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L. K. Grover, T. M. Grippo, A. Wenick, E. B. Yang, Q. Ghadiali, M. M. Behrens, J. G. Odel, V. C. Greenstein, D. C. Hood; A Comparison Between Multifocal and Conventional VEP Latency Changes Secondary to Optic Neuritis. Invest. Ophthalmol. Vis. Sci. 2007;48(13):912.
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The multifocal visual evoked potential (mfVEP) can be used to assess local changes in latency  and has been suggested as an alternative to the conventional VEP (cVEP) for detecting damage secondary to multiple sclerosis (MS).[2-4] Here the two methods are compared for patients referred for VEP testing to rule out optic neuritis (ON)/MS.
15 patients referred by neuro-ophthalmologists to rule out possible ON/MS in 18 eyes were tested. mfVEPs and cVEPs were obtained from 29 eyes of the patients and from 40 eyes of normal controls. For the mfVEP, the display was a "standard" 60 sector, pattern-reversal dartboard array, 44.5 deg. in diameter. The mfVEPs were obtained using the VERIS system (EDI, San Mateo) with three channels of recording; responses were analyzed with custom software as previously described. [1,5] Monocular cVEPs were obtained using a checkerboard stimulus with check sizes of 15' and 60'. Recordings were obtained between Oz and Fz. For the cVEP, the latency of P100 was measured and for the mfVEP, the mean latency of all responses satisfying a minimum SNR was obtained. Each was considered abnormal if it fell outside the range of the 40 normal eyes. In addition, the probability plots for the mfVEP latency were analyzed for significant clusters.
Of the 18 eyes tested to rule out ON/MS, 44.4% (cVEP-15'), 66.7% (cVEP-60'), 72.2% (mfVEP- latency) and 77.8% (mfVEP-cluster) were classified as abnormal. Two eyes were classified as normal on the cVEP-60', but abnormal on the mfVEP tests. In both cases, the diagnosis of MS was confirmed on other tests, and in both cases, the delays on the mfVEP were seen in only part of the visual field.
The cVEP classified almost as many eyes (12 vs 14) as abnormal as did the mfVEP. On the other hand, as expected, some eyes will appear normal on the cVEP, but abnormal on mfVEP especially if the damage is relatively local.[2,3] To rule out ON/MS, a cVEP will often be sufficient. However, if the cVEP is normal, a mfVEP should be performed. 1. Hood et al, 2004, Doc Ophthal; 2. Hood, Odel & Zhang (2000) IOVS; 3. Hood, Odel, Winn 2003, JNO; 4. Ruseckaite et al (2005 Ann Neurol. 5. Hood & Greenstein, 2003, PRER. Supported by Grant NIH RO1-EY02115
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