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Presentation on theme: "MALIGNANT OTITIS EXTERNA"— Presentation transcript:

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 classification
1 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



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