Information on Vestibular Evoked Myogenic Potentials
Vestibular Evoked Myogenic Potentials (VEMPs) in the assessment of inner ear dizziness
This test assesses the inner ear sensitivity to linear motion or tilt and is performed when lying partially inclined on a plinth while lifting your head off the pillow. This action activates neck muscles, while at the same time a clicking sound is applied briefly to one ear.
The clicking sound is detected by a structure known as the saccule within the inner ear, which is sensitive to linear motion/tilt. The saccule then sends a message or a nerve impulse to neck muscles. This message allows for any subsequent adjustment in posture. The muscle response is called a vestibular evoked muscle potential or myogenic potential.
The nerve supplying the inner ear has both an inferior division, supplying the saccule (sensitive to linear motion) and a superior division, supplying the 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 and is also used in assessing dizziness.