1. MALIGNANT OTITIS EXTERNA
Dr Manohar Suryawanshi
ENT Resident, INHS Asvini

2. Anatomy
Introduction
Microbiology
Pathogenesis
Diagnosis
Investigations
Treatment

3. body of the auricle -elastic fibrocartilage and is a continuous plate except for anarrow gap between the tragus and the anterior crus of the helix-incisura terminalis. lateral surface of the auricle prominences and depressions. Curved rim of helix-Darwins tubercle-small prominence, Concha devided by descending limb of helix. Cymba conchae-suprameatal triangle. Below the crus of the helix -tragus, Opposite the tragus, at the inferior limit of the antihelix, is the antitragus.

4. Eac-2.4cm, carti-8mm and bony-1.6mm. Fissures of santorini

6. Introduction
Mortality in Malign otit ext-50%

7. Definition
Aggressive and potentially life-threatening infection of the soft tissues of the external ear and surrounding structures, quickly spreading to involve the periostium and bone of the skull base.
Term coined by Chandeler in 1968

8. Microbiology: Pseudomonas aeruginosa (95%)
Fungus (A. Fumigatus, A. Flavus, A. Niger)

9. Fungal MOE: HIV more commonly than in those who have diabetes
From middle ear or mastoid in contrast to pseudomonal
Pseudomonas infections CD4 levels < 100 cells/mm
AspergillusCD4 counts <50 cells/mm

10. Predisposing factors Diabetes mellitus Immuno-compromised status
endarteritis, small vessel obliteration,which, coupled with the ability of Pseudomonas to invade vessel walls
and cause a vasculitis with thrombosis and coagulation necrosis of surrounding tissue, underlies the pathophysiology of this disease Microangiopathy, impaired phagocytosis, Cerumen of high PH in DM

11. Pathophysiology: Cellulitis-> Chondritis-> Periostitis->
Osteitis ->Osteomyelitis
Fissures of santorini,

12. Facial nerve (stylomastoid foramen) 60%
IX, X and XI
V and VI (petrous apex)
Clivus and contralateral temporal bone can be involved
Infection can spread anteriorly into the sphenoid and to the carotid

13. Haversian system of compact bone
Thrombosis of sigmoid sinus, IJV -> meningitis -> cerebral abscess
Haversian system of compact bone
Pneumatoized portion of the temporal bone involved late
Otic capsule is usually spared
Complications in children include necrosis of TM, stenosis of the EAC, auricular deformity, and sensorineural and conductive hearing loss

14. Clinical features:
Long-standing otalgia (worst at night) and otorrhea

15. Cranial nerve palsy
Headaches, fever
Neck stiffness
Altered levels of consciousness

16. Hallmark finding: granulation tissue on floor of the ear canal at the bony-cartilaginous junction

17. Clinical and microscopic differences between bacterial and fungal malignant otitis externa
Pathogen
Age
Diabetes
Immunosuppression
Granulation
tissue
Middle ear/mastoid
involvement
Histology
Bacterial
Older
Common + -
Gram -ve rod
Fungal
Younger
Less
common
More common
Septate hyphae,
calcium oxalate crystals

18. Diagnosis: Clinical Biopsy Pseudomonas aeruginosa on culture
Supported by a positive bone scan and/or
the presence of microabscesses at surgery
ESR, CRP
combination of pain,granulations, otorrhea and resistance to local therapy for at least eight to ten days are highly sensitive for making a
diagnosis of malignant otitis externa. Diabetes or other immunocompromised state, Silver stain for fungal

19. Technetium-99m bone scan: Osteoblastic activity
Investigations:
CT scan
MRI
Technetium-99m bone scan:
Osteoblastic activity
Highly sensitive for bony infection
SPECT:
Good anatomic localization
1. CT scan shows even small cortical erosion of the tympanic bone and is a useful first-line test. Disadvantages of CT :under appreciation of the
soft tissue and intracranial extent of disease
2. Tc99 MDP detects as little as 10% demineralization
3. Involvement of the retrocondylar fat pad on MRI has been proposed as an early diagnostic

20. Gallium scan: Increased uptake during infection
Monitoring and duration of antimicrobial
therapy
1. Ga scan every 4wk, -ve when infection clears
2. Diagnostic accuracy (and expense) may be afforded by the simultaneous acquisition of a SPECT technetium-99m bone scan and indium-111–labeled leukocyte scan.

21. CT scan showing the soft tissue obliterating left external auditory canal left mastoid, infra-temporal fossa, skull base and involving the left TMJ

22. (a) increased signal beneath the skull base that reflects the inflammatory process (arrowed). (b) Indium-labelled white cell
scan of the same patient showing increased uptake in the temporal bone

23.  SPECT-CT images provide greater definition of the pathological uptake in the right mastoid and petrous bone with no extension beyond the midline.

24. technetium Tc 99m MDP bone scan

25. Clinicopathological classification1
Clinical evidence of malignant otitis externa with
infection of soft tissues beyond the external auditory
canal, but negative Tc-99 bone scan 2
Soft tissue infection beyond external auditory canal with
positive Tc-99 bone scan 3
As above, but with cranial nerve paralysis
3a- Single
3b -Multiple 4
Meningitis, empyema, sinus thrombosis or brain abscess

26. Treatment: Medical Early infections- oral fluoroquinolone
Advanced stages- parenteral antibiotics
may be indicated
Duration of treatment: 06wks or as indicated by the results of radiologic studies and clinical response.

27. Monotherapy with Ceftazidime
Tobramycin can be used with minimal toxicity if peak level doses are closely monitored
Implantable gentamicin
HBOT
Gentamicin incorporated polymethyl-methacrylate beads were implanted, following surgical debridement, removed after 2 mths.

28. Surgery:
Debridement of nonviable sequestra of bone, necrosed and Granulation tissues
Wide resection:
Bony skull base
Stylomastoid foramen
Jugular bulb
1.Surgical resection-resistant to therapy traditional mastoidectomy should theoretically not be effective in
débriding the infection. facial nerve is involved in the region of the stylomastoid foramen, facial nerve decompression

29. Introduction of viable, vascularized tissue into the bed
e.g. temporalis muscle flap
or microvascular free tissue transfer

30. References Scott brown 7th edition Ballinger 16th edition
Cummings 5th edition
OCNA 2012
Indian journal of nuclear medicine

31. THANK YOU