4242 VEP responses to achromatic and chromatic stimuli in sharp and blurred vision

The pattern VEP is frequently abnormal in multiple sclerosis. In this disease the VEP latency is prolonged and the amplitude is reduced. The use of the VEP amplitude in diagnosis is limited because of the large interand intrasubject variability and low signal-to-noise ratio (SNR). Goal of this project is to improve the SNR of VEP’s with alternative averaging procedures, and to investigate whether VEP latency jitter and SNR are supplementary parameters in the diagnosis of multiple sclerosis. I!,laka The latency variability of “single” VEP responses is estimated and corrected by means of a spectral phase difference (SPD) method. The achieved improvement is expressed by the SNR of the VEP ensemble. li!cuks In a comparitive study of a control group consisting of 29 healthy subjects and a group of 30 patients we found that in the original VEP data of the multiple sclerosis group the latency jitter was significantly (p<O.OS) higher, and the SNR significantly @<0.05) lower. Correction of latency jitter resulted in a small increase of the SNR in the control group, and a significant increase in the MS group. Conclusions The developed jitter correction method resulted in better VEP estimates in patients of the MS group, and provided the clinician with two additional VEP parameters: signal-to-noise ratio and latency jitter. Further research is necessary to investigate whether this can lead to an increased diagnostic power of visual evoked potentials.