What is a concussion?

Concussion is a type of brain injury defined as a "complex pathophysiological process affecting the brain, induced by biomechanical forces." [1-3]


The nature of concussive head injury include:
  • A concussion represents a disturbance to brain function caused by a blow or a "violent shaking" of the head, neck, or body. A concussion can result even if a person is not hit directly in the head, as an "impulsive" force may be transmitted to the brain from a blow elsewhere on the body.
  • Concussions typically result in the rapid onset of short lived impairments of brain function that most often resolves spontaneously. Concussions represent a disruption of brain function rather than a structural injury, and no abnormalities are seen during standard brain imaging, such as MRI and CT scans.
  • Loss of consciousness does not need to occur for a person to be concussed.


Is a concussion a brain injury?
  • Trauma or forceful impact to the body or head can cause damage to our brain tissue.
  • At the cellular level, impact forces cause injury to neuron cell membranes and disrupt the normal metabolic function of these brain cells.
  • Any change or temporary alteration the brain's neurometabolic function from an impact force  is referred to as a mild traumatic brain injury.


What happens when our brain's chemicals are disrupted?
  • Our brain controls all of our "thinking" and "doing" by conducting millions and millions of chemical reactions per second.
  • A disruption in any of these chemical reactions in our brain can result in temporary change in our ability to think and function normally.
  • A person may have difficulty with memory, processing information quickly, and reaction time. This may result in diminished academic performance and athletic performance and social & emotional behavior changes.

How is a concussion diagnosed?

Only a Licensed Health Care Provider trained in concussion management should diagnose a concussion.

  • The diagnosis is based off a comprehensive clinical evaluation and supported by specialized concussion assessment tools.
  • Concussion assessment tools alone do not diagnosis a concussion; they are used in conjunction with a medical evaluation to identify concussions and to assist the medical professional in devising a specific treatment plan for an athlete's injury.
  • The severity of a concussion is no longer diagnosed on a grading scale (i.e. mild, moderate, or severe concussion). Concussions are graded retrospectively once a person has fully recovered, and they are categorized based on the recovery time.

Is there any imaging or specialized test that can detect a concussion?

The injuries sustained by brain cells during a concussion are chemical, not "structural" and are not visible. Therefore, concussions cannot be detected by any standard imaging such as X-Ray, CT scan or MRI. These scans will be normal in concussion.  X-Ray, CT or MRI is helpful, when appropriate, to rule out structural damage like brain bleeds or skull fractures.

A Licensed Health Care Provider can determine if an individual has a sustained a concussion.

  • Licensed Health Care Providers are Physicians, Certified Athletic Trainers, Neuropsychologists, Physician Assistants, or Advanced Practice Registered Nurses.
  • Everyone may exhibit different signs & symptoms with each unique concussion injury, and the treatment and recovery will be different and tailord specifically for each person.
  • A licensed Health Care provider shall provide medical clearance before a person may engage in any type of physical activity, practice, game, or competition after being diagnosed with a concussion.
  • This is mandated by Hawaii State Law ACT 262

Why is the treatment and recovery different?
  • Each concussion may cause different degrees of injury to different parts of the brain which control different body functions.  Every concussion is unique.
  • The treatment depends on the specific signs & symptoms a person is exhibiting and experiencing.
  • Recovery from a concussion is multifactorial.

[1] Broglio, S.P., et al., National Athletic Trainers' Association position statement: management of sport concussion. J Athl Train, 2014. 49(2): p. 245-65.
[2] Cantu, R.C., Consensus statement on concussion in sport--the 3rd International Conference on Concussion, Zurich, November 2008. Neurosurgery, 2009. 64(5): p. 786-7.
[3] Harmon, K.G., et al., American Medical Society for Sports Medicine position statement: concussion in sport. Br J Sports Med, 2013. 47(1): p. 15-26.