Ocular VEMP - Protocol & Parameter Selection

This video guides clinicians on the selection of a protocol and parameters to record the ocular VEMP.

Transcript

Darren Whelan: I'd like just to take a moment to have a look at the oVEMP parameters.

So in the Eclipse, we have a default oVEMP protocol.

But here we can select our setup button here, which is our temporary setup, just to take a look at a few more details in relation to the protocol that we're utilizing.

So the first thing I'd like to draw your attention to is the stimulus type.

So we have tone burst, chirp stimuli and click.

Now in the literature, there's been a lot of publications on tone bursts.

But a more recent article in 2023, compared a lot of the stimulus types with the chirp and found that the chirp actually gives larger responses for both cervical and ocular VEMP.

So we'll pick a narrowband CE chirp.

So that's our stimulus selected, we have our frequency already here at 500 hertz.

And we know that that's the optimal frequency for assessing both cervical and ocular VEMPs.

So as we're doing an ocular VEMP, select that, and then we've got the stimulus ear transducer.

So if we're using air conduction, we can use inserts or headphones, and for bone conduction, we can select the bone conductor transducer as well.

Now the other thing to take a look at is the number of stimuli that we can record in one epoch.

So here we can see we've got this set to 500, much higher than you would see in a cervical VEMP measurement, and because sometimes we have a little bit more noise in the smaller ocular VEMP measurement, so we want to run for a little bit more.

Now it might be that we stopped the recording at 200 or 300 stimuli, maybe even less than that.

But it gives us the option to carry on recording for as long as we need so that we're confident that the response is present or absent.

Now, the other part that you will see here, has been referred to in the cervical VEMP protocols.

So these are all of the EMG controlled stimulus recording options, monitors and scaling.

Now in the ocular VEMP, this is a much smaller response.

The EMG is a lot smaller because the muscle is smaller.

But the other key parameter that we need to think about is that this is not an EMG controlled amplitude response, so we don't actually need to utilize any of these particular settings in this protocol.

So now that we have everything selected, my insert, my 500 hertz, my narrowband CE chirp in the Eclipse.

I'm quite happy now to press OK and be ready for my protocol to assess the ocular VEMPs.