title: What is the lowest threshold to make a diagnosis of concussion?
abstract: OBJECTIVE
  The purpose of this review is to examine the evidence for determining the lowest threshold for diagnosing a sport-related concussion.
  
  
  METHODS
  MEDLINE, CINAHL, EMBASE, Mosby's Index, PsycEXTRA, PsycINFO and Scopus. Key words included sports concussion, concussion assessment, diagnosis, concussion symptoms, onfield assessment and sports-related traumatic brain injury.
  
  
  RESULTS
  The majority of concussions in sport occur without loss of consciousness or frank neurological signs. Some of the hallmark signs of acute concussion include mental confusion, memory and balance disturbance. Over the course of the first 24 h, the most common symptoms include headache, nausea, dizziness and balance problems, blurred vision or other visual disturbance, confusion, memory loss and 'fatigue'. Symptoms such as tiredness, irritability, nervousness or anxiety, sleep disturbance and sensitivity to light or noise may be noticed in the days after injury. The pathophysiology of sports concussion remains poorly understood. There appears to be a period of vulnerability following concussion in which an overlapping injury might cause magnified pathophysiology.
  
  
  CONCLUSIONS
  Sport-related concussions can be difficult to diagnose. Concussion produces an evolving constellation of somatic, cognitive and neurobehavioral symptoms that are typically most severe during the earliest acute postinjury period (ie, within the first 24-48 h) and diminish over a matter of several days to weeks in the majority of athletes. Athletes suspected of concussion should be removed from play and evaluated thoroughly.
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia. paulmccr@bigpond.net.au
authors.forename: Paul
authors.initials: P
authors.lastname: McCrory
authors.forename: Willem H
authors.initials: WH
authors.lastname: Meeuwisse
authors.forename: Ruben J
authors.initials: RJ
authors.lastname: Echemendia
authors.forename: Grant L
authors.initials: GL
authors.lastname: Iverson
authors.forename: Jirí
authors.initials: J
authors.lastname: Dvorák
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Kutcher
mesh_terms: D000208:Acute Disease; D001265:Athletic Injuries / Q000175:diagnosis* / Q000209:etiology; D001924:Brain Concussion / Q000175:diagnosis* / Q000209:etiology; D001928:Brain Diseases, Metabolic / Q000175:diagnosis / Q000209:etiology; D032921:Consensus; D003937:Diagnosis, Differential; D015600:Glasgow Coma Scale; D006801:Humans; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology; D009422:Nervous System Diseases / Q000175:diagnosis / Q000209:etiology; D057566:Self Report; D009626:Terminology as Topic