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Improved characterization of visual evoked potentials in multiple sclerosis by topographic analysis.

Hardmeier M, Hatz F, Naegelin Y, Hight D, Schindler C, Kappos L, Seeck M, Michel CM, Fuhr P - Brain Topogr (2013)

Bottom Line: TVEP was compared to conventional analysis (cVEP) with respect to reliability in HC, validity using descriptors of logistic regression models, and sensitivity derived from receiver operating characteristics curves.HC) and hON were more favorable using tVEP- versus cVEP-predictors.In combination with other EP modalities, tVEP may improve the monitoring of disease course in MS.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Hospital of the University of Basel, Petersgraben 4, 4031, Basel, Switzerland, martin.hardmeier@usb.ch.

ABSTRACT
In multiple sclerosis (MS), the combination of visual, somatosensory and motor evoked potentials (EP) has been shown to be highly correlated with the Expanded Disability Severity Scale (EDSS) and to predict the disease course. In the present study, we explored whether the significance of the visual EP (VEP) can be improved with multichannel recordings (204 electrodes) and topographic analysis (tVEP). VEPs were analyzed in 83 MS patients (median EDSS 2.0; 52 % with history of optic neuritis; hON) and 47 healthy controls (HC). TVEP components were automatically defined on the basis of spatial similarity between the scalp potential fields (topographic maps) of single subjects' VEPs and reference maps generated from HC. Non-ambiguous measures of latency, amplitude and configuration were derived from the maps reflecting the P100 component. TVEP was compared to conventional analysis (cVEP) with respect to reliability in HC, validity using descriptors of logistic regression models, and sensitivity derived from receiver operating characteristics curves. In tVEP, reliability tended to be higher for measurement of amplitude (p = 0.06). Regression models on diagnosis (MS vs. HC) and hON were more favorable using tVEP- versus cVEP-predictors. Sensitivity was increased in tVEP versus cVEP: 72 % versus 60 % for diagnosis, and 88 % versus 77 % for hON. The advantage of tVEP was most pronounced in pathological VEPs, in which cVEPs were often ambiguous. TVEP is a reliable, valid, and sensitive method of objectively quantifying pathological VEP in particular. In combination with other EP modalities, tVEP may improve the monitoring of disease course in MS.

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Examples of single VEPs in a healthy subject (a) and two patients (b, c); upper panel: conventional VEP; middle panel: butterfly plots with topographically defined, color-coded EP components; lower panel: corresponding time course of GFP with respective color-coding. (GFP global field power, uV microVolt; red lines: time window for quantitative analysis). a Same healthy subjects as in Fig. 2: in addition to conventional waveform and butterfly plot with color-coded EP-components (see Fig. 2), the time course of the GFP and the time window for analysis is shown (lower panel). A wider time window would have falsely given the late peak as the latency of the P100 component. b MS patient with positive history of ON, visual acuity 0.5, EDSS 4.0: conventional waveform shows a small and a high positive peak at 95 and 160 ms, latency and amplitude measurement is ambiguous; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S1) is highest to the “P100”-reference; for analysis, the latency at the end of the time window is used (tLat = 150 ms; replacement procedure 3). c MS patient with positive history of ON, visual acuity 0.5, EDSS 2.0: conventional waveform shows a shallow peak at 103 ms; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S2) is highest to the “N75”-reference; for analysis, the most pathological values of latency, amplitude and configuration (tLat, tAmp, tAUC and tFit) measured in the sample are used (replacement procedure 2) (Color figure online)
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Fig3: Examples of single VEPs in a healthy subject (a) and two patients (b, c); upper panel: conventional VEP; middle panel: butterfly plots with topographically defined, color-coded EP components; lower panel: corresponding time course of GFP with respective color-coding. (GFP global field power, uV microVolt; red lines: time window for quantitative analysis). a Same healthy subjects as in Fig. 2: in addition to conventional waveform and butterfly plot with color-coded EP-components (see Fig. 2), the time course of the GFP and the time window for analysis is shown (lower panel). A wider time window would have falsely given the late peak as the latency of the P100 component. b MS patient with positive history of ON, visual acuity 0.5, EDSS 4.0: conventional waveform shows a small and a high positive peak at 95 and 160 ms, latency and amplitude measurement is ambiguous; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S1) is highest to the “P100”-reference; for analysis, the latency at the end of the time window is used (tLat = 150 ms; replacement procedure 3). c MS patient with positive history of ON, visual acuity 0.5, EDSS 2.0: conventional waveform shows a shallow peak at 103 ms; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S2) is highest to the “N75”-reference; for analysis, the most pathological values of latency, amplitude and configuration (tLat, tAmp, tAUC and tFit) measured in the sample are used (replacement procedure 2) (Color figure online)

Mentions: Figure 2 displays the fitting procedure applied to an individual VEP of a healthy subject. From the butterfly plot (Fig. 2b) the individual time course of topographic maps is derived (Fig. 2c), and each time point of the butterfly plot is color-coded (Fig. 2e) according to the magnitude of the spatial correlation of the corresponding topographic map to one of the reference maps (Fig. 2d). In order to quantify the field strength of the VEP at each time point, the global field power (GFP) was used (Lehmann and Skrandies 1980). GFP is defined as the standard deviation of the mean amplitude over all electrodes at a single time point. Figure 3a shows in the same healthy subject as in Fig. 2 the GFP time course (lower panel) derived from the butterfly plot (middle panel) with corresponding color-coding. Supplemental figures (Fig. S1 and S2) depict the fitting procedure including the time series of topographic maps for the two MS subjects shown in Fig. 3b, c.Fig. 2


Improved characterization of visual evoked potentials in multiple sclerosis by topographic analysis.

