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An Electroretinal and Visual Evoked Potential Study in Friedreich’s Ataxia

Published online by Cambridge University Press:  18 September 2015

T. H. Kirkham*
Affiliation:
Departments of Neurology, Neurosurgery and Ophthalmology, McGill University, and the Department of Neuro-Ophthalmology, Montreal Neurological Hospital
S. G. Coupland
Affiliation:
Departments of Neurology, Neurosurgery and Ophthalmology, McGill University, and the Department of Neuro-Ophthalmology, Montreal Neurological Hospital
*
Department of Neuro-Ophthalmology, Montreal Neurological Hospital, 3801 University, Montreal, Quebec, Canada H3A 2B4
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Summary:

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We made an electroretinographic (ERG) and visual evoked potential (VEP) study of 12 patients with Friedreich’s ataxia whose diagnosis was established using the Quebec diagnostic criteria. ERGs and VEPs were elicited to the same stimulating conditions. Flash evoked luminance changes and pattern-specific evoked potentials to check and diamond stimuli were used. Statistical analysis of the data was made using independent sample t-tests. Significant VEP delays were present under all test conditions. The presence of significant interocular and interhemispheric delays as well as evidence of abnormal temporal dispersion of the VEP response suggest there to be both diffuse anterior visual system disease and retrochiasmal involvement in Friedreich’s ataxia. The implicit times of the ERG b-waves were statistically within normal limits but the waveforms were of low amplitude and deformed and there were significant interocular implicit time differences. These ERG results suggest there are retinal conduction abnormalities in Friedreich’s ataxia which possibly play a role in the genesis of the abnormal VEPs.

Type
Research Article
Copyright
Copyright © Canadian Neurological Sciences Federation 1981