Residency Training: The King-Devick test and sleep deprivation Study in pre- and post-call neurology residents

Departments of Neurology, University of Pennsylvania School of Medicine, Philadelphia, USA.
Neurology (Impact Factor: 8.29). 04/2012; 78(17):e103-6. DOI: 10.1212/WNL.0b013e318251833d
Source: PubMed


The current study investigates the effect of sleep deprivation on the speed and accuracy of eye movements as measured by the King-Devick (K-D) test, a <1-minute test that involves rapid number naming.
In this cohort study, neurology residents and staff from the University of Pennsylvania Health System underwent baseline followed by postcall K-D testing (n = 25); those not taking call (n = 10) also completed baseline and follow-up K-D testing. Differences in the times and errors between baseline and follow-up K-D scores were compared between the 2 groups.
Residents taking call had less improvement from baseline K-D times when compared to participants not taking call (p < 0.0001, Wilcoxon rank sum test). For both groups, the change in K-D time from baseline was correlated to amount of sleep obtained (r(s) = -0.50, p = 0.002) and subjective evaluation of level of alertness (r(s) = 0.33, p = 0.05) but had no correlation to time since last caffeine consumption (r(s) = -0.13, p = 0.52). For those residents on their actual call night, the duration of sleep obtained did not correlate with change in K-D scores from baseline (r(s) = 0.13, p = 0.54).
The K-D test is sensitive to the effects of sleep deprivation on cognitive functioning, including rapid eye movements, concentration, and language function. As with other measures of sleep deprivation, K-D performance demonstrated significant interindividual variability in vulnerability to sleep deprivation. Severe fatigue appears to reduce the degree of improvement typically observed in K-D testing.

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    • "Originally developed as a reading tool to assess the relationship between poor oculomotor functions and learning disabilities, the King–Devick (K–D) test utilises a series of charts of numbers that progressively become more difficult to read in a flowing manner [13]. The K–D test requires eye movements, language function and attention in order to perform tasks reflective of suboptimal brain function in hypoxia [14], extreme sleep deprivation [15], Parkinson's [16] and concussion [17] [18] [19] [20] [21] [22] [23] [24]. Several sports, such as boxing and mixed martial arts [18] [23], professional ice hockey [20], representative rugby league [22] and domestic rugby union, have utilised the K–D and identified unwitnessed concussive events. "
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    ABSTRACT: Aim: To use the King–Devick (K–D) test in senior amateur rugby union and rugby league players over a domestic competition season to see if it could identify witnessed and unwitnessed episodes of concussion that occurred from participation in competition matches over three years. Methods: A prospective observational cohort study was conducted on a club level senior amateur rugby union team (n = 36 players in 2012 and 35 players in 2013) and a rugby league team (n = 33 players in 2014) during competition seasons in New Zealand. All 104 players completed two trials 10 min apart of the K–D at the beginning of their competition season. Concussions (witnessed or unwitnessed) were only recorded if they were formally diagnosed by a health practitioner. Results: A total of 52 (8 witnessed; 44 unwitnessed) concussive events were identified over the duration of the study resulting in a concussion injury incidence of 44 (95% CI: 32 to 56) per 1000 match participation hours. There was a six-fold difference between witnessed and unwitnessed concussions recorded. There were observable learning effects observed between the first and the second K–D test baseline testing (50 vs. 45 s; z = −8.81; p b 0.001). For every 1 point reduction in each of the post-injury SAC components there was a corresponding increase (worsening) of K–D test times post-match for changes in orientation (2.9 s), immediate memory (1.8 s) concentration (2.8 s), delayed recall (2.0 s) and SAC total score (1.7 s). Discussion: The rate of undetected concussion was higher than detected concussions by using the K–D test routinely following matches. Worsening of the K–D test post-match was associated with reduction in components of the SAC. The appeal of the K–D test is in the rapid, easy manner of its administration and the reliable, objective results it provides to the administrator. The K–D test helped identify cognitive impairment in players without clinically observable symptoms.
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