Hardmeier M, Hatz F, Naegelin Y, Hight D, Schindler C, Kappos L, Seeck M, Michel CM, Fuhr P - Brain Topogr (2013)

Examples of single VEPs in a healthy subject (a) and two patients (b, c); upper panel: conventional VEP; middle panel: butterfly plots with topographically defined, color-coded EP components; lower panel: corresponding time course of GFP with respective color-coding. (GFP global field power, uV microVolt; red lines: time window for quantitative analysis). a Same healthy subjects as in Fig. 2: in addition to conventional waveform and butterfly plot with color-coded EP-components (see Fig. 2), the time course of the GFP and the time window for analysis is shown (lower panel). A wider time window would have falsely given the late peak as the latency of the P100 component. b MS patient with positive history of ON, visual acuity 0.5, EDSS 4.0: conventional waveform shows a small and a high positive peak at 95 and 160 ms, latency and amplitude measurement is ambiguous; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S1) is highest to the “P100”-reference; for analysis, the latency at the end of the time window is used (tLat = 150 ms; replacement procedure 3). c MS patient with positive history of ON, visual acuity 0.5, EDSS 2.0: conventional waveform shows a shallow peak at 103 ms; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S2) is highest to the “N75”-reference; for analysis, the most pathological values of latency, amplitude and configuration (tLat, tAmp, tAUC and tFit) measured in the sample are used (replacement procedure 2) (Color figure online)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3921459&req=5

Fig3: Examples of single VEPs in a healthy subject (a) and two patients (b, c); upper panel: conventional VEP; middle panel: butterfly plots with topographically defined, color-coded EP components; lower panel: corresponding time course of GFP with respective color-coding. (GFP global field power, uV microVolt; red lines: time window for quantitative analysis). a Same healthy subjects as in Fig. 2: in addition to conventional waveform and butterfly plot with color-coded EP-components (see Fig. 2), the time course of the GFP and the time window for analysis is shown (lower panel). A wider time window would have falsely given the late peak as the latency of the P100 component. b MS patient with positive history of ON, visual acuity 0.5, EDSS 4.0: conventional waveform shows a small and a high positive peak at 95 and 160 ms, latency and amplitude measurement is ambiguous; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S1) is highest to the “P100”-reference; for analysis, the latency at the end of the time window is used (tLat = 150 ms; replacement procedure 3). c MS patient with positive history of ON, visual acuity 0.5, EDSS 2.0: conventional waveform shows a shallow peak at 103 ms; the color-coding of the butterfly plot and the time course of GFP reflect the fact that spatial similarity of topographic maps (see Fig. S2) is highest to the “N75”-reference; for analysis, the most pathological values of latency, amplitude and configuration (tLat, tAmp, tAUC and tFit) measured in the sample are used (replacement procedure 2) (Color figure online)
Mentions: Figure 2 displays the fitting procedure applied to an individual VEP of a healthy subject. From the butterfly plot (Fig. 2b) the individual time course of topographic maps is derived (Fig. 2c), and each time point of the butterfly plot is color-coded (Fig. 2e) according to the magnitude of the spatial correlation of the corresponding topographic map to one of the reference maps (Fig. 2d). In order to quantify the field strength of the VEP at each time point, the global field power (GFP) was used (Lehmann and Skrandies 1980). GFP is defined as the standard deviation of the mean amplitude over all electrodes at a single time point. Figure 3a shows in the same healthy subject as in Fig. 2 the GFP time course (lower panel) derived from the butterfly plot (middle panel) with corresponding color-coding. Supplemental figures (Fig. S1 and S2) depict the fitting procedure including the time series of topographic maps for the two MS subjects shown in Fig. 3b, c.Fig. 2

Bottom Line: TVEP was compared to conventional analysis (cVEP) with respect to reliability in HC, validity using descriptors of logistic regression models, and sensitivity derived from receiver operating characteristics curves.HC) and hON were more favorable using tVEP- versus cVEP-predictors.In combination with other EP modalities, tVEP may improve the monitoring of disease course in MS.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Hospital of the University of Basel, Petersgraben 4, 4031, Basel, Switzerland, martin.hardmeier@usb.ch.

ABSTRACT
In multiple sclerosis (MS), the combination of visual, somatosensory and motor evoked potentials (EP) has been shown to be highly correlated with the Expanded Disability Severity Scale (EDSS) and to predict the disease course. In the present study, we explored whether the significance of the visual EP (VEP) can be improved with multichannel recordings (204 electrodes) and topographic analysis (tVEP). VEPs were analyzed in 83 MS patients (median EDSS 2.0; 52 % with history of optic neuritis; hON) and 47 healthy controls (HC). TVEP components were automatically defined on the basis of spatial similarity between the scalp potential fields (topographic maps) of single subjects' VEPs and reference maps generated from HC. Non-ambiguous measures of latency, amplitude and configuration were derived from the maps reflecting the P100 component. TVEP was compared to conventional analysis (cVEP) with respect to reliability in HC, validity using descriptors of logistic regression models, and sensitivity derived from receiver operating characteristics curves. In tVEP, reliability tended to be higher for measurement of amplitude (p = 0.06). Regression models on diagnosis (MS vs. HC) and hON were more favorable using tVEP- versus cVEP-predictors. Sensitivity was increased in tVEP versus cVEP: 72 % versus 60 % for diagnosis, and 88 % versus 77 % for hON. The advantage of tVEP was most pronounced in pathological VEPs, in which cVEPs were often ambiguous. TVEP is a reliable, valid, and sensitive method of objectively quantifying pathological VEP in particular. In combination with other EP modalities, tVEP may improve the monitoring of disease course in MS.

Show MeSH
Related in: MedlinePlus