Which of the following is the MOST common intracranial complication of CSOM with cholesteatoma, and what is the pathogenetic mechanism by which cholesteatoma erodes bone?

• A Brain abscess; fungal invasion directly destroys bone through mechanical pressure
• B Meningitis; bacteria from the ear canal invade through Eustachian tube to the meninges
• C Lateral sinus thrombophlebitis; cholesteatoma secretes fibrinolysins that dissolve sinus walls
• D Extradural (epidural) abscess; collagenase and osteoclast-activating cytokines (IL-1, TNF) secreted by cholesteatoma epithelium cause bone erosion ✓

Explanation

Extradural abscess is the most common intracranial complication of CSOM with cholesteatoma, followed by meningitis, then brain abscess. Cholesteatoma causes osteolysis via: (1) pressure necrosis from expanding keratinous mass, (2) enzymatic destruction — keratinases, collagenases, proteases, and (3) cytokine-mediated osteoclast activation (IL-1, IL-6, TNF-alpha). Bone erosion commonly involves the tegmen tympani, lateral semicircular canal, and facial canal, accounting for specific complications.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.