Electrocochleography (ECoG) in Meniere's disease shows an elevated summating potential to action potential (SP/AP) ratio. What threshold ratio is considered abnormal?
- A >0.2
- B >0.3
- C >0.4 ✓
- D >0.5
Correct answer: C. >0.4
Explanation
In ECoG, the SP/AP ratio >0.4 (40%) is the accepted criterion for endolymphatic hydrops in Meniere's disease. The summating potential reflects distortion of basilar membrane motion caused by the distended membranous labyrinth, while the action potential represents synchronous auditory nerve firing. An elevated SP/AP ratio is one of the few objective electrophysiological markers supporting the diagnosis of Meniere's disease, especially in atypical cases.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.