A patient with CSOM and cholesteatoma develops sudden complete sensorineural hearing loss on the same side. Which mechanism is most likely responsible?
- A Cholesteatoma invasion of the endolymphatic sac
- B Thrombosis of the labyrinthine artery secondary to perilabyrinthitis
- C Labyrinthine fistula from erosion of the lateral semicircular canal ✓
- D Ossicular chain discontinuity affecting cochlear fluid dynamics
Correct answer: C. Labyrinthine fistula from erosion of the lateral semicircular canal
Explanation
The most common labyrinthine complication of cholesteatoma is a labyrinthine (perilymph) fistula through erosion of the lateral (horizontal) semicircular canal, which is the most vulnerable because of its close proximity to the epitympanum. Direct invasion of the labyrinth by cholesteatoma causes sudden SNHL and vertigo. The lateral SCC is involved in over 90% of labyrinthine fistulas from cholesteatoma. Labyrinthine artery thrombosis is extremely rare in this context.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.