Diagnosing necrotizing external otitis on CT and MRI: assessment of pattern of extension

W.L. van der Meer*, J.J. Waterval, H.P.M. Kunst, C. Mitea, S.A.H. Pegge, A.A. Postma

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Background and purpose Necrotizing external otitis (NEO) is a serious complication of external otitis. NEO can be classified according to-anterior, medial, posterior, intracranial, and contralateral-extension patterns. Currently there is no consensus on the optimal imaging modality for the identification of disease extension. This study compares NEO extension patterns on MR and CT to evaluate diagnostic comparability. Methods Patients who received a CT and MR within a 3-month interval were retrospectively examined. Involvement of subsites and subsequent spreading patterns were assessed on both modalities by a radiologist in training and by a senior head and neck radiologist. The prevalence of extension patterns on CT and MR were calculated and compared. Results All 21 included NEO cases showed an anterior extension pattern on CT and MR. Contrary to MR, medial extension was not recognized on CT in two out of six patients, and intracranial extension in five out of eight patients. The posterior extension pattern was not recognized on MR. Overall, single anterior extension pattern (62%) is more prevalent than multiple extension patterns (38%). Conclusion All anterior NEO extension pattern were identified on CT as well as MR. However, the medial and intracranial spreading patterns as seen on MR could only be identified on CT in a small number of patients. The posterior spreading pattern can be overlooked on MR. Thus, CT and MR are complimentary for the initial diagnosis and work-up of NEO as to correctly delineate disease extent through the skull base.
Original languageEnglish
Pages (from-to)1323-1328
Number of pages6
JournalEuropean Archives of Oto-Rhino-Laryngology
Issue number3
Early online date25 Apr 2021
Publication statusPublished - Mar 2022


  • Necrotizing external otitis
  • Skull base osteomyelitis
  • Malignant external otitis
  • Spreading patterns
  • CT
  • MR


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