ immunosuppression

Signs/ otoscopy findings

• Granulation tissue at bone-cartilage junction of the ear canal
• Purulent ear discharge

Question 10

What advice would you give to the patient with otitis externa?

Answer 10

Advice:

• Avoid damage to the external ear canal e.g. avoid using cotton buds to clean the ear canal
• Keep ears clean and dry by using ear plugs or a tight fitting cap when swimming
  
  • Avoid doing water sports for at least 7 days if acute otitis externa
• Use a hair dryer to dry the ear canal after washing hair, bathing or swimming
• Keeping shampoo, soap and water out of the ear when bathing and showering

Question 11

How do you manage patients with acute otitis externa?

Answer 11

Mx:

• Aural toilet (syringing or irrigation) + analgesia (paracetamol/ ibuprofen) + application of local heat e.g. a warm flannel
• Antibacterial
  
  • 1st line - Topical acetic acid (EarCalm spray) in primary care according to the LMSG antimicrobial guideline, or topical Abx eardrops e.g. gentamicin in secondary care according to ENT workbook. Passmed says you can give topical ciprofloxacin +/- steroid (e.g. dexamethasone)
    
    • If the tympanic membrane is perforated, avoid using aminoglycosides (gentamicin) due to ototoxicity
    • In severe infection where the canal is extensively swollen, insert an ear wick to keep the canal open and allow topical treatment to diffuse through
    • Before giving the ear drops, do microsuction of pus/ debris to enable the drops to get to the source of infection
  • 2nd line - Neomycin sulphate with corticosteroid in primary care according to the LMSG antimicrobial guideline (*confirm that the tympanic membrane is visualised and intact before prescribing)
  • If infection spreads beyond the ear canal to the pinna, neck or face, or systemic signs of infection e.g. fever, start oral Abx (flucloxacillin) and refer to exclude malignant otitis externa
• Swab any discharge in resistant cases
• Topical antifungal agents if fungal infections are suspected

Question 12

What are the referral criteria for acute otitis externa?

Answer 12

Patients should be referred to ENT if:

• If inadequate response to topical Abx
• If cellulitis spreads beyond the external ear canal
• If malignant otitis externa is suspected

Question 13

How do you investigate for malignant otitis externa?

Answer 13

CT scan!

Question 14

a) . How do you manage malignant otitis externa?
b) . What investigation would you do?

Answer 14

a). Mx:

• Non-resolving otitis externa with worsening pain –> URGENT REFERRAL TO ENT!
• IV Abx (Ciprofloxacin) to cover pseudomonal infections