A patient with a large cholesteatoma eroding the lateral semicircular canal has a completely negative fistula test despite definite bony dehiscence confirmed on CT. The most likely explanation is:
- A Compensation by the contralateral labyrinth
- B Fistula sealed by cholesteatoma matrix
- C Dead labyrinth with no functioning vestibular end organ ✓
- D Fistula communicating with the cochlear aqueduct
Correct answer: C. Dead labyrinth with no functioning vestibular end organ
Explanation
The fistula test relies on a functioning vestibular labyrinth to generate nystagmus when pressure changes are transmitted through the dehiscent bone. If the labyrinth is dead, as occurs with long-standing extensive cholesteatoma destroying the inner ear, no response is elicited and the test is falsely negative even though a fistula exists. Sealing by matrix does not abolish the response in a live labyrinth, and contralateral compensation does not suppress the induced nystagmus during testing.
Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.