Otitis Externa Definition

Otitis externa is an infection of the ear affecting different parts of the ear such as the skin, perichondrium or cartilage; otitis externa may affect a combination of these layers. It is called Otitis Externa because the external parts of the ears are affected and not the middle parts as in Otitis Media. The parts of the external ear include the Pinna, the External auditory meatus and the Tympanic Membrane. Hence Otitis Externa may affect the skin of the pinna or the cartilage of the pinna; it may affect the skin of the external auditory meatus or the bone of the canal and it can as well affect the Tympanic membrane.

What is Otitis Externa?

Otitis Externa is also known as Mediterranean ear or Swimmers ear because it can occur as a result of water in the external auditory canal. This disease has gradual onset and mostly unilateral (one ear is affected though both may be affected). This infection is mostly caused by Pseudomonas aeruginosa and Staphylococcus aureus but occurs less commonly by Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, Streptococci and Staphylococcus epidermidis.

Otitis Externa Epidemiology

Otitis Externa occurs worldwide with no gender bias and age predilection with Furunculosis being fairly common while keratosis obturans and invasive otitis externa(malignant otitis externa) are infrequent.

Otitis Externa Symptoms and Signs

Symptoms and Signs of Otitis Externa depend on the etiology.

1. Pain in the ear (Otalgia) Tragus pain is typical of Otitis Externa and it is often felt deep in the ear or behind the ear which is worsened with touching or movement of the ear and during chewing
2. Yellowish or green Ear discharge that is foul smelling from the external auditory canal
3. Pruritus (Itching of the ear)
4. Otoscopic examination reveals erythematous and edematous ear canal.
5. In fungal infections, hairlike black spores may even be visible
6. Furunculosis symptoms and signs include otalgia, trismus,hearing impairment due to canal narrowing, redness, fever and lymphadenitis

 

Classification of Otitis Externa

1. Acute Otitis Externa
2. Chronic Otitis Externa
3. Local Otitis Externa
4. Diffuse Otitis Externa
5. Unilateral Otitis Externa
6. Bilateral Otitis Externa

Otitis Externa Causes

1. Trauma such as ear piercing, boxing, ear syringing, and self-inflicted trauma through ear cleaning
2. Infective causes through bacteria, viruses, fungi, leprosy or syphilis
3. Inflammatory cause through chemical agents or burns
4. Idiopathic cause such as Psoriasis, Seborrhoeic dermatitis, Polychondritis and Keratosis obturans
5. Immune mediated causes such as Atopy and Allergy

Otitis Externa Infectious Causes

1. Pseudomonas aeruginosa
2. Staphylococcus aureus
3. Streptococcus pyogenes
4. Aspergillus spp.
5. Candida spp.
6. Enterobacter aerogenes
7. Proteus mirabilis
8. Klebsiella pneumoniae
9. Streptococci spp
10. Staphylococcus epidermidis

Examples of Local Otitis externa

1. Furunculosis
2. Cellulitis
3. Perichondritis

Examples of Diffuse Otitis externa based on Etiology

1. Idiopathic Otitis Externa
2. Traumatic Otitis Externa
3. Chemical Otitis Externa
4. Bacterial Otitis Externa
5. Fungal Otitis Externa
6. Climatic Otitis Externa

Other Examples of Otitis externa that occur as part of generalized skin infections

1. Allergic Otitis externa
2. Atopic Otitis externa
3. Psoriatic Otitis externa
4. Seborrhoeic Otitis externa

Types of Otitis Externa infections

1. Furunculosis
2. Keratosis obturans
3. Herpes Zoster Oticus
4. Malignant Otitis Externa (Invasive otitis Externa)
5. Otomycosis

Furunculosis

Furunculosis is an infection of the root of follicle and sebaceous glands that mostly affects the cartilaginous External auditory canal and the common agent implicated is staph aureus. Recurrence of Furunculosis is common and diabetes mellitus is a risk factor and can also lead to Malignant Otitis Externa. Some common symptoms of Furunculosis include pain in the affected ear, hearing impairment due to narrowing of the canal and lymphadenitis.

Furunculosis may spread backwards to affect the mastoid leading to the obliteration of the sulcus, or may spread forward into the parotid region or inwards through the notch of Rivinus to affect the eardrum (Tympanic Membrane)

Treatment of Furunculosis include use of Antibiotics, wick dressing and suction discharge(ear toileting)

Preauricular Sinuses Infection

Preauricular pits or sinuses may become infected forming abscess. Recurrence is common and treatment involves surgical excision after treatment with antibiotics as well as drainage of pus.

Herpes Zoster Oticus

Herpes Zoster Oticus affects the geniculate ganglion and causes hearing loss, vertigo, bullous eruptions and other lower cranial nerve palsies.

