title: A narrative review of sports-related concussion and return-to-play testing with asymptomatic athletes.
abstract: OBJECTIVE
  The purpose of this literature review was to demonstrate, through examples in the current literature, the cumulative and long-term effects of multiple concussions, postinjury protocols, and the efficacy of current and past return-to-play guidelines.
  
  
  METHODS
  A PUBMED SEARCH WAS PERFORMED USING THE KEYWORDS AND KEY PHRASES: concussions and long-term effects, concussions and return to play, and multiple concussions. We limited the search to articles that had been published from August 2007 to August 2012 and were specific to human participants. Of the 450 total articles that the search returned, we selected studies specifically demonstrating athletes who were symptom-free, passed neuropsychological testing, returned to play, and were tested in measures of postural control, transcranial magnetic stimulation, electroencephalographic studies, and magnetic resonance imaging spectroscopy.
  
  
  RESULTS
  Selected studies show evidence that, although a previously concussed athlete may be symptom-free and returned to a neuropsychological baseline, the athlete may continue to have prolonged neurological abnormalities that could disqualify them from being ready to return to play.
  
  
  CONCLUSIONS
  It appears that some neurological deficits persist beyond the current return-to-play standards and that discrepancy exists between common practices of returning athletes to competition and new standards of published research.
authors.affiliation: Private practice, Arlington Heights, IL.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Porcher
authors.affiliation: Assistant Professor, National University of Health Sciences, Lombard, IL.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Solecki
keywords: Athletic injuries; Brain concussion; Chiropractic; Postconcussion syndrome