Advanced Diagnostic Tests Help Clinicians Assess Dizziness, Vestibular System

by Jennifer Fink •

VEMP response typically fades with age; in fact, as many as forty percent of people over the age of 60 may not have a cVEMP response, while a quarter will lack an oVEMP response; however, research suggests that adjusting the increasing the frequency may induce a better VEMP response in older adults (Ear Hear. 2013; 34:e65-e73).

At present, the primary application of VEMP is to rule out superior semicircular canal dehiscence (SSCD) syndrome. Patients with SSCD usually have a lower-than-normal threshold for the VEMP response. Recent research suggests that oVEMP amplitudes in response to sound are superior to cVEMP thresholds in the diagnosis of SSCD (Otol Neurotol. 2013;34:121-126).

“In my practice, I use this test as part of my evaluation when I suspect a third window lesion,” Dr. Adams said. “At this point, it’s very clear that VEMP testing helps with superior canal dehiscence syndrome, but we’re just now getting more information to figure out how it will be most helpful in other disorders.”

Because VEMP assesses the function of the otoliths, Dr. Janky, Dr. McCaslin, and others believe it will complement, instead of supplant, other balance tests. “We’ve started adding the VEMP test to our initial battery of testing because a VEMP and VNG look at two separate parts of the ear,” Dr. Janky said.

VEMP testing is not yet FDA approved and at least some insurance companies consider VEMP testing experimental and investigational. Some clinicians are having luck billing VEMP testing as an unspecified code.

The Future of Balance Disorder Testing

“We’re at a stage with these tests where the tests are helping us understand the normal function of the vestibular system. As the tests are developed, we learn more about the vestibular system and how it functions in disease, and then we learn more about how to use the tests,” Dr. Adams said.

More research is needed to better understand what vHIT and VEMP testing reveals; it is hoped that increased understanding of the vestibular system will also lead to more precise diagnosis and treatment.

“The clinical utility of these tests is still being worked out,” Dr. McCaslin said. Clinicians interested in using vHIT and VEMP testing in their practices are advised to stay up on the current literature. “You need to understand what the best practices are at this time, because that’s changing in real time.”

Jennifer Fink is a freelance medical writer based in Wisconsin.