Seborrhoeic Dermatitis (Psoriatic dermatitis)

Seborrhoeic Dermatitis or Psoriatic dermatitis is mostly caused by Staphylococcus albus, Proteus spp, or Pseudomonas aeruginosa. Symptoms include itching, ear pains, Ear discharge, desquamation and impaired hearing. The External Auditory Canal (EAC) on examination appears is red, narrow, tender and swollen. Treatment of Seborrhoeic Dermatitis include wick dressing with steroid-antibiotic combination.

Eczematous Otitis Externa

Eczematous otitis externa or Allergic dermatitis can arise from EAC and can spread to affect the entire pinna and even the face; it is caused by contact dermatitis, food or chemical agents as a result of reaction to the presence of bacteria or fungi. Symptoms include scalling, fissuring and stenosis.

Otomycosis

Otomycosis is a type of otitis externa caused by fungi such as Aspergilus niger, Aspergilus flavus, Aspergilus fumigatus and Candida spp. Symptoms of otomycosis include pains in the ear, greyish-white and dark ear discharge, itching and hearing loss. Otomycocis usually occurs as a mixed infection with Pseudomonas species.

Diagnosis of Otomycosis is by isolation of typical conidiophores. Treatment includes syringing, use of drugs on wick dressing such as with Candibiotics, Mercurochrome, Locarcorten vioform, and Clotrimazole.

Keratosis obturans (Canal wall cholesteatoma)

Keratosis obturans( also known as Canal wall cholesteatoma) is an abnormal desquamation in the External auditory canal that occurs as a result of bony erosion and destruction of canal wall that is associated with chronic bronchitis and bronchiectasis. Treatment involves periodical removal of desquamation under general anesthesia.

Diffused infective Otitis Externa

Diffused infective Otitis externa is classified into 2 types: Infiltrative type and Desquamative type. Infiltrative infective otitis externa usually occur due to dirty finger nails or due to injuries from objects resulting in scanty ear discharge. The infection may spread to the auricle causing thickening. Desquamative infective otitis media occurs in hot humid climates and is mostly caused by organisms such as Bacteroides fragilis and Pseudomonas aeruginosa.

Malignant Otitis Externa (Invasive otitis externa)

Invasive otitis externa is also named as Malignant Otitis Externa or Necrotizing Otitis Externa; it is an infection of the external ear that originates in the meatus that rapidly progresses and spreads to the skull base. Malignant otitis externa often affects several cranial nerves such as cranial nerves V, VI, VII, IX, X, XI and XII; this infection has a high mortality rate as it can spread to the petrous apex and enter the cranial cavity through cranial fissures and causing vascular thrombophlebitis with complications such as Meningitis, Cavernous sinus thrombosis, skull base Osteitis and Osteomyelitis.

Malignant Otitis Externa is mostly seen in elderly patients with diabetes mellitus, in immunocompromised individuals and people who are severely malnourished.

Benecke staging of Malignant Otitis Externa

1. Stage 1: this is limited to the soft tissue and cartilage
2. Stage 2: occurs when there is involvement of the soft tissues and cartilage in addition to bony involvement
3. Stage 3: this occurs when there are stages 1 and 2 with intracranial involvement

The organisms responsible in most cases are Pseudomonas aeruginosa, Staphylococcus aureus and sometimes Aspergillus spp and Proteus spp in rare cases.

Diagnosis of Malignant Otitis Externa is by use of Technetium 99 scan or Gallium 67 scan.

Malignant Otitis Externa treatment can be surgical or medical (by use of antibiotics for 2 to 4 months).

Other Infections affecting the external ear

1. Leprosy
2. Syphilis
3. Cutaneous Leishmaniasis
4. Bullous myringitis (Otitis externa hemorrhagica) this is caused by Herpes simplex virus
5. Granular Myringitis this occurs as granulations that are seen superficially on the Tympanic membrane. It is a localized form of otitis externa that could result from chronic irritation on contact with wax, ear plug, grommet or foreign bodies. Treatment involves cauterization with silver nitrate.

Otitis Externa Diagnosis

1. Microscopy and culture for bacteria using swab material
2. Microscopy and culture for fungi of swab material
3. Gallium scan
4. Technetium 99 scan

Otitis Externa Complications

1. Septicemia
2. Formation of Cauliflower ear
3. Stenosis of the external auditory canal

Otitis Externa Prevention

1. Patients should avoid getting the canal wet when swimming or shampooing the hair
2. A cotton ball can be covered in a water-insoluble gel such as petroleum jelly and placed in the ear as a barrier to water contamination during swimming
3. Infection can also be prevented by using antiseptic otic preparations after swimming unless there is a history of tympanic membrane perforation or a current ear infection