Faculty Bibliography

OBJECTIVE:To determine if native English speakers (NES) perform differently compared to non-native English speakers (NNES) on a sideline-focused rapid number naming task. A secondary aim was to characterize objective differences in eye movement behaviour between cohorts. BACKGROUND:The King-Devick (KD) test is a rapid number-naming task in which numbers are read from left-to-right. This performance measure adds vision-based assessment to sideline concussion testing. Reading strategies differ by language. Concussion may also impact language and attention. Both factors may affect test performance. METHODS:Twenty-seven healthy  NNES and healthy NES performed a computerized KD test under high-resolution video-oculography.  NNES also performed a Bilingual Dominance Scale (BDS) questionnaire to weight linguistic preferences (i.e., reliance on non-English language(s)). RESULTS:Inter-saccadic intervals were significantly longer in  NNES (346.3 ± 78.3 ms vs. 286.1 ± 49.7 ms, p = 0.001), as were KD test times (54.4 ± 15.1 s vs. 43.8 ± 8.6 s, p = 0.002). Higher BDS scores, reflecting higher native language dominance, were associated with longer inter-saccadic intervals in  NNES. CONCLUSION/CONCLUSIONS:These findings have direct implications for the assessment of athlete performance on vision-based and other verbal sideline concussion tests; these results are particularly important given the international scope of sport. Pre-season baseline scores are essential to evaluation in the event of concussion, and performance of sideline tests in the athlete's native language should be considered to optimize both baseline and post-injury test accuracy.

OBJECTIVE:The Mobile Universal Lexicon Evaluation System (MULES) is a test of rapid picture naming that is under investigation for concussion. MULES captures an extensive visual network, including pathways for eye movements, color perception, memory and object recognition. The purpose of this study was to introduce the MULES to visual assessment of patients with MS, and to examine associations with other tests of afferent and efferent visual function. METHODS:We administered the MULES in addition to binocular measures of low-contrast letter acuity (LCLA), high-contrast visual acuity (VA) and the King-Devick (K-D) test of rapid number naming in an MS cohort and in a group of disease-free controls. RESULTS:Among 24 patients with MS (median age 36 years, range 20-72, 64% female) and 22 disease-free controls (median age 34 years, range 19-59, 57% female), MULES test times were greater (worse) among the patients (60.0 vs. 40.0 s). Accounting for age, MS vs. control status was a predictor of MULES test times (P = .01, logistic regression). Faster testing times were noted among patients with MS who had greater (better) performance on binocular LCLA at 2.5% contrast (P < .001, linear regression, accounting for age), binocular high-contrast VA (P < .001), and K-D testing (P < .001). Both groups demonstrated approximately 10-s improvements in MULES test times between trials 1 and 2 (P < .0001, paired t-tests). CONCLUSION/CONCLUSIONS:The MULES test, a complex task of rapid picture naming involves an extensive visual network that captures eye movements, color perception and the characterization of objects. Color recognition, a key component of this novel assessment, is early in object processing and requires area V4 and the inferior temporal projections. MULES scores reflect performance of LCLA, a widely-used measure of visual function in MS clinical trials. These results provide evidence that the MULES test can add efficient visual screening to the assessment of patients with MS.

Research into sensory substitution systems has expanded, as alternative senses are utilized in real-time to afford object recognition or spatial understanding. Tactile stimulation has long shown promise as a communicatory strategy when applied unobtrusively to the redundant surface areas of the skin. Here, a novel belt, integrating a matrix of macro fiber composites, is purposed to deliver tactile stimuli to the abdomen. The design and development of the belt is presented and a systematic experimental study is conducted to analyze the impact of frequency and duty cycle. The belt is a beta precursor to a soft haptic feedback device that will enable situational awareness and obstacle avoidance through the localization of tactile stimulation relative to a body-centric frame of reference in a local environment.

: BACKGROUND:: The visual pathways are increasingly recognized as an ideal model to study neurodegeneration in multiple sclerosis (MS). Low-contrast letter acuity (LCLA) and optical coherence tomography (OCT) are validated measures of function and structure in MS. In fact, LCLA was the topic of a recent review by the Multiple Sclerosis Outcome Assessments Consortium (MSOAC) to qualify this visual measure as a primary or secondary clinical trial endpoint with the Food and Drug Administration (FDA) and other regulatory agencies. This review focuses on the use of LCLA and OCT measures as outcomes in clinical trials to date of MS disease-modifying therapies.

OBJECTIVE:Measures of rapid automatized naming (RAN) have been used for over 50 years to capture vision-based aspects of cognition. The Mobile Universal Lexicon Evaluation System (MULES) is a test of rapid picture naming under investigation for detection of concussion and other neurological disorders. MULES was designed as a series of 54 grouped color photographs (fruits, random objects, animals) that integrates saccades, color perception and contextual object identification. Recent changes to the MULES test have been made to improve ease of use on the athletic sidelines. Originally an 11 × 17-inch single-sided paper, the test has been reduced to a laminated 8.5 × 11-inch double-sided version. We identified performance changes associated with transition to the new, MULES, now sized for the sidelines, and examined MULES on the sideline for sports-related concussion. METHODS:We administered the new laminated MULES to a group of adult office volunteers as well as youth and collegiate athletes during pre-season baseline testing. Athletes with concussion underwent sideline testing after injury. Time scores for the new laminated MULES were compared to those for the larger version (big MULES). RESULTS:Among 501 athletes and office volunteers (age 16 ± 7 years, range 6-59, 29% female), average test times at baseline were 44.4 ± 14.4 s for the new laminated MULES (n = 196) and 46.5 ± 16.3 s for big MULES (n = 248). Both versions were completed by 57 participants, with excellent agreement (p < 0.001, linear regression, accounting for age). Age was a predictor of test times for both MULES versions, with longer times noted for younger participants (p < 0.001). Among 6 athletes with concussion thus far during the fall sports season (median age 15 years, range 11-21) all showed worsening of MULES scores from pre-season baseline (median 4.0 s, range 2.1-16.4). CONCLUSION/CONCLUSIONS:The MULES test has been converted to an 11 × 8.5-inch laminated version, with excellent agreement between versions across age groups. Feasibly administered at pre-season and in an office setting, the MULES test shows preliminary evidence of capacity to identify athletes with sports-related concussion.

