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.
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
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 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
17. Clinical and microscopic differences 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:
• Increased uptake during infection
• Monitoring and duration of antimicrobial
therapy
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
27. • Monotherapy with Ceftazidime
• Tobramycin can be used with minimal toxicity if peak
level doses are closely monitored
• Implantable gentamicin
• HBOT
28. Surgery:
• Debridement of nonviable sequestra of bone,
necrosed and Granulation tissues
• Wide resection:
Bony skull base
Stylomastoid foramen
Jugular bulb
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.
Eac-2.4cm, carti-8mm and bony-1.6mm. Fissures of santorini
Mortality in Malign otit ext-50%
Term coined by Chandeler in 1968
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
Fissures of santorini,
Complications in children include necrosis of TM, stenosis of the EAC, auricular deformity, and sensorineural and conductive hearing loss
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
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
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.
CT scan showing the soft tissue obliterating left external auditory canal left mastoid, infra-temporal fossa, skull base and involving the left TMJ
(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
SPECT-CT images provide greater definition of the pathological uptake in the right mastoid and petrous bone with no extension beyond the midline.
Duration of treatment: 06wks or as indicated by the results of radiologic studies and clinical response.
Gentamicin incorporated polymethyl-methacrylate beads were implanted, following surgical debridement, removed after 2 mths.
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
e.g. temporalis muscle flap
or microvascular free tissue transfer
