This document discusses necrotizing otitis externa (NOE), a dangerous infection of the outer ear canal that mainly affects older diabetics. NOE begins as a simple ear infection but becomes infected by Pseudomonas aeruginosa, causing bone destruction in the ear canal and potential spread to nearby areas. Symptoms include persistent ear pain and discharge. Diagnosis involves examination showing surrounding tissue infection and bone exposure in the ear canal. Treatment requires long-term high-dose antibiotics and possible surgery to remove infected bone if antibiotics fail. Prognosis depends on prompt treatment but can be poor if facial nerve palsy or venous sinus thrombosis develop.

1. Necrotizing
Otitis Externa

2. Contents
 Pathogenesis
 Symptoms
 Diagnosis
 Differential Diagnosis
 Treatment
 Prognosis

3. Pathogenesis
of Necrotizing Otitis Externa

4. Necrotizing otitis externa: Pathogenesis
 Also known as malignant otitis externa
 A dangerous necrotizing form of otitis externa
 Occurs almost exclusively in older patients with diabetes mellitus
 Most cases begin with simple otitis externa
 Then becomes infected with Pseudomonas aeruginosa
 leading to ulceration and osteitis on the floor of the ear canal.
 The bone infection may subsequently spread to the
 middle ear,
 skull base,
 retromandibular fossa, and
 parotid compartment.

5. Symptoms
of Necrotizing Otitis Externa

6. Necrotizing otitis externa: Symptoms
 Initial history → insidious persistent otitis externa (doesn’t heal)
 At first there is moderate pain
 Pain becomes severe as disease becomes chronic
 Malodorous aural discharge may be present (not always)

7. Diagnosis
of Necrotizing Otitis Externa

8. Necrotizing otitis externa: Diagnosis
 Inspection
 Reveals signs of infection in surrounding tissues
 Otoscopy
 Almost always shows an ulcer on the canal floor with exposed, brownish bone and a
fetid (foul-smelling) discharge
 Smear (with sensitivity testing)
 Pseudomonas aeruginosa
 Radionuclide bone scan, CT :
 These studies define the extent of the infection and bone destruction.
 Diabetes mellitus is almost always present. Other immune defects should be
excluded.

9. Differential
Diagnosis
of Necrotizing Otitis Externa

10. Necrotizing otitis externa: DDX
 Differentiantion is mainly required from
 simple otitis externa and
 cholesteatoma of external ear canal.
 A biopsy should be taken if a tumor is suspected.
 Complications of chronic otitis media can produce similar findings.

11. Complications
of Necrotizing Otitis Externa

12. Necrotizing otitis externa: Complications
 The infection can lead to
 Otitis media
 Mastoiditis
 Petrostitis
 Soft tissue abscess
 Cranial nerve defects VII VIII IX X and XI
 Sepsis
 Venous sinus thrombosis
 In the late stage meningitis can occur (life threatening)

13. Treatment
of Necrotizing Otitis Externa

14. Necrotizing otitis externa: Treatment
 The ear canal is locally debrided and cleaned at regular intervals.
 In cases with minimal bone involvement, high doses of an antibiotic is
effective against Pseudomonas aeruginosa can be administered for 6
wks.
 DM should be closely monitored and adequately controlled.
 If there’s poor response to conservative therapy, extensive involvement, or if
complications arise, the affected bone should be resected.
 The surgery may be minor or may consist of petrosectomy, depending on the
extent of disease.

15. Prognosis
of Necrotizing Otitis Externa

16. Necrotizing otitis externa: Prognosis
 The prognosis is guarded and
depends on prompt, appropriate
treatment.
 In the cases that develop facial
nerve palsy or venous sinus
thrombosis, the survival chance is
only 50%.

17. References
 Rudolf Probst, M.D, Gerhard Grevers, M. D, Heinrich Iro, M.D. (2006).
Basic Otorhinolaryngology . : Thieme.
 Handzel, O., & Halperin, D. (2003, July 15). Necrotizing (malignant) external
otitis. American Family Physician. Retrieved March 25, 2022, from
https://www.aafp.org/afp/2003/0715/p309.html
 Google Images https://images.google.com/?gws_rd=ssl

18. Thank you!