Abstract
USN is a common occurrence in right hemisphere stroke survivors. However, no gold standard measure of USN exists. We investigated whether eye tracking is a sensitive measure of left USN in eight people with acute right hemisphere stroke. Eye tracking was found to be more sensitive than paper-and-pencil–based tests and comparable to functional assessments of USN. We suggest that eye tracking may be a quick and effective way to screen for left USN.
Primary Author and Speaker: Kelsey Watters
Contributing Authors: Gabrielle Escalante, Leora Cherney, Sameer Ashaie
Unilateral Spatial Neglect (USN) occurs in roughly 50% of right hemisphere (RH) stroke survivors. Persons with USN have difficulty perceiving, attending, and orienting to stimuli contralateral to their brain lesion. As a result, individuals with USN are less efficient when performing activities of daily living compared to those without neglect. There is, however, no gold standard assessment for identifying USN. Some studies rely on pencil-and-paper based tests while others rely on functional assessments to identify USN. Functional assessments of neglect maybe more sensitive than pencil-and-paper based tests but place a higher cognitive demand on persons with stroke. Recent research has suggested that eye-tracking is a more sensitive measure of identifying left USN than pencil-and-paper based tests. However, the sensitivity of eye-tracking measures in comparison to functional assessments have not been established. In this preliminary study, we investigated the sensitivity of eye-tracking in identifying left USN compared to both functional and pencil-and-paper based assessments.
We recruited eight persons (Mean Age = 65.6 years, Females = 3) with an acute (Mean Time Post Onset Stroke = 22.75 days) right hemisphere stroke from the inpatient units of a rehabilitation hospital in Chicago. Participants completed the Catherine Bergago Scale via the Kessler Foundation Neglect Assessment Process (CBS-KF-NAP) for functional assessment of USN. Scores ≥ 1 indicate left USN. We used the Star Cancellation and the Line Bisection Tests of the Behavioral Inattention Test (BIT) as pencil-and-paper based assessments of neglect. Scores ≤51 indicate the presence of USN on the BIT Star Cancellation Test while ≤ 7 indicate USN on the BIT Line Bisection Test. For eye-tracking, we used pictures of a meal, sink with toiletries, and a room with furniture from the BIT. Participants were asked to look at the pictures and name as many items as they can while their gaze was tracked with Tobii TX-300 eye-tracker. All participants gaze was successfully tracked. Participants also completed the Montreal Cognitive Assessment [Mean score = 19.25 (± 4.13). For eye-tracking analysis, we computed a spatial exploration index [number of fixations in the right area of interest (e.g., right side of the room) − number of fixations in the left area of interest (e.g., left side of the room)] / [number of fixations in the right area of interest + number of fixations in the left area of interest)]. Score > 0 denotes bias towards the right area of interest while score < 0 denotes bias towards the left area of interest.
Kendall’s tau-b non-parametric correlation analyses revealed a significant correlation between spatial exploration index and BIT Star Cancellation Test (τ b = -.68, p = .033) and approaching significance between spatial exploration index and CBS-KF-NAP (τ b = .55, p = .060) and BIT Line bisection Test (τ b = -.59, p = .060). BIT Star cancellation Test and BIT Line Bisection were significantly correlation (τ b = .81, p = .022) while approaching significance between CBS via KF-NAP and BIT Line Bisection Test (τ b = -.60, p = .058). BIT Star Cancellation Test identified 1 participant with left USN while BIT Line Bisection Test identified 3 participants with left USN. CBS-KF-NAP identified 6 participants with left USN while eye-tracking identified 5 participants with left USN.
Our preliminary results confirm that eye-tracking is more sensitive than pencil-and-paper based tests of USN and maybe as comparable as CBS-KF-NAP in identifying left USN. Eye-tracking took less than 5 minutes to complete and yielded similar results to a functional test in detecting left USN. We suggest that eye-tracking may be a quick and effective way to screen for left USN after a RH stroke.
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