Electrophysiological correlates of visual impairments after traumatic brain injury

Abstract

Our aims were to investigate: (i) the VEP correlates of functional visual impairments following traumatic brain injury (TBI), in particular of the reduced spatial form perception; and (ii) the VEP correlates of visual sustained arousal in TBI patients. We used two approaches: (i) the analysis of latency and amplitude of the peaks; and (ii) the study of the correlations among the latencies of the peaks as a label of temporal synchronization. Thirty-five severe TBI outcome inpatients and 35 matching controls were studied. Pattern-reversal VEPs were recorded at Oz-Fz and Cz-A1, first without counting, then with counting of the reversals. Seven peaks of the waveform at Oz and eight peaks at Cz were measured. We found several differences in amplitude and latency between patients and controls, and between nocount/count. The temporal binding of the peaks within each channel and between the two channels was calculated by correlation matrices, and tested by factor analysis. Results indicated that the synchronization of the peaks within each channel did not differ between patients and controls. The temporal covariation between peaks occurring at Oz and Cz, however, was highly significantly altered in patients. This suggests that visual impairments in TBI patients may be due to a deranged synchronization of the activity of different brain regions.

Automating the assessment of visual dysfunction after traumatic brain injury

“…More research is needed to explore the utility of VMSS as a reliable biomarker for mTBI. VMSS and other biomarkers of mTBI have been reported to be detectable through the recording of visual evoked potentials (VEPs) [18]. Notably, wireless recording systems for evoked potentials have recently been developed [19].…”

Evaluation of traumatic brain injury: Brain potentials in diagnosis, function, and prognosis

“…(Duncan et al, 1994(Duncan et al, , 2003(Duncan et al, , 2009Johnson, 1989aJohnson, , 1989bPolich, 2007). The majority of ERP studies of TBI have used auditory tasks (Elting et al, 2005(Elting et al, , 2008Lew et al, 2007a;Naito et al, 2005;Reza et al, 2006Reza et al, , 2007Rousseff et al, 2006;Sarno et al, 2006;Segalowitz et al, 1997Segalowitz et al, , 2001Solbakk et al, 1999Solbakk et al, , 2002. Others have used visual tasks (Broglio et al, 2009;LaChapelle et al, 2008;Lew et al, 2005b;Roche et al, 2004), and a few have used tasks in both modalities (Bernstein, 2002;Doi et al, 2007;Duncan et al, 2003Duncan et al, , 2005Lew et al, 2004Lew et al, , 2007cLew et al, , 2009.…”

“…Variations in the task used to elicit ERPs may also affect the results of studies of TBI survivors (Bernstein, 2002;Doi et al, 2007;Duncan et al, 2003Duncan et al, , 2005Lew et al, 2007c;Reza et al, 2006;Sarno et al, 2006;Segalowitz et al, 2001). Task variations include presenting an oddball paradigm in which auditory stimuli vary in duration (Bernstein, 2002;Segalowitz et al, 2001), using a motor response (button press) versus keeping a silent count of target stimuli (Reza et al, 2006), or counting silently versus passive listening (Sarno et al, 2006).…”

“…Task variations include presenting an oddball paradigm in which auditory stimuli vary in duration (Bernstein, 2002;Segalowitz et al, 2001), using a motor response (button press) versus keeping a silent count of target stimuli (Reza et al, 2006), or counting silently versus passive listening (Sarno et al, 2006). Other manipulations involve varying task demands among discrimination tasks (simple, go/no-go, and choice response; Duncan et al, 2003) or using a challenging task (such as the Continuous Performance Test; Duncan et al, 2005).…”

“…When the requirements of the task exceed the available processing resources, performance declines and P300 amplitude is reduced. Sarno et al (2006) administered passive (ignore) and active (counting) oddball tasks to survivors of severe TBI and healthy controls. In comparison to controls, N2b in TBI survivors was longer in latency in both active and passive conditions.…”