Measuring the balance system beyond what you can see.
What are VEMPs and how do they work?
Vestibular Evoked Myogenic Potentials (VEMPs) assess the function of the otolith organs in the inner ear, which are responsible for detecting gravity and linear movement. This information is essential for maintaining balance, stable vision, and awareness of head position. The otolith organs consist of the saccule and the utricle. The saccule is primarily sensitive to vertical (up–down) movement and gravitational forces, while the utricle mainly detects horizontal (forward–back) movement and head position changes in the horizontal plane.
There are two main types of VEMP tests:
oVEMP (ocular VEMP) assesses utricle function and the pathway to the eye muscles, helping evaluate reflexes that contribute to visual stability during movement.
cVEMP (cervical VEMP) assesses saccule function and the pathway to the neck muscles, helping evaluate reflexes involved in head and postural control.
Together, these tests provide valuable information about parts of the vestibular system that are not assessed by more common tests like semicircular canal function, offering a more complete picture of inner ear balance function.
Results
These tests help us determine not only which ear is affected, but also which specific part of the vestibular system is involved.
For example, cVEMP and oVEMP results can indicate whether the dysfunction lies in the saccule or utricle, and whether the superior or inferior vestibular nerve pathways are affected. This level of detail helps “localise” the problem within the inner ear.
When VEMP results are interpreted alongside other vestibular tests, they provide a more complete picture of how the entire balance system is functioning. This combined approach improves diagnostic accuracy and helps differentiate between conditions that may present with similar symptoms. VEMPs can be particularity useful in diagnosing rare inner ear conditions such as superior canal dehiscence.
Management
The otolith organs help maintain upright posture and stability by detecting gravity and linear movement, allowing the body to make rapid, automatic adjustments to changes in head position. They contribute to reflex pathways that help stabilise the head, coordinate eye movements, and support postural control, so you can stay balanced when standing, walking, or changing direction.
When otolith function is reduced, these signals become less accurate. This can lead to unsteadiness, difficulty with balance in low-light or uneven environments, and reduced ability to respond quickly to shifts in position. As a result, otolith dysfunction has been associated with an increased risk of falls, particularly in older adults.
Identifying this impairment is important, as it allows for more targeted vestibular rehabilitation. Therapy can then focus on improving balance, enhancing gaze and postural stability, and developing compensatory strategies, helping to reduce symptoms and lower the risk of falls.
Summary
- Non-invasive
- Quick
- Provide localising information
VEMPs detect dysfunction in parts of the balance system that may not be identified with other vestibular tests, providing a more complete assessment of inner ear function.
