Describe tuberculous otitis media.

Nature and Presentation

• Tuberculous otitis media is chronic middle ear infection by mycobacterium tuberculosis.
• It is uncommon but genuinely important in India, because it is curable with drugs yet routinely misdiagnosed as ordinary chronic suppurative otitis media and treated for years with drops and repeated surgery.
• Routes of infection — haematogenous spread from a pulmonary or other focus, which is commonest; via the eustachian tube from infected sputum or milk; and rarely direct through a perforation or from the mastoid cortex
• Consider it particularly in a patient with known or suspected tuberculosis elsewhere, in the immunosuppressed and HIV-positive, in the malnourished, and in children
• The classical features are A set OF departures from ordinary CSOM, and IT IS the discrepancy that should prompt the diagnosis:

Diagnosis and Treatment

• The diagnosis IS made BY thinking OF IT, and is confirmed histologically or microbiologically:
• Biopsy of the granulation tissue is the key investigation, showing caseating granulomas with langhans giant cells and epithelioid cells
• Discharge and tissue for ZIEHL-neelsen staining for acid-fast bacilli.
• PCR and cartridge-based nucleic acid amplification (GeneXpert).
• Search for tuberculosis elsewhere — chest radiograph, sputum examination, ESR, tuberculin test and HIV testing, since the ear is rarely the only site
• CT of the temporal bone shows the extent of bone destruction and sequestration
• Treatment IS medical, and this IS the central point: standard antitubercular chemotherapy under the national programme — an intensive phase of isoniazid, rifampicin, pyrazinamide and ethambutol followed by a continuation phase, for a total of 6 to 9 months or longer depending on the regimen and response
• Most cases resolve on chemotherapy alone, and surgery is not the primary treatment
• Surgery is reserved for obtaining a biopsy; for removal of sequestra and irreversibly diseased tissue; for complications such as facial palsy, subperiosteal abscess or intracranial disease; and for later reconstruction of the drum and ossicles once the disease is fully treated
• Warn about the ototoxicity of the drugs themselves — streptomycin and other aminoglycosides are vestibulotoxic and cochleotoxic, and ethambutol causes optic neuropathy, so hearing and vision must be monitored during treatment
• Screen and treat contacts, and notify under the national programme
• The diagnosis is made by thinking of it, and it is missed because nobody sends the granulations for histology
• Painless watery odourless discharge is the departure from ordinary chronic disease that should raise suspicion