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M McKerral, J Lachapelle, J Kremlacek, A Ptito, P Lachapelle; Visual and Cognitive Information Processing After Traumatic Brain Injury: VEP and ERP Studies . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1803.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Individuals having sustained a traumatic brain injury (TBI) often exhibit difficulties related to visual processing as well as more global information processing that can be difficult to objectify with the methods commonly used in the clinical neuro-trauma setting. The present study aimed at evaluating, with the use of objective functional methods, these aspects in relation to TBI severity and recuperation variables. Methods: VEPs and ERPs were obtained from Fz, Cz, Pz, Oz, Ol and Or (5 cm to left and right of Oz) in a cohort of TBI patients of varying severity and at different stages of the recuperation process, as well as in a cohort of normal control subjects. VEPs were recorded to a reversing checkerboard (40 min of arc checks, 96% contrast) and to a randomly moving pattern (40 min of arc checks, 80 min of arc period, 10% contrast). ERPs were obtained by having the subject signal rare events (upward moving pattern) that appeared randomly among frequent events (downward moving pattern). Motor reaction times (RT) were obtained simultaneously to the VEPs and ERPs. Results: Significantly (p<0.05) abnormal VEP responses (amplitude or timing) were obtained from TBI subjects which indicate either pattern-processing, motion-analysis or combined deficits, in the presence or not of a signiticantly (p<0.05) reduced P300 amplitude. Also, the RT was significantly (p<0.05) longer in TBI subjects compared to normal controls, but not always concomitantly with VEP timing delays. VEP and ERP abnormalities generally correlate well with TBI severity. Conclusion: VEPs and ERPs evoked to specific and well-defined stimuli can objectify the presence of post-TBI deficits at primary as well as at more complex levels of information processing. This investigative approach can also help identifying sub-clinical deficits and thus contribute to improve the clinical follow-up of these patients.
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