Necrotizing (Malignant) External Otitis
Malignant Otitis Externa (MOE) is a life threatening, progressive bacterial infection of the external auditory canal (EAC), mastoid and skull base. It most commonly occurs in elderly diabetics or in an otherwise immune compromised host. In nearly all cases Pseudomonas aerugenosia is the causative organism, difficult-to-treat bacteria.
There is inflammation and damage of the bones and cartilage at the base of the skull-Osteomylitis. The infection spreads from the floor of the ear canal to the nearby tissues and into the bones at the base of the skull. The infection and inflammation may damage or destroy the bones. The infection may spread more and affect the cranial nerves, brain, or other parts of the body.
Clinical findings include granulation tissue in the external auditory canal, especially at the bone-cartilage junction
Osteitis of the temporal and adjacent bones was initially described in 1959. Because of the high mortality rate (46 percent) in early series, this condition is often referred to as â€œmalignant otitis externa.â€ It is also called â€œnecrotizing external otitis,â€ a term that emphasizes the destructive nature of the infection. Osteitis of the base of the skull,â€ the most recent but less popular name for this condition.
â€¢ Drainage from the ear – yellow, yellow-green, foul smelling, and persistent.
â€¢ Ear pain- felt deep inside the ear and may get worse when moving head, more at night
â€¢ Hearing loss
â€¢ Signs of cellulites, cranial nerve palsy
Mandatory laboratory tests include an erythrocyte sedimentation rate (ESR); white and red blood cell counts, glucose and creatinine levels, and culture of ear secretions. The purpose of the culture is to look for bacteria or fungi, usually the bacteria Pseudomonas.
The ESR is typically elevated in necrotizing external otitis; therefore, it is a useful indicator of treatment response. Before topical or systemic antibiotic therapy is started, ear secretions should be cultured, because susceptibility patterns may change after the initiation of treatment (i.e., bacteria might become resistant to an antibiotic during treatment).
Pathologic examination of granulation tissue removed from the external auditory canal is essential to exclude malignant processes, which may present as nonresponding inflammatory disease.
Imaging to prove the extension of infection to bony structures is generally necessary to establish the diagnosis of necrotizing external otitis. Imaging modalities include computed tomographic (CT) scanning, technetium and gallium scintigraphy.
CT scanning is used to determine the location and extent of diseased tissue .The temporal bone is the first bone to be affected, with imminent involvement of the petrous apex and mastoid.
Treatment often lasts for several weeks to months, because it is difficult to treat the bacteria.
Strict control of diabetes mellitus is mandatory, although it can be difficult to achieve during the acute illness. Other immunosuppressive states and morbid conditions also must be aggressively managed.
Antibiotics that are effective against the microorganism are given for long periods of time. They may be given through an intravenously or by mouth.
Antibiotics that are effective against P. aeruginosa include aminoglycosides, penicillins (especially piperacillinâ€“tazobactam , ceftazidime , and imipenem
Treatment can be guided by monitoring ESR and Gallium scans.
Surgery has a definite but increasingly limited role in the treatment of osteitis of the base of the skull. Although bone sequestra and abscess are treated surgically, further extension of the operation may be counterproductive because it may expose healthy bone to the infection. This is done under GA.
Can be bad, if not treated aggressively. Malignant otitis externa may responds to long-term treatment, but it may return in the future. Facial and other cranial nerve palsies indicate a poor prognosis; intracranial complications are the most frequent cause of death
â€¢ Damage to the cranial nerves, skull, or brain
â€¢ Return of infection, even after treatment
â€¢ Spread of infection to the brain or other parts of the body