OBJECTIVE:To evaluate the performance of the EyeTribe compared to the EyeLink for eye movement recordings during a rapid number naming test in healthy control participants. BACKGROUND:With the increasing accessibility of portable, economical, video-based eye trackers such as the EyeTribe, there is growing interest in these devices for eye movement recordings, particularly in the domain of sports-related concussion. However, prior to implementation there is a primary need to establish the validity of these devices. One current limitation of portable eye trackers is their sampling rate (30-60 samples per second, or Hz), which is typically well below the benchmarks achieved by their research-grade counterparts (e.g., the EyeLink, which samples at 500-2000 Hz). METHODS:We compared video-oculographic measurements made using the EyeTribe with those of the EyeLink during a digitized rapid number naming task (the King-Devick test) in a convenience sample of 30 controls. RESULTS:EyeTribe had loss of signal during recording, and failed to reproduce the typical shape of saccadic main sequence relationships. In addition, EyeTribe data yielded significantly fewer detectable saccades and displayed greater variance of inter-saccadic intervals than the EyeLink system. CONCLUSION/CONCLUSIONS:Caution is advised prior to implementation of low-resolution eye trackers for objective saccade assessment and sideline concussion screening.

BACKGROUND: The King-Devick (K-D) test of rapid number naming is a reliable visual performance measure that is a sensitive sideline indicator of concussion when time scores worsen (lengthen) from preseason baseline. Within cohorts of youth athletes <18 years old, baseline K-D times become faster with increasing age. We determined the relation of rapid number-naming time scores on the K-D test to electronic measurements of saccade performance during preseason baseline assessments in a collegiate ice hockey team cohort. Within this group of young adult athletes, we also sought to examine the potential role for player age in determining baseline scores. METHODS: Athletes from a collegiate ice hockey team received preseason baseline testing as part of an ongoing study of rapid rink-side performance measures for concussion. These included the K-D test (spiral-bound cards and tablet computer versions). Participants also performed a laboratory-based version of the K-D test with simultaneous infrared-based video-oculographic recordings using an EyeLink 1000+. This allowed measurement of the temporal and spatial characteristics of eye movements, including saccadic velocity, duration, and intersaccadic interval (ISI). RESULTS: Among 13 male athletes, aged 18-23 years (mean 20.5 +/- 1.6 years), prolongation of the ISI (a combined measure of saccade latency and fixation duration) was the measure most associated with slower baseline time scores for the EyeLink-paired K-D (mean 38.2 +/- 6.2 seconds, r = 0.88 [95% CI 0.63-0.96], P = 0.0001), the K-D spiral-bound cards (36.6 +/- 5.9 seconds, r = 0.60 [95% CI 0.08-0.87], P = 0.03), and K-D computerized tablet version (39.1 +/- 5.4 seconds, r = 0.79 [95% CI 0.42-0.93], P = 0.001). In this cohort, older age was a predictor of longer (worse) K-D baseline time performance (age vs EyeLink-paired K-D: r = 0.70 [95% CI 0.24-0.90], P = 0.008; age vs K-D spiral-bound cards: r = 0.57 [95% CI 0.03-0.85], P = 0.04; age vs K-D tablet version: r = 0.59 [95% CI 0.06-0.86], P = 0.03) as well as prolonged ISI (r = 0.62 [95% CI 0.11-0.87], P = 0.02). Slower baseline K-D times were not associated with greater numbers of reported prior concussions. CONCLUSIONS: Rapid number-naming performance using the K-D at preseason baseline in this small cohort of collegiate ice hockey players is best correlated with ISI among eye movement-recording measures. Baseline K-D scores notably worsened with increasing age, but not with numbers of prior concussions in this small cohort. While these findings require further investigation by larger studies of contact and noncontact sports athletes, they suggest that duration of contact sports exposure may influence preseason test performance.

This article describes pilot testing of an adaptive mobility device-hybrid (AMD-H) combining properties of two primary mobility tools for people who are blind: the long cane and adaptive mobility devices (AMDs). The long cane is the primary mobility tool used by people who are blind and visually impaired for independent and safe mobility and AMDs are adaptive devices that are often lightweight frames approximately body width in lateral dimension that are simply pushed forward to clear the space in front of a person. The prototype cane built for this study had a wing apparatus that could be folded around the shaft of a cane but when unfolded, deployed two wheeled wings 25 cm (9.8 in) to each side of the canetip. This project explored drop-off and obstacle detection for 6 adults with visual impairment using the deployed AMD-H and a standard long cane. The AMD-H improved obstacle detection overall, and was most effective for the smallest obstacles (2 and 6 inch diameter). The AMD-H cut the average drop off threshold from 1.79 inches (4.55 cm) to .96 inches (2.44 cm). All participants showed a decrease in drop off detection threshold and an increase in detection rate (13.9% overall). For drop offs of 1 in (2.54 cm) and 3 in (7.62 cm), all participants showed large improvements with the AMD-H, ranging from 8.4 to 50%. The larger drop offs of 5 in (12.7 cm) and 7 in (17.8 cm) were well detected by both types of canes.