Faster and more sensitive VEP recording in children

In the difficult-to-test paediatric population, shorter test procedures are desirable. This study investigates whether Laplacian analysis of a three occipital-electrode montage detects steady-state VEPs (ssVEPs) more often or faster in children than a conventional montage, and if so, in which age groups.

Steady-state VEPs (7.78 reversals/s; checkerboard stimulus) to various checksizes (60-3', 0.07-14 cpd equivalent) were recorded from 80 normal children aged from 1 month to 13 years and 19 adults. Active occipital electrodes were placed at Oz and symmetrically either side at 15% of the subject's half-head circumference (right occipital and left occipital, RO and LO). The Laplacian analysis used 2Oz-(RO+LO) instead of the conventional Oz-Fz. Fourier analysis and a circular T2 statistic was used to determine VEP detection time (DT). The number of responses detected overall by each analysis method and the effects of age and checksize on DT differences between analysis methods were investigated.

The Laplacian analysis detected more VEPs than the conventional Oz-Fz (95 versus 84%, p = 0.001) in children's age groups. The Laplacian analysis also provided faster response detection to 3' checks in all subjects over the age of five, and to 6' and 9' in 7-9-year-olds.

A Laplacian analysis offers increased sensitivity and faster VEP detection over conventional (Oz-Fz) recording in children over five for threshold-sized VEPs. Simultaneous use of both conventional (Oz-Fz) VEP recording and a Laplacian analysis in all patient ages is likely to give faster, more accurate VEP assessments.