Rates of Reliable Multifocal Visual Evoked Potential Waveforms: Comparison Between Multiple Sclerosis and Neuromyelitis Optica Patients

Abstract

Purpose: To compare the rates of reliable multifocal visual evoked potentials (mfVEP) between patients with multiple sclerosis (MS) and neuromyelitis optica (NMO).

Methods: Patients with MS (8 subjects, 16 eyes, 37±9.7 years old) and with NMO (11 subjects, 19 eyes, 36.1±11.8 years old) were studied with biomicroscopy, fundoscopy, visual acuity measurements, and visual electrophysiology (mfVEP). mfVEP was recorded using Veris System 6.010, with 60 black-and-white sectors. For each mfVEP waveform, the signal-to-noise ratio (SNR) was estimated. mfVEP waveforms were considered reliable when the SNR was higher than 1.395. In addition, the rates of reliable mfVEP waveforms were quantified as the ratio of the number of reliable waveforms/total number of sectors for six areas of the same eccentricity (from R1 in the inner visual field to R6 in the outer visual field) and at the entire visual field. The results of patient groups were compared to each other and to an age- and gender-matched control group using the binomial test (α=0.05).

Results: Optic neuritis (ON) was present in 5/16 eyes from MS patients and 8/19 eyes from NMO patients. The rates of reliable mfVEP for the controls were higher than those obtained for MS with or without ON and NMO with ON in R1-R5. In R6, the rate for controls was higher than the rate for all other patient groups. The rate of reliable mfVEP for controls were higher than that obtained for MS with or without ON and NMO with ON (p<0.01) in R1-R5. In R6, the rate for controls was higher than the rate for all other patient groups. The rate of reliable mfVEP for the NMO group was higher than the rate for the MS group despite the presence of ON. The rate of reliable waveforms for the MS group without ON was higher than that for the MS and ON groups (p<0.01), and the rate from the NMO without ON was higher than that for the NMO group with ON for all the analyzed areas.

Conclusions: The rate of mfVEP waveform reliability was lower in MS patients than in controls and NMO patients, and the presence of ON decreased significantly the performance of MS and NMO patients to generate reliable mfVEP waveforms.

Keywords: 613 neuro-ophthalmology: optic nerve • 507 electrophysiology: clinical