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© 1992 American Academy of Neurology Spatial frequency evoked visuograms in multiple sclerosisFrom the Department, of Neurology, Loyola University of Chicago and Hines Veterans Administration Hospital, Maywood, IL. We obtained steady-state visual evoked potentials (VEPs) to sinusoidal gratings alternating at 4 Hz with spatial frequencies varying from 0.5 to 8 cpd in 21 normal controls and 21 patients with multiple sclerosis (MS), and analyzed responses by fast Fourier transform. Amplitude- and phase-spatial frequency functions were obtained and referred to as amplitude and phase "visuograms." We observed two types of abnormalities in the phase visuograms of MS patients: (1) abnormal responses at all spatial frequencies tested (37%), and (2) abnormal responses only at selective spatial frequencies (52%). Some patients had phase lag limited to low, middle, or high spatial freyuencies. Steady-state and transient VEPs to 2 and 4 cpd showed a similar percent of abnormalities. The use of o than one spatial frequency stimulus increased the diagnostic yield by 17% Our data confirm that MS may selectively affect specific neuronal channels within the visual pathways. Address correspondence and reprint requests to Dr. Gastone G. Celesia, Department of Neurology, Loyola University, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153. Supported in part by the Veterans Administration and NIH grant EY09183. Received August 23, 1991. Accepted for publication in final form October 9, 1991.
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