Uncrossed Asymmetry in Pattern Visual Evoked Potentials: A Reappraisal

Area of Science:

• Neuroscience
• Ophthalmology
• Diagnostic Imaging

Background:

• Retrochiasmal lesions can cause visual field defects.
• Accurate prediction of these lesions is crucial for timely intervention.
• Full-field pattern reversal visual evoked potentials (FF-PVEPs) assess the integrity of the visual pathway.

Purpose of the Study:

• To evaluate the utility of uncrossed asymmetry in FF-PVEPs for predicting retrochiasmal lesions.
• To determine the positive predictive value of FF-PVEPs in identifying these lesions.

Main Methods:

• Analyzed FF-PVEPs from 754 patients over 8 years, blinded to clinical data.
• Calculated interhemispheric amplitude ratios (N75-P100, P100-N145).
• Defined significant asymmetry as >50% amplitude difference, irrespective of the stimulated eye.

Main Results:

• Identified 11 patients (1.5%) with significant FF-PVEP asymmetry.
• Ten of these 11 patients (91% positive predictive value) had MRI-confirmed retrochiasmal lesions.
• Demonstrated a high accuracy in predicting retrochiasmal pathology.

Conclusions:

• Specified amplitude criteria in FF-PVEPs provide evidence for retrochiasmal lesions.
• Abnormal interhemispheric amplitude ratios in FF-PVEPs are an underrecognized diagnostic criterion.
• FF-PVEPs show promise as a non-invasive tool for predicting retrochiasmal lesions.