VEMP Test (Vestibular Evoked Myogenic Potential)

VEMP testing measures reflex muscle responses to sound or vibration to assess otolith organ and vestibular nerve function. Cervical VEMP records sternocleidomastoid responses (saccule/inferior nerve); ocular VEMP records extraocular muscle responses (utricle/superior nerve). It’s noninvasive, uses surface electrodes and acoustic or vibration stimuli, and helps diagnose vestibular disorders like Meniere’s, vestibular neuritis, and superior canal dehiscence.

Normal VEMP shows reproducible bilateral responses with latencies within lab reference ranges (cVEMP: P13 ≈13 ms, N23 ≈23 ms; oVEMP: N10 ≈10 ms, P15 ≈15 ms) and low interaural amplitude asymmetry (typically <30–40%). Thresholds are within expected stimulus levels. Absent responses, delayed latencies, or high asymmetry suggest vestibular/saccular or inferior vestibular nerve dysfunction.

Vestibular evoked myogenic potentials (VEMPs) are electrophysiological tests that assess otolith organ and vestibular nerve function by recording muscle responses to brief loud acoustic, bone‑conducted, or vibratory stimuli. Cervical VEMP (cVEMP) records inhibitory potentials from the sternocleidomastoid reflecting saccular and inferior vestibular nerve integrity; ocular VEMP (oVEMP) records extraocular muscle responses reflecting utricular and superior vestibular pathway function (latency, amplitude).

VEMP interpretation: presence, latency, and amplitude/asymmetry are key. cVEMP tests saccule/inferior vestibular nerve; oVEMP tests utricle/superior nerve. Absent or markedly reduced response suggests vestibular end‑organ or nerve dysfunction. Significant interaural amplitude asymmetry (commonly >35–40%) or prolonged latencies indicate unilateral hypofunction or delayed conduction. Consider age, muscle activation and hearing status; correlate with clinical findings and imaging.

VEMP testing is usually not painful. Surface electrodes record muscle responses while brief, loud sounds or gentle skull taps stimulate the vestibular system; these stimuli can be startling and may cause brief discomfort, neck muscle tightness, or transient dizziness or tinnitus. Most people tolerate it well; any significant pain, prolonged symptoms, or recent ear surgery should be discussed with your clinician beforehand.

Vestibular testing begins with history and a physical exam, then eye- and head-movement checks (Dix–Hallpike, head-impulse). Tests include videonystagmography/electronystagmography to record eye movements, caloric testing (warm/cold air or water in the ear), rotary-chair and posturography for balance, and vestibular-evoked myogenic potentials. You’ll wear goggles, perform head and balance tasks, and may feel brief dizziness or nausea.