Objective: To assess the relation of quantitative eye movements with cognitive dysfunction in concussion.
Background: Inter-saccadic interval (ISI) prolongation during rapid number naming on King-Devick (K-D) testing has been shown to underlie longer test times in patients with a history of concussion. The ISI is a measure of time between saccades, representing saccadic latency and fixation duration. Prolongation may result from increased saccade latency either as a result of, or in concert with, impaired attention and/or cognition. We sought to determine the relation of ISI prolongation and neuropsychological testing in a range of cognitive domains in concussion.
Methods: Analysis of sixteen patients with a concussion history (mean age 41.7 +/-13.6 years, range 24- 65) who performed K-D with eye movement recordings (EyeLink 1000+) and underwent neuropsychological testing. Primary neuropsychological measures included tests assessing effort, pre-morbid intellectual functioning, processing speed, attention and working memory, executive function, and mood as part of a concussion battery. Spearman rank-correlations were performed to examine the relation of ISI and neuropsychological measures.
Result: Among 16 participants, aged 41.7 +/- 13.6 years, mean K-D test time was 72.6s +/-20.7; this is longer than the expected control value of 41.5s (prior studies). Mean ISI was 379.1msec +/-199.1. Greater ISI prolongation was associated with lower scores on measures of processing speed and attention/working memory: Trails Making Test Part A (rs=-0.64, P=0.009); Stroop Color Word (rs=-0.69, P=0.003); Digit Span Backward (rs =-0.59 P =0.02) and Digit Span Total (rs =-0.65 P =0.006).
Conclusion: Results demonstrate associations between ISI prolongation and worse neuropsychological scores among patients with a history of concussion. Such deficits may reflect involvement of the dorsolateral prefrontal cortex (DLPFC) and subcortical structures in concussion, as these facilitate saccades, processing speed, and working memory. Ongoing studies will further refine cognitive function domains most associated with eye movement physiology in concussion.
- K-D test and ISI times were prolonged in patients with a positive concussion history and were associated with lower cognitive scores
- These results may reflect associations between cognitive function domains and eye movement physiology in concussion.