title: Differential rate of recovery in athletes after first and second concussion episodes.
abstract: OBJECTIVE
  Clinical observations suggest that a history of previous concussions may cause a slower recovery of neurological function after recurrent concussion episodes. However, direct examination of this notion has not been provided. This report investigates the differential rate of restoring the visual-kinesthetic integration in collegiate athletes experiencing single versus recurrent concussion episodes.
  
  
  METHODS
  One hundred sixty collegiate athletes were tested preseason using multimodal research methodology. Of these, 38 experienced mild traumatic brain injury (MTBI) and were tested on Days 10, 15, and 30 after injury. Nine of these MTBI patients experienced a second MTBI within 1 year after the first brain injury and were retested. The postconcussion symptoms checklist, neuropsychological evaluations, and postural responses to visual field motion were recorded using a virtual reality environment.
  
  
  RESULTS
  All patients were asymptomatic at Day 10 of testing and were cleared for sport participation based on clinical symptoms resolution. Balance deficits, as evident by incoherence with visual field motion postural responses, were present at least 30 days after injury (P < 0.001). Most importantly, the rate of balance symptoms restoration was significantly reduced after a recurrent, second concussion (P < 0.001) compared with those after the first concussion.
  
  
  CONCLUSIONS
  The findings of this study confirm our previous research indicating the presence of long-term residual visual-motor disintegration in concussed individuals with normal neuropsychological measures. Most importantly, athletes with a history of previous concussion demonstrate significantly slower rates of recovery of neurological functions after the second episode of MTBI.
authors.affiliation: Department of Kinesiology, Pennsylvania State University, University Park, Pennsylvania 16802, USA. sms18@psu.edu
authors.forename: Semyon
authors.initials: S
authors.lastname: Slobounov
authors.forename: Elena
authors.initials: E
authors.lastname: Slobounov
authors.forename: Wayne
authors.initials: W
authors.lastname: Sebastianelli
authors.forename: Cheng
authors.initials: C
authors.lastname: Cao
authors.forename: Karl
authors.initials: K
authors.lastname: Newell
mesh_terms: D000293:Adolescent; D000328:Adult; D001265:Athletic Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D001924:Brain Concussion / Q000175:diagnosis* / Q000503:physiopathology*; D003943:Diagnostic Techniques, Neurological / Q000295:instrumentation; D005260:Female; D006801:Humans; D007699:Kinesthesis; D008137:Longitudinal Studies; D008297:Male; D008954:Models, Biological; D004856:Postural Balance; D011187:Posture; D011597:Psychomotor Performance; D020127:Recovery of Function; D012008:Recurrence; D014584:User-Computer Interface; D014794:Visual Fields