Cranial nerve involvement in malignant external otitis: implications for clinical outcome

Malignant external otitis is an uncommon, potentially lethal infection of the temporal bone primarily affecting elderly diabetic patients.

To determine whether cranial nerve involvement in malignant external otitis affects or predicts the clinical outcome in terms of morbidity and mortality.

Diagnosis of malignant external otitis was established in 23 patients (average age, 71 yr; range, 39-87) based on inclusion criteria of severe pain, otitis externa refractory to conventional treatments, diabetes mellitus, and Pseudomonas aeruginosa detection. Computed tomography confirmed temporal bone involvement extending outside the external auditory canal.

Retrospective analysis of hospital records.

Ten of 23 (43.5%) patients showed cranial nerve involvement. The following cranial nerves were affected: facial nerve (6/10), lower cranial nerves (combination of IX, X, XI, XII) (3/10), and extended nerve palsy (VI, VII, IX, X, XI) (1/10). Thirteen of 23 (56.5%) patients displayed no cranial nerve involvement. All patients were treated with long-term, high-dose antibiotic treatment dependent on the microbiological findings.

All patients with lower cranial nerve palsy recovered normal function; however, the facial nerve palsy was significantly less likely to improve by medical treatment. Cranial nerve involvement did not affect the patient survival rate under an optimized medical treatment in our series.