What do cVEMP and oVEMP primarily assess?

• A. cVEMP reflects saccular and inferior vestibular nerve function; oVEMP reflects utricular and superior vestibular nerve function
• B. cVEMP reflects utricular function; oVEMP reflects saccular function
• C. cVEMP reflects cochlear function; oVEMP reflects vestibular nerve function
• D. cVEMP reflects semicircular canal function; oVEMP reflects cochlear function

Answer: (A)

cVEMP and oVEMP test the otolith-vestibular pathways, mapping to the two otolithic organs and their nerve connections. The saccule communicates mainly through the inferior vestibular nerve, and cVEMP activity reflects that saccular/inferior-vestibular-nerve pathway. The utricle communicates mainly through the superior vestibular nerve, and oVEMP activity reflects utricular/superior-vestibular-nerve function. In practice, cVEMP is recorded from the sternocleidomastoid muscle in response to sound or vibration, with a characteristic P13-N23 waveform, while oVEMP is recorded from extraocular muscles (often the inferior oblique) and shows a typical N10-P15 waveform.

This is why the statement about cVEMP indicating saccular and inferior nerve function and oVEMP indicating utricular and superior nerve function is the best fit. Cochlear function or semicircular canal function is not what these evoked potentials primarily assess, which is why the other descriptions don’t align with how these tests map to the vestibular system.