From the Guidelines
Malignant otitis externa requires immediate aggressive therapy with intravenous antipseudomonal antibiotics, such as ciprofloxacin or piperacillin-tazobactam, for 2-4 weeks, followed by oral antibiotics for an additional 4-6 weeks, along with surgical debridement and supportive measures like ear canal cleaning and pain management. This condition is a severe, potentially life-threatening infection of the external ear canal that spreads to adjacent tissues, including bone, and is usually caused by Pseudomonas aeruginosa 1. The infection can extend to the temporal bone, facial nerve, and even intracranially if not properly treated.
Key Considerations
- Malignant otitis externa most commonly affects elderly diabetic patients, and strict glucose control is crucial during treatment 1.
- Patients with immunocompromised states, such as those with HIV infection or malignancies receiving chemotherapy, are also at increased risk 1.
- Treatment success is indicated by resolution of pain, otorrhea, and normalization of inflammatory markers, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) 1.
- Regular follow-ups, including weekly monitoring of inflammatory markers, are essential to assess treatment response and adjust therapy as needed.
Diagnostic Approach
- A clinical diagnosis of necrotizing otitis externa can be confirmed with a raised ESR plus an abnormal computed tomography or magnetic resonance imaging scan 1.
- Other imaging modalities, such as gallium scan, indium-labeled leukocyte scan, technetium bone scan, and single-photon emission tomographs, may also be used to evaluate the extent of the infection 1.
- Biopsy may be necessary to detect neoplasia if the diagnosis of malignant otitis externa is uncertain or response to therapy is incomplete 1.
From the Research
Definition and Overview of Malignant Otitis Externa
- Malignant otitis externa (MOE) is a progressive infection of the external auditory canal (EAC) that can spread to the temporal bone and affect intracranial structures 2.
- It is a rare but severe infection with high morbidity and mortality, commonly caused by Pseudomonas aeruginosa, although other pathogens like methicillin-resistant Staphylococcus aureus and fungi can also be involved 2, 3.
Risk Factors and Clinical Manifestations
- Major risk factors for MOE include diabetes mellitus, immunosuppression, and advanced age 2, 4.
- Clinical manifestations include severe otalgia (pain out of proportion to exam), severe otorrhea, and neurologic deficits, especially facial nerve involvement 2, 4.
- Red flags for MOE include previously diagnosed otitis externa not responsive to therapy and patients with major risk factors for MOE 2.
Diagnosis and Treatment
- Diagnosis is aided by computed tomography (CT) with intravenous contrast, which may demonstrate bony destruction of the temporal bone or skull base, and culture of EAC drainage should be performed 2.
- Treatment involves systemic antipseudomonal antibiotics, with ciprofloxacin being an effective option due to its antipseudomonal activity and good tissue penetration 5, 6, 3.
- Management should be individualized and involves multidisciplinary cooperation among specialties, including strict control of diabetes and monitoring with radiologic techniques 4.
- Surgical management is recommended in cases of refractory malignant otitis externa and facial nerve involvement 4.