Refining necrotising otitis externa management: A follow-up study on a departmental algorithm and the role of nuclear medicine imaging

Objective

This study evaluates the effectiveness of a departmental diagnostic and treatment algorithm for necrotising otitis externa (NOE), with a particular focus on the role of nuclear medicine imaging in improving diagnostic accuracy and patient outcomes.

Methods

A retrospective cohort analysis was conducted on patients admitted with suspected NOE to a major UK general hospital over a two-year period. Clinical presentation, imaging modalities, and treatment outcomes were reviewed to assess the algorithm's impact, with a focus on the diagnostic yield of CT, Technetium scans, and MRI, as well as treatment success rates and recurrence.

Results

Among 33 patients (mean age: 77 years), 28 were diagnosed with necrotising otitis externa (NOE). Diabetes was present in 41 %, and Pseudomonas aeruginosa was identified in 70 % of cases.

CT confirmed NOE in 21 patients (64 %), including two with skull base erosion. Among 12 patients with negative CT findings, 9 underwent Technetium bone scintigraphy, with 5 (56 %) yielding positive results. Two patients underwent MRI, confirming NOE in one case. One patient was diagnosed clinically. Overall, 6 of 12 patients (50 %) with negative CT results were ultimately diagnosed with NOE following further imaging.

All 28 diagnosed patients received prolonged intravenous or oral antibiotic therapy based on microbiological sensitivity. Of these, 24 had follow-up (mean: 5.6 weeks), with clinical resolution observed in 20 patients (83 %). Additional imaging was performed in 13 cases, including MRI (n = 4), CT (n = 5), Gallium scan (n = 1), PET-CT (n = 1), and combined CT/MRI (n = 2), primarily for persistent symptoms. Four patients were diagnosed with alternative conditions, including canal cholesteatoma and squamous cell carcinoma.

Overall, the cure rate within the cohort was 83 %, with no NOE recurrences or NOE-related mortality recorded during the follow-up period.

Conclusion

This study validates the efficacy of the department's updated NOE diagnostic and treatment algorithm, reinforcing the utility of technetium bone scans in cases where CT results are inconclusive. Findings highlight the importance of combining advanced imaging with clinical assessment for optimal NOE management, ensuring high-resolution rates and preventing unnecessary interventions.