Information on Vestibular Evoked Myogenic Potentials
Vestibular evoked myogenic potential testing in the assessment of inner ear dizziness
Vestibular Evoked Myogenic Potentials (VEMPs)
The test is performed when lying partially inclined on a plinth while lifting your head off the pillow. This action activates the neck muscle, while at the same time the clicking sound is applied briefly to one ear.
This test assesses the inner ear sensitivity to linear motion or tilt. The test is performed by the transmission of a clicking sound via headphones to each ear. The sound waves are detected by a structure known as the saccule within the inner ear. This is sensitive to linear motion/tilt. The saccule sends a message to neck muscles as a result of this stimulus. The muscle response is called a vestibular evoked muscle potential or myogenic potential.
The saccule is about 3mm in length. The nerve supplying the inner ear has both an inferior division, supplying the saccule (sensitive to linear motion) and one of the semi-circular canals (posterior), while the superior division supplies the remaining semi-circular canals, sensitive to angular motion. Thus a vestibular evoked myogenic potential provides an independent measure of inner ear function, separate from that of caloric testing.