From the Guidelines
Necrotizing otitis externa is the form of external otitis in which a bacterial infection extends from the auditory canal into the skull. This severe condition typically affects elderly diabetic patients or those who are immunocompromised, as noted in the clinical practice guideline on acute otitis externa 1. The most common causative organism is Pseudomonas aeruginosa.
Key Characteristics and Treatment
- Treatment requires aggressive management with intravenous antipseudomonal antibiotics such as ciprofloxacin (400mg IV twice daily) or ceftazidime (2g IV three times daily) for 4-6 weeks, followed by oral antibiotics for several additional weeks.
- Surgical debridement may be necessary in some cases.
- Patients typically present with severe ear pain, purulent discharge, and granulation tissue in the ear canal.
- The infection can spread to adjacent structures including the temporal bone, facial nerve, and even the brain, potentially causing cranial nerve palsies, meningitis, or brain abscesses.
- Early diagnosis through clinical examination, laboratory tests, and imaging studies (CT or MRI) is crucial for preventing these life-threatening complications, as emphasized in the guideline 1.
- Blood glucose control is essential in diabetic patients to improve treatment outcomes. It's also important to consider the patient's immune status, as immunocompromised conditions can increase the risk of necrotizing otitis externa, and special care should be taken when using irrigation in these patients 1.
From the Research
Forms of External Otitis
- Necrotizing otitis is a form of external otitis in which a bacterial infection extends from the auditory canal into the skull 2, 3, 4, 5.
- This condition is also known as malignant external otitis and is a relatively rare complication of external otitis 2.
- It occurs primarily in immunocompromised persons, especially older persons with diabetes mellitus, and is often initiated by self-inflicted or iatrogenic trauma to the external auditory canal 2.
Key Characteristics
- The most frequent pathogen is Pseudomonas aeruginosa 2, 3, 5.
- Patients with necrotizing external otitis complain of severe otalgia that worsens at night, and otorrhea 2, 3.
- Clinical findings include granulation tissue in the external auditory canal, especially at the bone-cartilage junction 2, 3.
- Facial and other cranial nerve palsies indicate a poor prognosis; intracranial complications are the most frequent cause of death 2.
Diagnosis and Treatment
- Diagnosis requires culture of ear secretions and pathologic examination of granulation tissue from the infection site 2.
- Imaging studies may include computed tomographic scanning, technetium Tc 99m medronate bone scanning, and gallium citrate Ga 67 scintigraphy 2.
- Treatment includes correction of immunosuppression (when possible), local treatment of the auditory canal, long-term systemic antibiotic therapy and, in selected patients, surgery 2, 3, 6.
Answer to the Question
The correct answer is: a. Necrotizing otitis