Ear Infections

Question 1

What is otitis externa?

Answer 1

• Otitis externa is an infection of the external ear, a common condition that is mainly seen in primary care.
• Otitis externa typically affects the external auditory canal – the part of the ear via which sound waves travel to reach the tympanic membrane.
• It is more common in younger ages and females, with a prevalence of around 1%.
• The incidence tends to be higher in hot and humid climates, and towards the end of summer.

Question 2

What causes otitis externa?

Answer 2

• Bacterial
  
  • Pseudomonas aeruginosa
  • Staph aureus
• Any interruption in wax formation (e.g. repeated water exposure)
• Trauma to the canal (e.g. cotton buds)
• Blockage (e.g. debris) can disrupt the external auditory canal’s protective mechanisms, and lead to pathogen overgrowth and inflammation.

Question 3

Outline the pathophysiology of otitis externa

Answer 3

• The skin becomes erythematous, swollen, tender, and warm, leading to debris and discharge accumulation.
• The narrowing of the canal, in combination with the accumulation of debris, leads to further entrapment of pathogens and propagating the infective process.

Question 4

What are the causative organisms of otitits externa?

Answer 4

• Pseudomonas Aeruginosa (around 40%)
• S. Epidermidis
• S. Aureus
• Anaerobes
• In rarer cases, it can be due to a fungal infection (typically Aspergillus spp.).

Question 5

What are the risk factors for otitis externa?

Answer 5

The main risk factors for otitis externa are those that interfere with the normal protective mechanisms of the external auditory canal:

• Frequent water contact (e.g. swimmers and frequent hair washers)
• Humid environments
• Presence of ear polyps or foreign bodies
• Narrow ear canals
• Ear eczema or psoriasis
• Local trauma (e.g. hearing aids or excessive use of cotton buds)
• Immunocompromised patients
• Diabetics

Question 6

Which groups of patients are at greater risk of developing malignant otitis externa or complications?

Answer 6

Diabetic patients

Immunocompromised patients

Question 7

What are the symptoms of otitis externa?

Answer 7

• Progressive ear pain with a purulent discharge
• Itchiness
• Ear fullness
• Less common symptoms include:
  
  • Hearing loss
  • Tinnitus
  • Swollen ear

Question 8

What are the signs of otitits externa?

Answer 8

• On examination, the external ear canal will appear swollen and erythematous.
• The pinna may be swollen and the tragus may be tender on palpation.
• Any discharge is usually purulent; the colour of which may indicate the underlying cause:
  
  • White-yellow – related to bacterial infection
  • Thick white grey with visible hyphae or spores – fungal infection
  • Clear grey – otitis media

Question 9

How is otitis externa investigated?

Answer 9

• Clinical diagnosis, based on a thorough history and examination of the ear using an otoscope.
• If otitis externa is not resolving with antibiotics or there are signs of fungal disease on otoscopy, swabs of the discharge can be sent for culture.
• In recurrent disease, it may be useful to check glucose levels for diabetes mellitus.
• Any complicated cases of otitis externa may warrant a High Resolution CT (HRCT) scan to investigate the extent of the disease.

Question 10

Which grading scheme is used to quantify the severity of otitis externa?

Answer 10

The Brighton Grading Scheme

Question 11

How is otitis externa managed?

Answer 11

• prevention
• aural toileting
• topical antibiotics
• simple analgesia
• Steroid drops have been shown to be beneficial when there is evidence of canal inflammation. It acts to decrease the swelling (allowing the antibiotic to perforate) and reduce pain.

Question 12

When are oral antibiotics useful for otitis externa?

Answer 12

• Oral antibiotics have not been shown to offer any benefit in uncomplicated otitis externa and are usually avoided (unless evidence of cellulitis or pinna involvement)

Question 13

How should otitis externa be prevented?

Answer 13

• Any debris present should be removed by microsuction.
• Avoid exacerbating factors, such as swimming.
• If using a standard hearing aid, they should consider a bone-anchored hearing aid (BAHA) instead.
• Any underlying eczema or polyps should be managed appropriately.

Question 14

What are the complications of otitis externa?

Answer 14

• Malignant otitis externa
• Mastoiditis
• Osteomyelitis
• Intracranial spread

Question 15

What can cause complications in otitis externa?

Answer 15

• Delayed presentation
• Resistant organism
• Immunocompromised patient,

Question 16

What is malignant otitis externa?

Answer 16

• Malignant otitis externa is an extension of OE into the mastoid and temporal bones.
• It typically occurs in the elderly diabetics (or immunocompromised)
• It presents with severe pain and headaches, requiring an urgent CT scan. It can cause CN VII involvement and requires urgent debridement with IV antibiotics.

Question 17

What is acute otitis media?

Answer 17

• Infection of the middle ear

Question 18

What is the pathophysiology of acute otitis media?

Answer 18

• Bacterial infection of the middle ear results from nasopharyngeal organisms migrating via the Eustachian tube.
• The eustachian tube is more horizontal and shorter in children so they are more prone to getting middle ear infections from the eustachian tube as it is less prone to close during periods of high pressure such as coughing and sneezing so bacteria are more likely to be forced into the middle ear during a concurrent upper respiratory tract infection

Question 19

What are the causative organisms of acute otitis media?

Answer 19

• Haemophilus influenzae
• Streptococcus pneumoniae
• Moraxella catarrhalis
• Streptococcus pyogenes
• Respiratory syncytial virus (RSV) and rhinovirus.

Question 20

WHat are the risk factor of acute otitis media?

Answer 20

• Age (peak age 6-24 months)
• Parenteral / passive smoking
• Previous URTI
• Presence of enlarged adenoids
• Bottle feeding or dummy use (breast feeding is protective)
• GORD and ­BMI (in adults)

Question 21

What are the symptoms of acute otitis media?

Answer 21

• Pain
  
  • Pain can be difficult to interpret in young children, but they may tug at or cradle the ear that hurts, appear irritable, disinterested in food or have vomiting.
• Malaise
• Fever
• Coryzal symptoms, lasting for a few days

Question 22

What are the signs of acute otitis media?

Answer 22

• Tympanic membrane (TM) will look erythematous and may be bulging.
• TM could be perforated and so there may be discharge - yellow or purulent
  
  • The perforation will present with extreme pain and then sudden relief and ear discharge
• Conductive hearing loss
• Cervical lymphadenopathy
• Facial nerve function
• Signs of infection in the throat or orl cavity

Question 23

Why should the facial nerve be examined

Answer 23

Due to its anatomical course through the middle ear it is vulnerable.

Question 24

How should acute otitis media be investigated?

Answer 24

• Clinical diagnosis
• Bloods (FBC, CRP) will help confirm the inflammatory picture and are useful to gauge response to treatment.
• Any discharge should be sent for culture
• Blood cultures should be considered if pyrexial.

Question 25

How is acute otitis media managed?

Answer 25

• Mostly resolve spontaneously within 24 hours
• Analgesics
• There is no need to treat with antibiotics in most cases and a ‘watch and wait’ approach can be taken provided there are no worrying features

Question 26

What is vertigo?

Answer 26

The hallucination of movement

Question 27

What are the central causes of vertigo?

Answer 27

• Multiple sclerosis
• Posterior stroke
• Migraine
• Intracranial space occupying lesion

Question 28

What are the otological causes of vertigo?

Answer 28

• Benign Positional Paroxysmal Vertigo
• Meniere’s Disease
• Labyrinthitis
• Vestibular Neuronitis