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Malignant otitis externa
- 1. MALIGNANT OTITIS EXTERNA DrManohar Suryawanshi ENT Resident, INHS Asvini
- 2. • Anatomy • Introduction •Microbiology • Pathogenesis • Diagnosis • Investigations • Treatment
- 6.
- 7. Definition • Aggressive andpotentially 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.
- 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 • Diabetesmellitus • Immuno-compromised status
- 11. Pathophysiology: • Cellulitis-> Chondritis->Periostitis-> Osteitis ->Osteomyelitis
- 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. • Thrombosis ofsigmoid sinus, IJV -> meningitis -> cerebral abscess • Haversian system of compact bone • Pneumatoized portion of the temporal bone involved late • Otic capsule is usually spared
- 14. Clinical features: • Long-standingotalgia (worst at night) and otorrhea
- 15. • Cranial nervepalsy • Headaches, fever • Neck stiffness • Altered levels of consciousness
- 16. Hallmark finding: granulationtissue on floor of the ear canal at the bony-cartilaginous junction
- 17. Clinical and microscopicdifferences between bacterial and fungal malignant otitis externa Pathogen Age Diabetes Immunosuppres sion Granulation tissue Middle ear/mastoid involvement Histology Bacterial Older Common 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
- 19. Investigations: • CT scan •MRI • Technetium-99m bone scan: Osteoblastic activity Highly sensitive for bony infection • SPECT: Good anatomic localization
- 20. Gallium scan: • Increaseduptake during infection • Monitoring and duration of antimicrobial therapy
- 24. technetium Tc 99mMDP bone scan
- 25. Clinicopathological classification 1 Clinicalevidence 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
- 27. • Monotherapy withCeftazidime • Tobramycin can be used with minimal toxicity if peak level doses are closely monitored • Implantable gentamicin • HBOT
- 28. Surgery: • Debridement ofnonviable sequestra of bone, necrosed and Granulation tissues • Wide resection: Bony skull base Stylomastoid foramen Jugular bulb
- 29. • Introduction ofviable, vascularized tissue into the bed
- 30. References • Scott brown7th edition • Ballinger 16th edition • Cummings 5th edition • OCNA 2012 • Indian journal of nuclear medicine
- 31.
Editor's Notes
- #4 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.
- #5 Eac-2.4cm, carti-8mm and bony-1.6mm. Fissures of santorini
- #7 Mortality in Malign otit ext-50%
- #8 Term coined by Chandeler in 1968
- #11 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
- #12 Fissures of santorini,
- #14 Complications in children include necrosis of TM, stenosis of the EAC, auricular deformity, and sensorineural and conductive hearing loss
- #19 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
- #20 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
- #21 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.
- #22 CT scan showing the soft tissue obliterating left external auditory canal left mastoid, infra-temporal fossa, skull base and involving the left TMJ
- #23 (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
- #24 SPECT-CT images provide greater definition of the pathological uptake in the right mastoid and petrous bone with no extension beyond the midline.
- #27 Duration of treatment: 06wks or as indicated by the results of radiologic studies and clinical response.
- #28 Gentamicin incorporated polymethyl-methacrylate beads were implanted, following surgical debridement, removed after 2 mths.
- #29 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
- #30 e.g. temporalis muscle flap or microvascular free tissue transfer