title: Differential rates of recovery after acute sport-related concussion:  electrophysiologic, symptomatic, and neurocognitive indices.
abstract: OBJECTIVE
  To determine if motor evoked potentials (MEPs), postconcussion signs and symptoms, and neurocognitive functions follow a similar recovery pattern after concussion.
  
  
  METHODS
  Nine collegiate athletes with acute concussion (>24 hours after injury) participated in this retrospective time series design. Transcranial magnetic stimulation was applied over the motor cortex, and MEPs were recorded from the contralateral upper extremity. Self-reported symptoms were evaluated using the Head Injury Scale, and the Concussion Resolution Index was used to assess neurocognitive function. All measures were repeated on days 3, 5, and 10 after injury.
  
  
  RESULTS
  Composite scores on the Head Injury Scale were significantly higher on day 1 after injury (F3,51 = 15.3; P = 0.0001). Processing speed on the Concussion Resolution Index was slower on days 1, 3, and 5 compared with that on day 10 (F3,24 = 6.75; P = 0.0002). Median MEP latencies were significantly longer on day 10 compared with day 1 after concussion (t8 = -2.69; P = 0.03). Ulnar MEP amplitudes were significantly smaller on day 3 after concussion compared with day 5 (t8 = -3.48; P = 0.008).
  
  
  CONCLUSIONS
  Acutely concussed collegiate athletes demonstrate changes in MEPs, which persist for up to 10 days after injury and do not follow the same recovery pattern as symptoms and neuropsychological test performance. The apparent differential rates of recovery most likely indicate different pathophysiological processes occurring in the immediate postconcussion period.
authors.affiliation: Concussion Assessment Research Laboratory, University of Kentucky, Lexington, KY, USA. scott.livingston@uky.edu
authors.forename: Scott C
authors.initials: SC
authors.lastname: Livingston
authors.forename: Howard P
authors.initials: HP
authors.lastname: Goodkin
authors.forename: Jay N
authors.initials: JN
authors.lastname: Hertel
authors.forename: Ethan N
authors.initials: EN
authors.lastname: Saliba
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Barth
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Ingersoll
mesh_terms: D001924:Brain Concussion / Q000503:physiopathology* / Q000523:psychology*; D003071:Cognition / Q000502:physiology*; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology; D009483:Neuropsychological Tests; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D055815:Young Adult