Malignant otitis Externa

1. Malignant Otitis Externa
Dr Anantha Chaitanya J
Intern
BGS GIMS
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2. Overview
1. Definition.
2. Nomenclature.
3. Clinico-Pathological Staging.
4. Pathogenesis.
5. Clinical Features.
6. Diagnosis.
7. Management.
8. Summary
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3. Definition
Malignant otitis externa is an aggressive and
potentially life-threatening infection of the
soft tissues of the external ear and
surrounding structures, quickly spreading to
involve the periosteum and bone of the skull
base.
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4. Nomenclature
 The nomenclature of this condition is confusing as the terms ‘skull base
osteomyelitis and ‘necrotizing external otitis are often interposed.
 It has been suggested that necrotizing external otitis should be used for
aggressive soft tissue infection in the absence of bony involvement and
that skull base osteomyelitis be used for the condition once bone infection
is confirmed.
 Malignant otitis externa is a misnomer as it is not a neoplastic process but
the term is unlikely to die and is still used regularly by clinicians.
 To aid clarification, Malignant otitis externa will be used as the term for
skull base osteomyelitis and necrotizing external otitis through this
section.
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5. Clinico-Pathological Staging5

6. Pathogenesis
 Aetiology:
1. Pseudomonas aeruginosa (95%).
2. Fungus (A. Fumigatus, A. Flavus, A. Niger).
 Predisposing Factors:
1. Diabetes Mellitus.
2. Immunocompromised state.
 Mechanism:
Cellulitis-> Chondritis-> Periostitis-> Osteitis ->Osteomyelitis.
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7. Pathogenesis
 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/
 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
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8. Clinical Features
 Long-standing otalgia (worst at night).
 Otorrhea.
 Cranial nerve palsy.
 Headaches.
 Fever.
 Neck stiffness.
 Altered levels of consciousness.
 Hallmark finding: Granulation tissue on floor of the ear canal
at the bony-cartilaginous junction.
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9. Clinical Features9

10. Clinical Features10

11. Diagnosis
Clinical.
ESR, CRP.
Biopsy.
Presence of microabscesses at surgery.
Pseudomonas aeruginosa on culture.
Positive bone scan.
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12. Diagnosis12

13. Diagnosis
 CT scan.
 MRI.
 Technetium-99m bone scan:
Osteoblastic activity Highly sensitive for bony infection.
 SPECT:
Good anatomic localization.
 Gallium scan:
Increased uptake during infection.
Monitoring and duration of antimicrobial therapy.
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14. Diagnosis14

15. Diagnosis15

16. Diagnosis
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17. Diagnosis17

18. Management: Aural toilet
 Local toilet to the external auditory canal is essential to
control the granulations and improve local pain control.
 The use of topical antibiotics is controversial. They are likely
to alter the microbiological flora of the external auditory canal
and prevent adequate culture and sensitivities at a future
date.
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19. Management: Systemic Antibiotics
 The treatment of choice for the management of malignant otitis externa is systemic
anti-Pseudomonas antibiotics.
 The drug often needs to be given for at least six weeks and in advanced cases, several
months.
 Parenteral Ciprofloxacin with or without an aminoglycoside and/or ceftazidime.
 Transition to oral antibiotics once the CRP and ESR start to fall.
 Use of oral ciprofloxacin alone.
 Resistance to fluoroquinolones appears to be increasing from 10 percent in the early
1990s to 56 percent (five of nine) more recently.
 Monotherapy with ceftazidime may be effective and tobramycin can be used with
minimal toxicity if peak level doses are closely monitored.
 Implantable gentamicin beads have been used with some success where oral therapy is
contra indicated but sensorineural hearing loss was a documented side effect.
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20. Management: Hyperbaric Oxygen
 Hyperbaric oxygen treatment is often used in centres easy
access to hyperbaric chambers.
 Several authors claim beneficial effects but a satisfactory
prospective study has yet to be reported.
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21. Management: Surgery
 There is now widespread agreement that surgical intervention
for malignant otitis externa should be reserved for a few
selected cases and no longer has the goal of removing all the
infected tissue.
 Surgery for the removal of sequestra, collections of pus and
debridement of necotized and granulating tissues can be
beneficial, but should only be used if the patient is
deteriorating clinically and if definable surgical goals can be
easily achieved.
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22. Summary
 Pseudomonas aeruginosa is responsible in over 95 percent of cases.
 Diabetes Mellitus and Immunocompromised states.
 Periostitis is the reason the disease spreads so quickly across the skull
base.
 Perform a Te-99 and magnetic resonance scan to assess the extent of the
condition
 Treat it early, aggressively and for an extended period.
 Use a Ga-67 scan to ascertain the end of residual infection.
 Consider Pseudomonas resistance.
 Consider hyperbaric oxygen if available.
 In children and non-diabeties biopsy the granulations to exclude other
conditions.
 Perform local toilet for symptom control.
 Reserve surgery for selected case.
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23. Bibliography
Scott Brown 7th edition.
Ballinger 16th edition.
Cummings 5th edition.
OCNA 2012.
Indian journal of nuclear medicine.
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24. Thank You
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