Question
We do ABR testing on children unsedated. We have them watch a movie on a personal DVD player to keep them still and occupied. Is this a bad idea?
Answer
Successful collection of high quality, interpretable ABR data is influenced heavily by patient state. In an ideal world, every patient would cooperate and immediately lie down and fall asleep for their ABR test so that we could collect data with no myogenic noise, no artifacts and in the fastest possible time. But of course we must deal with reality. If natural sleep is not feasible and sedation is not an option, then use of any form of faux "anesthesia" that may help you get the job done, such as showing a favorite DVD, is a reasonable approach to try.
The caveats are as follows:
- It is advisable to keep control of the DVD player out of the hands of the child to avoid them fast-forwarding/rewinding to their favorite segment and to prevent them from manipulating the volume control. Isn't it amazing to see how adept very young children can be at using these controls?
- If you are allowing the child to listen to the soundtrack of the DVD in the unoccluded, non-test ear, the volume of the DVD should be kept to a minimum to avoid masking of the ABR stimulus in the test ear, especially if you are trying to obtain near-threshold responses.
- If you are using AC-powered TV/DVD equipment, be prepared to deal with the possibility of electrical artifact interfering with ABR data collection. A battery-powered device is desirable to avoid that issue.
- Realize that the data may contain more noise since the child is awake. You may need to alter the test procedure to reduce the noise and increase your confidence in the response. Consider averaging more sweeps than you would with a sleeping child. Or, if your ABR equipment has a means of displaying residual noise in the recording and/or averaging until some residual noise criterion is met, consider using those tools.
- Interpret your data with caution. Since these aren't ideal test conditions and you are likely to have higher residual noise in the ABR than you would with a sleeping child, you should interpret your data carefully. Be sure that the ABR is reproducible. Keep in mind that failure to achieve reliable ABR responses could merely reflect the possibility that high myogenic noise is overwhelming a low amplitude ABR rather than indicating the presence of an elevated ABR threshold.