Otitis Externa - IV

• A destructive and potentially fatal form of otitis externa, which extends beyond the external auditory canal to the base of the skull.

• Incidence: Rare, most commonly in elderly uncontrolled diabetics.

• Causative Organisms: Pseudomonas aeruginosa.

• Pathogenesis: The organism produces enzymes, which cause necrotizing vasculitis ≫ necrosis. Diabetic micro-angiopathy of the blood vessels ≫ necrosis.

• Clinical picture:

1. Severe stabbing earache.

2. Granulation tissue in the floor of the external canal, at the junction of cartilaginous part with bony part.

3. Otorrhoea: scanty, sero-sanginous and purulent.

• Investigations:

1. CT scans of the temporal bone → skull base destruction.

2. Bone scans (Gallium and Technetium) to assess severity of bone destruction and prognosis.

3. Biopsy: to exclude malignancy.

4. Culture and sensitivity tests of the discharge.

• Complications:

1. Spread of infection ≫Osteomyelitis of the temporal bone and skull base.

2. Cranial nerves palsy:

• Facial nerve, at stylo-mastoid foramen.

• Glosso-pharyngeal, vagus and accessory nerves, at jugular foramen.
  

• Treatment:

1. Systemic treatment:

• Control of diabetes.

• Massive antibiotic therapy (Anti-pseudomonas) e.g. quinolones and aminoglycosides, continued until complete cure in at least 6 weeks.

2- Local treatment:

• Aural toilet i.e. repeated removal of the ear discharge by suction

• Antbiotic ear drops.

3- Surgical treatment:

• Removal of granulations and debridement of necrotic tissues.

Category: ENT Notes