Visual evoked potentials: Impact of age, gender, head size and BMI

Abstract

Background and Objectives: Pattern-reversal visual evoked potential (PRVEP) is an objective, sensitive and non-invasive neurophysiological test that can prove to be a useful clinical tool in investigating the physiology and pathophysiology of human visual system. A successful clinical application of the test, however, is not possible without the acquisition of a normative data adjusted to known confounding physiological variables. Hence, this study attempted to obtain PRVEP values in different age- groups and gender in healthy adults and also to find out the influence of head size and body mass index on PRVEP parameters. Methods: PRVEP was recorded in 52 healthy adults in the age-group of 18-70 years. PRVEP parameters were compared in different age-groups and gender using one way ANOVA. Head size and BMI were correlated with PRVEP parameters by Pearson correlation coefficient and the significance of difference analysed. Results: The study demonstrated statistically significant differences in mean P100 latency among various age-groups. Gender difference revealed statistical significant differences in both the PREVP parameters (P100 latency and N75-P100 amplitude). The correlation of head size and BMI with PRVEP parameters could not be found to be statistically significant. Conclusion: Clinical interpretation of PRVEP should be based on age and sex matched normal subjects besides standardizing the technical parameters of the laboratory. This study also suggests that endocrinal differences should be borne in mind besides the anatomical differences for gender variation in PRVEP-P100 latency. Key message: For adequacy and accuracy of neurophysiological tests like visual evoked potentials, normal values have to be adjusted for physiological variables. Every neurophysiology laboratory should have its own normative data based on age and gender. A possibility of the role of endocrinal influences should be borne in mind for gender variation in P100 latency.