Effect of reference point on visual evoked potentials: clinical relevance.

Area of Science:

• Neuroscience
• Ophthalmology
• Clinical Electrophysiology

Background:

• Visual evoked potential (VEP) recordings are crucial for assessing the visual pathway.
• Current clinical practice often uses mid-occipital recording referenced to the vertex or mid-frontal region.
• Potential interpretive errors can arise from non-ideal reference electrode placement.

Purpose of the Study:

• To evaluate the utility of using linked mastoids as a reference electrode in VEP recordings.
• To compare the diagnostic yield and technical quality of VEPs recorded with linked mastoid versus conventional references.
• To determine if linked mastoid referencing can reduce interpretive errors in VEP analysis.

Main Methods:

• Simultaneous VEP recordings were performed using both conventional (mid-occipital to vertex/mid-frontal) and linked mastoid reference montages.
• VEPs were analyzed for diagnostic yield, waveform clarity, and technical adequacy.
• Factors contributing to technically inadequate recordings, such as P100 amplitude and muscle artifact, were assessed.

Main Results:

• Both recording derivations demonstrated similar diagnostic yield.
• The linked mastoid reference provided a greater number of technically inadequate recordings.
• Smaller P100 component size and increased muscle artifact contamination were observed with the linked mastoid reference.

Conclusions:

• Linked mastoid referencing can help avoid interpretive errors by using a more inactive reference point.
• Despite similar diagnostic yield, the linked mastoid method may require careful technical execution to mitigate artifact.
• Simultaneous recording with multiple derivations is recommended for clarifying ambiguous VEP waveforms.