A patient presents with episodic vertigo lasting 20–30 minutes, ipsilateral ear fullness, and low-frequency SNHL fluctuating in severity. Pure-tone audiogram shows a rising configuration (better high-frequency hearing). The most specific electrophysiological test to confirm endolymphatic hydrops in this condition is:
- A Absence of acoustic reflexes on ipsilateral stimulation
- B Electrocochleography (ECoG) showing summating potential to action potential (SP/AP) ratio >0.35–0.45 ✓
- C Absent cVEMP with raised threshold on ipsilateral side
- D Canal paresis on caloric testing with directional preponderance contralaterally
Explanation
Meniere's disease (endolymphatic hydrops) is characterised by episodic vertigo, fluctuating low-frequency SNHL, tinnitus, and aural fullness. Electrocochleography (ECoG) measures the SP/AP ratio — endolymphatic hydrops enlarges the summating potential relative to the action potential. An SP/AP ratio >0.35–0.45 (varying by centre, commonly 0.4 as threshold) is the most specific ECoG finding supporting Meniere's. Caloric canal paresis is a non-specific finding of labyrinthine hypofunction; cVEMP changes are supportive but not pathognomonic; absent acoustic reflexes occur with middle ear or cochlear pathology generally.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.