title: Rapid number naming in chronic concussion: eye movements in the King-Devick test.
abstract: The King-Devick (KD) test, which is based on rapid number naming speed, is a performance measure that adds vision and eye movement assessments to sideline concussion testing. We performed a laboratory-based study to characterize ocular motor behavior during the KD test in a patient cohort with chronic concussion to identify features associated with prolonged KD reading times.
  
  
  
  Twenty-five patients with a concussion history (mean age: 31) were compared to control participants with no concussion history (n= 42, mean age: 32). Participants performed a computerized KD test under infrared-based video-oculography.
  
  
  
  Average intersaccadic intervals for task-specific saccades were significantly longer among concussed patients compared to controls (324.4 ± 85.6 msec vs. 286.1 ± 49.7 msec,P= 0.027). Digitized KD reading times were prolonged in concussed participants versus controls (53.43 ± 14.04 sec vs. 43.80 ± 8.55 sec,P= 0.004) and were highly correlated with intersaccadic intervals. Concussion was also associated with a greater number of saccades during number reading and larger average deviations of saccade endpoint distances from the centers of the to-be-read numbers (1.22 ± 0.29° vs. 0.98 ± 0.27°,P= 0.002). There were no differences in saccade peak velocity, duration, or amplitude.
  
  
  
  Prolonged intersaccadic intervals, greater numbers of saccades, and larger deviations of saccade endpoints underlie prolonged KD reading times in chronic concussion. The KD test relies upon a diffuse neurocognitive network that mediates the fine control of efferent visual function. One sequela of chronic concussion may be disruption of this system, which may produce deficits in spatial target selection and planning of eye movements.
authors.affiliation: Department of Physical Medicine & Rehabilitation NYU School of Medicine New York New York; Department of Neurology NYU School of Medicine New York New York.
authors.forename: John-Ross
authors.initials: JR
authors.lastname: Rizzo
authors.affiliation: Department of Physical Medicine & Rehabilitation NYU School of Medicine New York New York; Department of Neurology NYU School of Medicine New York New York.
authors.forename: Todd E
authors.initials: TE
authors.lastname: Hudson
authors.affiliation: Department of Electrical & Computer Engineering NYU Tandon School of Engineering New York New York.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Dai
authors.affiliation: Department of Physical Medicine & Rehabilitation NYU School of Medicine New York New York.
authors.forename: Joel
authors.initials: J
authors.lastname: Birkemeier
authors.affiliation: Department of Physical Medicine & Rehabilitation NYU School of Medicine New York New York.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Pasculli
authors.affiliation: Department of Electrical & Computer Engineering NYU Tandon School of Engineering New York New York.
authors.forename: Ivan
authors.initials: I
authors.lastname: Selesnick
authors.affiliation: Department of Neurology NYU School of Medicine New York New York; Department of Population Health NYU School of Medicine New York New York; Department of Ophthalmology NYU School of Medicine New York New York.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Balcer
authors.affiliation: Department of Neurology NYU School of Medicine New York New York; Department of Ophthalmology NYU School of Medicine New York New York.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Galetta
authors.affiliation: Department of Neurology NYU School of Medicine New York New York.
authors.forename: Janet C
authors.initials: JC
authors.lastname: Rucker