Introduction
What VEMPs measure, why they matter, and how they fit into the wider work-up of the dizzy patient.
What is a VEMP?
A vestibular evoked myogenic potential — a VEMP — is a small electrical response recorded from a muscle when a loud sound or vibration stimulates the inner ear. The two clinical variants test two different organs:
- cVEMP (cervical) — recorded from the sternocleidomastoid neck muscle, tests the saccule and the inferior vestibular nerve.
- oVEMP (ocular) — recorded from a muscle under the eye, tests the utricle and the superior vestibular nerve.
VEMPs are the only routine clinical test of the otolith organs — the parts of the inner ear that sense gravity and linear acceleration. Calorics and the head-impulse test do not assess them.
Why VEMPs matter
Conventional vestibular testing — caloric irrigation, head-impulse testing, rotary chair — interrogates the horizontal semicircular canal and its superior-nerve afferent. A patient with isolated saccular dysfunction or with an inferior-division neuritis can have entirely normal results and yet present with persistent vestibular symptoms.
VEMPs filled that gap. Together they make topographic diagnosis possible — distinguishing superior from inferior vestibular neuritis, identifying a third-window pathology like superior canal dehiscence, and confirming utricular involvement in conditions such as BPPV.[3,5]
A brief history
Tullio's 1929 demonstration that sound could induce vestibular responses in pigeons set the stage; Bickford and colleagues recorded sound-evoked potentials from the inion in the 1960s; but the modern cVEMP dates from Colebatch, Halmagyi and Skuse's 1994 description of a click-evoked vestibulocollic reflex.[10]
Rosengren and colleagues described the ocular VEMP in 2005, using bone-conducted stimuli at Fz to elicit a contralateral inferior-oblique excitatory response.[6] Subsequent decades refined the stimulus (500 Hz tone-burst standard; high-frequency tone bursts for third-window pathology), the montage, and the EMG-correction procedures now central to clinical reporting.[5,12]
Place in the work-up
The 2017 AAN guideline rates evidence for VEMP as Level B (substantively aids diagnosis) for superior canal dehiscence — its strongest single endorsement — and Level C-negative for routine use in Ménière's disease, vestibular migraine, and BPPV.[1] Even where dedicated guideline support is weaker, VEMP retains a role in topographic localisation that no other test can replicate.