Optimization of the pattern visual evoked potential (VEP) in the visually-normal and mild traumatic brain injury (mTBI) populations.

PRIMARY OBJECTIVE The purpose of this study was to assess the effect of check size (CS) and contrast (C) on VEP amplitude and latency in visually-normal (VN) and in mild traumatic brain injury (mTBI) adults to develop an optimized test protocol in each group. RESEARCH DESIGN AND METHODS Subjects were comprised of VN (n = 19) and individuals with mTBI (n = 16). Full-field, pattern VEP testing was employed with three different CSs (10, 20 and 40 min arc) and at two C levels (20 and 85%). RESULTS There was a significant effect of CS and C on the VEP amplitude and latency in both groups. The 20 min arc CS at both contrast levels produced the largest VEP amplitude, in conjunction with normative latency values, in both populations. There was a significant differential effect of CS and C on VEP responses in the visually symptomatic vs. asymptomatic mTBI sub-groups. A significant correlation was found between time since their most recent brain injury and VEP amplitude for the 20 min arc CS at low contrast. CONCLUSIONS Use of the 20 min arc CS at both contrast levels represents an optimized clinical VEP test protocol in both the VN and mTBI groups. This protocol is rapid, high yield, and targeted for each diagnostic group.