Purchase this article with an account.
J. Lachapelle, M. McKerral; Electrophysiological Study of Visual Information Processing After Mild Traumatic Brain Injury . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3603.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Individuals having sustained a traumatic brain injury (TBI) often exhibit difficulties related to visual function and global information processing. In mild TBI (MTBI), those deficits and their physiological correlates are subtle and while they can have negative impacts on their life habits, they can be difficult to objectify with the methods commonly used in the clinical neurotrauma setting (CT scan, MRI, etc.) Previous studies have demonstrated the usefulness of electrophysiological assessment in objectifying post–TBI functional problems. The present study thus aimed at identifying, following MTBI, the relationship between the extent of information processing deficits at different stages of visual analysis (as evidenced with evoked potentials: EPs) and the clinical information. Methods: Visual evoked potentials (VEPs) and cognitive event–related potentials (ERPs) were obtained from 19 patients with MTBI and in 23 control subjects. Low–level, motion and texture VEPs were recorded from Oz, Ol, Or to a reversing checkerboard (0.2º, 0.8º checks, 98% contrast, 2 Hz temp. freq.), an expanding target (0.7º components, 20% contrast, 1 Hz temp. freq.) and texture–oriented line segments (7.3º width, 90% contrast, 1 Hz temp. freq.) respectively. ERPs were recorded from Pz, Cz, Fz. Subjects signaled rare events (1.5º checks, 20% contrast) appearing randomly among frequent events (0.5º checks, 20% contrast). Clinical information (neuroradiological, neuropsychological) as well as symptoms and life habits were analyzed and correlated with the electrophysiological data. Results: Mean results did not show consistent VEP patterns allowing to clearly differentiate MTBI from control subjects. However, individual results showed ERPs as being the most affected electrophysiological measure. This finding is consistent with the clinical symptomatology where deficits related to cognitive functions were most affected. Individual results showed that electrophysiological evaluation permitted to objectify sub–clinical deficits in the presence of visual symptomatology, which was not the case with the usual clinical methods. Conclusions: Comparison of different EPs with clinical information permits a better understanding of the relationship between TBI severity and its functional consequences. The latter can be good markers of cerebral function recovery, help to refine diagnosis and prognosis, and ensure an accurate follow–up.
This PDF is available to Subscribers Only