How would results from the head impulse test change the clinical management of the patient?
Kamran Barin: A patient who comes in with vertigo, spontaneous nystagmus but no hearing loss would have been diagnosed with vestibular neuritis in the past after caloric testing because there was no other way of separating vestibular nerve abnormalities from the canal abnormalities. However, if you do head impulse testing and oVEMPs and cVEMPs together, for the first time, you can separate vestibular nerve abnormalities from canal abnormalities. Vascular issues are one of the underdiagnosed causes of dizziness that affect the inner ear. We have never been able to see those before. But now, with the addition of this group of tests, we can make a distinction between a nerve issue and a canal issue. The more likely cause of isolated canal abnormalities is what’s called a transient ischemic attack. These are the people who are at risk for later stroke. So if we simply diagnose them with vestibular neuritis, we are missing the bigger picture, which is that the patient is at risk for a stroke. That’s pretty serious.
Wendy Crumley-Welsh: The other thing we had an ENT point out to us was that the calorics are flawed, meaning you can have temperature effects. They’re really dependent on how well the tester is doing the test. There is variability from one clinic to the next clinic, so even though calorics are considered somewhat of a gold standard, they come with several issues. By adding the head impulse test, it gives you more information and helps you clarify a diagnosis in the case where there are issues with the calorics.
Kamran Barin: We aren’t suggesting that this is going to replace the caloric testing. We need more time, but it’s likely that in the future we could do away with the caloric testing if this test proves to be as sensitive as we believe it will be, or at least it can reduce the number of calorics we are performing now.
Wendy Crumley-Welsh: If you are interested in learning more about the head impulse test, we’re launching live seminars on how to perform the head impulse test starting in June so that the people interested in this device can learn about its clinical relevance and have a hands-on opportunity. The first course is part of a VNG/ENG course presented by Kamran on May 18th at The Allerton Hotel in Chicago. We will be adding more dates along the way. For more information or to pre-register, please visit www.otometrics.com/impulse. You may also visit the Otometrics Expo Page on AudiologyOnline.