Malignant Otitis Externa Follow-up

Updated: Mar 19, 2018
  • Author: Brian Nussenbaum, MD, FACS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Follow-up

Prognosis

A study by Lee et al indicated that prognostic factors in malignant external otitis include the duration of diabetes mellitus, the C-reactive protein level and the erythrocyte sedimentation rate (inflammatory markers), the extent of the malignant external otitis as assessed through imaging studies, and cranial nerve involvement. [21]

In a retrospective study, Stevens et al stratified malignant external otitis into severe and nonsevere categories, with severe cases characterized by at least two of the following characteristics: cranial nerve VII palsy, a positive fungal culture, relapse, surgical treatment, and major radiographic findings. Compared with cases in the nonsevere category (16 patients), those classified as severe (12 patients) were associated with longer courses of antibiotics and with more admissions and relapses related to the condition. Moreover, cure was achieved in only four of the severe patients, compared with 14 of the nonsevere cases. [22]

A literature review by Mion et al indicated that in patients with fungal malignant external otitis, treatment tends to be effective in cases in which surgical debridement has not been employed, facial palsy is absent, the condition was caused by an Aspergillus species, and imaging findings at diagnosis and follow-up are absent. However, the investigators cautioned that surgical debridement may have been associated with less effective treatment because, possibly, it tended to be used in patients with more aggressive, advanced disease. [23]

Disease recurrence

Disease recurrence is reported in 9-27% of patients. It usually is related to inadequate length of therapy and manifests as recurrent headaches and otalgia, not as otorrhea. The ESR begins increasing again.

Malignant external otitis (MEO) can recur as long as one year after treatment is completed; thus, a patient should not be considered cured until that time.

Mortality

Chandler reported a mortality rate of 50% in the original series. The mortality rate has decreased to 20% with the introduction of appropriate antibiotics, improved imaging modalities, and increased awareness of the disease.

Most current studies report a mortality rate of less than 10%, but mortality remains high for patients with cranial neuropathies (other than VII), intracranial complications, or with irreversible systemic immunosuppression.

A retrospective clinical study investigated the prognostic value of serial temporal bone MRI follow-up patterns in patients with necrotizing otitis externa. The most common finding was retrocondylar fat infiltration, which was also the earliest change seen. The patients with combined extension patterns (50%) had significantly lower overall survival compared with the patients with limited extension patterns or single extension patterns, suggesting that combined extension patterns, versus single or limited extension patterns, may be a poor prognostic factor in patients with necrotizing otitis externa. [15]