Electrocochleography (ECochG) is performed in a 30-year-old woman with episodic vertigo, fluctuating hearing loss and tinnitus. Which finding supports the diagnosis of Ménière disease?

• A Prolonged Wave V interpeak latency
• B Absent cochlear microphonic
• C Summating potential to action potential (SP/AP) ratio greater than 0.5 ✓
• D Elevated acoustic reflex threshold with reflex decay

Explanation

Endolymphatic hydrops distorts the basilar membrane, producing an enlarged negative summating potential relative to the action potential. An SP/AP ratio exceeding 0.5 (some texts use 0.4) is the classic electrocochleographic marker of Ménière disease. An absent cochlear microphonic would indicate gross cochlear or neural failure rather than hydrops, and prolonged Wave V latency points to a retrocochlear lesion, eliminating both distractors.

Reference: Cummings Otolaryngology: Head and Neck Surgery, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.