Question
I’m going to start performing cVEMP testing. Can I use a binaural/bilateral procedure?
Answer
Dr. Kamran Barin: When performing Cervical Vestibular Evoked Myogenic Potentials or cVEMP, using a binaural or bilateral procedure is not recommended for clinical decision making.
The reason is related to the crossover effect where some of the response from one side shows up in testing of the other side. For example, let’s assume we are able to measure VEMPs perfectly and the response from the right side is 100 microvolt and from the left is 30 microvolt. The asymmetry ratio (AR) is:
AR = (100-30)/(100+30) = 54%
In real testing, let’s assume that there is a crossover effect and 20% of the response from one side shows up on the other side. So the responses in binaural testing will be:
Right = response from right + 20% of response from left = 100 + 0.2*30 =100 + 6 = 106 microvolt
Left = response from left + 20% of response from right = 30 + 0.2*100 = 30 + 20 = 50 microvolt
AR = (106 – 50)/(106 + 50) = 36%
So, the asymmetry is underestimated. This does not happen with monaural testing because there is no input to the other side; it only happens with binaural testing when there is a difference between right and left responses.
Further resources and information:
- Courses: 3-day course, US: 16th Annual VNG/ENG course - hosted by Drs. Kamran Barin and Kristen Janky (up to 2.1 Tier 1 AAA CEUs, October 2016); 2-day course, Canada: Revolutionize Vestibular Testing - hosted by Drs. Kamran Barin and Kristen Janky (1.4 Tier 1 AAA CEUs, May 2016)
- Webinar: Vestibular Evoked Myogenic Potentials (VEMP) - How Do I Get Started?
- Interview: Practical Benefits to Adding VEMP Testing to Your Practice
- Ask the Expert: Why is FDA Clearance of VEMP Testing Important to Balance Care Today?
- Ask the Expert: What is VEMP and Why is it Important?
- Tools and tips: www.audiologysystems.com/vestibulartesting
