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Malignant Otitis Externa
Malignant otitis externa is an aggressive infection of the external ear and skull base that commonly affects older diabetics. It is caused mainly by Pseudomonas aeruginosa bacteria invading the external ear canal and spreading through fissures in the bone. Symptoms include severe ear pain, discharge, and potentially cranial nerve palsies. Diagnosis involves culture, imaging like CT showing bone destruction, and ruling out other causes. Treatment requires long-term antibiotics like ciprofloxacin, tight blood sugar control, and sometimes hyperbaric oxygen or surgery. Prognosis has improved but mortality remains high if the infection spreads intracranially or causes multiple cranial neuropathies.
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Malignant Otitis Externa
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- 2. Malignant otitisexterna 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. DEFINITION
- 3. NOMENCLATURE Malignant otitisexterna is a misnomer as it is not a neoplastic process In 1968, Chandler described this otitis externa as malignant because he observed an aggressive clinical behavior, poor treatment outcome, and a high mortality rate for the patients affected by this disease. SYNONAMES : - Necrotizing otitis externa -Skull base osteomyelitis
- 4. Microbiology Bacterial - Pseudomonasaeruginosa (95%) - Staphylococcus aureus , S epidermidis . Fungal organism - Aspergillus fumigatus
- 5. Predisposing factors Oldage Diabetes mellitus Immuno-compromised status
- 7. Pathophysiology Infection from theEAC spreads Through the fissures of Santorini Infection spreads medially to the tympanomastoid suture, and along venous canals and fascial planes The compact bone of the skull base becomes replaced with granulation tissue, Bone destruction Progressive spread of infection to skull base foramina causes cranial neuropathies.
- 9. Clinical features Long-standingsevere otalgia (worst at night) aggravated by chewing Otorrhea Hearing loss
- 10. Clinical features purulentotorrhea with a swollen, tender external auditory canal Hallmark finding: granulation tissue on floor of the ear canal at the bony- cartilaginous junction
- 11. Clinical features Cranialnerve palsy Headache Neck stiffness Altered levels of consciousness
- 12. Differential diagnosis Carcinomaof the ear canal Granulomatous diseases Paget's disease Nasopharyngeal malignances Clival lesions Fibrous dysplasia
- 13. Diagnosis There isno single pathognomonic criterion that defines malignant otitis externa History :(Age ,diabetic ,may give history of trauma to ear by irrigation or cleaning ) Complete head and neck examination: (signs of otitis externa with or without cranial nerve palsy)
- 14. Diagnosis Investigations ESR ,CRPraised but not specific Ear swab culture/sensitivity ______ Pseudomonas Tissues biopsy __________ Rule out malignancy HbA1C _________ Diabetic control
- 15. Diagnosis Radiological investigations Ctscan : Defines the anatomical extent of the disease Remains the initial investigation of choice MRI scan Useful for assessing the initial severity of the disease Excellent at delineating the extent of soft tissue disease Intracranial complications
- 16. Diagnosis Radiological investigations Radioisotope scans TC 99 bone scan ------ Bone involvement Gallium 67 ------------- Monitoring Indium In 111-labeled leukocyte scans
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- 22. Staging and classification Stage 1Clinical 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
- 23. Management Successful managementof MOE frequently requires collaboration with an endocrinologist, neurologist, radiologist, and infectious disease specialist. Important principles of treatment include aggressive control of diabetes, reversal of acidosis, and improvement of immunocompetency where possible
- 24. Management Medical Management Meticulousglucose control Aural toilet systemic anti-Pseudomonas antibiotics (treatment of choice )
- 25. Management Medical Management Fluoroquinolonesare active against P. aeruginosa. For at least 6 to 8 weeks- oral and intravenous ciprofloxacin Ceftazidime provide an alternative to ciprofloxacin with or without Aminoglycoside Amphotericin B is the most commonly used antifungal agent for fungal
- 26. Management Hyperbaric Oxygen (HBO): HBO increases the partial pressure of oxygen, improving hypoxia and allowing greater oxidative killing of bacteria. Used only as an adjunct to antimicrobial therapy
- 27. Management Surgical: Removal ofsequestra, collections of pus & debridement of necrotized & granulations Facial nerve decompression is not indicated for patients with facial paralysis.
- 28. Prognosis Disease recurrence 9-27% Due to inadequate length of therapy and manifests as recurrent headache and otalgia Can recur as long as one year after treatment is completed
- 29. Prognosis Mortality Decreasedto 20% with the introduction of appropriate antibiotics, improved imaging modalities, and increased awareness of the disease Mortality remains high for patients with cranial neuropathies (other than VII), intracranial complications, or with irreversible systemic immunosuppression.
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Editor's Notes
- #5 The causative agent - Pseudomonas aeruginosa ( a gram-negative – aerobe) --------95% - Other, including Staphylococcus aureus , S epidermidis , Proteus mirabilis , Klebsiella,
- #6 The most common and important risk factor for MOE is long standing diabetes. • People with recurrent attacks of severe MOE should be screened for diabetes if they aren’t already aware of suffering from it. • Age especially elderly patients • Any condition causing immunosuppression
- #12 IN Advance disease
- #14 The diagnosis is generally made from a range of clinical, laboratory, and radiographical findings In this study, more than two-thirds of our patients with malignant external otitis had a history of ear irrigation (generally for the purpose of disimpacting cerumen)
- #16 These are important adjuncts for determining the presence of osteomyelitis, the extent of disease, and response to therapy.
- #17 Technitium -99 can detect early bone involvement But not used to assess the response to treatment as it is absorbed by osteoblast and osteoclast that continue remodeling even after infection is settled –remain positive for up to 9 month Gallium (Ga-67) is absorbed by leukocytes and is a more sensitive monitor of infection. The scan quickly returns to normal after the infection has resolved and as such, is a good measure to ascertain when to terminate treatment
- #18 CT scan showing the soft tissue obliterating left external auditory canal left mastoid, infra-temporal fossa, skull base and involving the left TMJ.
- #19 Axial CT scan of a 63-year-old patient who has diabetes and left malignant otitis externa showing bony erosion of the posterior external auditory canal and mastoid cortex
- #20 MRI of same patient: axial T1WI (A), post contrast (B) and fat saturated T2WI (C) demonstrates extensive inflammation and enhancement of the left EAC, periauricular region, masticator, parotid and parapharyngeal spaces. These areas are hyperintense on T2WI. Note mastoid airspace disease. This can be mistaken for an aggressive tumor.
- #22 Fig. 2. Anterior and posterior views of technetium Tc 99m MDP bone scan of patient from Fig. 1showing increased uptake in the left mastoid.
- #23 Staging depending on clinical and radiological features
- #25 Culture-directed therapy should always be the goal of treatment
- #26 Early infections may be treated solely with oral ciprofloxacin In more advanced stages, parenteral antibiotics may be indicated initially Ceftazidime –upto 2 g i/v tds
- #27 Hyperbaric oxygen therapy Used only as an adjunct to antimicrobial therapy; it should not be used alone. May be helpful for patients with complications, experiencing a poor response to therapy, or with recurrent cases