Malignant Otitis Externa

Skull base osteomylitis

1. Malignant Otitis Externa Dr. Mamoon Ameen

2. 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. DEFINITION

3. NOMENCLATURE Malignant otitis externa 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 - Pseudomonas aeruginosa (95%) - Staphylococcus aureus , S epidermidis . Fungal organism - Aspergillus fumigatus

5. Predisposing factors Old age Diabetes mellitus Immuno-compromised status

6. Pathophysiology Infection from the EAC 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.

7. Clinical features Long-standing severe otalgia (worst at night) aggravated by chewing Otorrhea Hearing loss

8. Clinical features purulent otorrhea with a swollen, tender external auditory canal Hallmark finding: granulation tissue on floor of the ear canal at the bony- cartilaginous junction

9. Clinical features Cranial nerve palsy Headache Neck stiffness Altered levels of consciousness

10. Differential diagnosis Carcinoma of the ear canal Granulomatous diseases Paget's disease Nasopharyngeal malignances Clival lesions Fibrous dysplasia

11. Diagnosis There is no 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)

12. Diagnosis Investigations ESR ,CRP raised but not specific Ear swab culture/sensitivity ______ Pseudomonas Tissues biopsy __________ Rule out malignancy HbA1C _________ Diabetic control

13. Diagnosis Radiological investigations Ct scan : 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

14. Diagnosis Radiological investigations Radioisotope scans TC 99 bone scan ------ Bone involvement Gallium 67 ------------- Monitoring Indium In 111-labeled leukocyte scans

15. CT

16. CT

17. MRI

18. Gallium scan

19. TC99

20. Staging and classification Stage 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

21. Management Successful management of 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

22. Management Medical Management Meticulous glucose control Aural toilet systemic anti-Pseudomonas antibiotics (treatment of choice )

23. Management Medical Management Fluoroquinolones are 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

24. 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

25. Management Surgical: Removal of sequestra , collections of pus & debridement of necrotized & granulations Facial nerve decompression is not indicated for patients with facial paralysis.

26. 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

27. Prognosis Mortality Decreased to 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.

28. Thank you