Training in VNG

Performing positional testing (VNG)

Introductory

10 mins

Video

29 November 2022

So now that we finished the Dix Hallpike, we're going to do the positional tests. And you'll notice that the patient is lying at an incline, a 30-degree incline. This is the same position that she would be in for the caloric testing, that's going to come later. So that's why she's in this position. In here, we're going to try to put her head in the center, and then we're going to put her head to the right and to the left. And we may even have to roll around her side.

Instructions

So we're going to see if we can provoke nystagmus in a specific position. Okay, so I'm going to get started to put the cover on, because this test is also done with the eyes open in the dark. And then her first position in the position test is supine, 30 degrees, head center. So she's just going to be sitting like this.

And I'm just going to use my remote control to start the software. And then the test defaults for 30 seconds. If there isn't any positional nystagmus happening, 30 seconds is a long time. So it's not like it's going to provoke a little bit later on. So after about 15 seconds, and if I don't see anything, I'm just going to continue on to the next head position.

Test procedure

So I'm going to turn her head. I'm just going to hit next and I'm going to turn her head to the right. And then we're going to do the same thing. So now 15 seconds or so. And if I don't see anything, I'm going to stop the test. If I did see nystagmus, I would continue on for that next 15 seconds. She doesn't have any nystagmus in this position, but we're going to kind of pretend as if she did.

And if she did have nystagmus, then we would want to stop this test and open up her body to the right sub test. So here we go. So we selected the body to the right. And so now my instructions to her. This is a little awkward for the patient, so you really want to kind of help them through and make them feel comfortable doing this. So what I'm going to ask her to do is to tuck her right arm underneath, and she's gonna come up on her right leg and her right arm. And then I'll usually hold the head here. Now holding her head into position.

She's laying down on the side, but I'm kind of here for support just to let her know that I'm here. Remember, she's in the dark, and now she's laying on her side, she might even be dizzy. So she might be a little bit disoriented. So I'm just here for moral support, kind of bracing her head for her. And then we'll just let it run its course it only has five more seconds. And then I'm going to bring her back to center and then we're gonna go to the left.

Okay, so now it's coming back to the center. I'm gonna let her relax for a second. Okay. All right. And then first thing we're going to do is roll her head to the left now. So just roll your head to the left. And then we'll start the test. And again, looking at the screen to see if there's any position-evoked nystagmus with her head to the left. I don't see any, so I can go ahead and stop. Again. If there was nystagmus here, I could roll her to the left side like we did to the right side. But since there isn't any nystagmus, we can just be done with the test and bring her back to the center.

And now she's finished.

Abnormal positional test

This is an example of an abnormal positional test. And we can see here that when the patient was just supine, so lying in the chair, that 30-degree angle, they didn't have any noticeable nystagmus. When I rolled her head to the right, we see three degrees of nystagmus. So there's some nystagmus there, it's not real big, it's not significant.

When rolling the head to the left, you can see that the nystagmus was going all the way up to 16 degrees per second. So this is a really nice definitive test for a left lateral canal BPPV because the nystagmus was is in both directions, but stronger when the head was rolled to the left.

Description

Positional testing is all about maintaining a certain head position with respect to gravity. As it is the head position and not the movement that we are interested in, the movements to each position should be slow and the head position sustained for a time.

This video demonstrates how to perform positional testing with a patient.

Presenter

Dr Michelle Petrak

Dr. Michelle Petrak is the Director of Clinical Audiology for Interacoustics and is a licensed, practicing audiologist in the Chicago area. Dr. Petrak received her Doctorates in Electrophysiology and Biomolecular Electronics from Wayne State University in 1994 and her Masters in Audiology in 1989. Her special areas of expertise include vestibular and balance testing (VNG), electrophysiological techniques (ABR/ASSR/VEMP/ECoG) and pediatric audiology. Dr. Petrak is involved with product development, clinical evaluation testing, publishing, teaching and training on VNG and EP topics. In addition to being employed with Interacoustics, she is also a licensed and practicing audiologist at Northwest Speech and Hearing in Arlington Heights, IL. She continues to lecture extensively, nationally and internationally, and to publish articles in hearing industry journals.