Concussion/Mild traumatic brain injury (mTBI) is a significant cause of morbidity and mortality, with many survivors of concussion/mTBI dealing with persisting difficulties for years post-injury.1-3 Over the years, various terms have been used synonymously with mild traumatic brain injury, such as mild head injury and concussion. It is important to note that all concussions are considered to be a mTBI however mTBI is distinguished from concussion when there is evidence of intracranial injury on conventional neuroimaging or there is persistent neurologic deficit.
Concussion/mTBI denotes the acute neurophysiological event related to blunt impact or other mechanical energy applied to the head, neck or body (with transmitting forces to the brain), such as from sudden acceleration, deceleration or rotational forces. Concussion can be sustained from a motor vehicle crash, sport or recreational injury, falls, workplace injury, assault or incident in the community.
Clinical signs of concussion immediately following the injury include any of the following:
Concussion is a traumatic brain injury at the beginning of the brain injury spectrum ranging from mild to severe brain injury. Mild TBI is among the most common neurological conditions with an estimated annual incidence of 500/100,000 in the United States.6 One Canadian study examining both hospital-treated cases as well as those presenting to a family physician calculated the incidence of mTBI in Ontario to lie between 493/100,000 and 653/100,000, depending on whether diagnosis was made by primary care physicians or a secondary reviewer.7
There has been much research in the role of structural imaging in diagnosing concussion/mTBI and persistent symptoms, however studies have yet to find a consistent pattern in structural brain changes to diagnose concussion/mTBI and further research is needed.8-10 Computed Tomography (CT) and conventional Magnetic Resonance Imaging (MRI) usually fail to detect evidence of structural brain abnormalities in mTBI. Research in Diffusion Tensor Imaging (DTI) to detect white matter changes post-concussion/mTBI has detected structural changes acutely following, but results have not been shown to be consistent across groups, the resolution does not get at the submillimeter level and is only detecting macroscopic changes, therefore these tests are unable to accurately diagnose concussion/mTBI.11-13 DTI has also been researched in people with chronic persistent symptoms14-16 however more research is needed as the association with persistent symptoms has not been established. Reviews of recent advances in the biomechanical modeling of mTBI in humans and animals conclude that mTBI leads to functional neuronal disruption, and at times structural damage.4,17-19
There are several criteria commonly used to index severity of traumatic brain injuries. One of the most commonly used is the Glasgow Coma Scale (GCS),20 which assesses a patient’s level of consciousness. GCS scores can range from 3 to 15; mTBI is defined as a GCS score of 13-15, typically measured at 30 minutes post-injury or “on admission.” Post-traumatic amnesia (PTA), measured as the time from when the trauma occurred until the patient regains continuous memory, is another criterion used to define injury severity, and the cut-off for mild injuries is usually placed at 24 hours or less. Finally, a loss of consciousness of less than 30 minutes has also served as an index of mTBI.21 However, it should be noted that mTBI can occur in the absence of any loss of consciousness. The acute symptoms that may follow mTBI are often categorized according to the following domains: 1) physical, 2) behavioural/emotional and 3) cognitive. Some of the more common representatives of each symptom category are presented in Table A.
Disparities exist in the definitions used for mTBI, and several organizations have created formal diagnostic criteria in order to try to overcome inconsistencies. Due to this fact the Expert Consensus Group (see Methodology) established a subcommittee to review the diagnostic criteria of concussion/mTBI. Experts reviewed recent definitions of concussion/mTBI as published by established mTBI consensus groups (sport, military) and from clinical practice guidelines. Depending on the population studied the literature would suggest that minimally 15% of persons with concussion may experience prolonged symptoms beyond the typical 3 month time frame.22 The consequences for these individuals may include reduced functional ability, heightened emotional distress, and delayed return to work or school.5 When symptoms persist beyond the typical recovery period of three months, the term post-concussion syndrome or disorder may be applied.
Just as there is confusion surrounding the definition of mTBI, this is also the case with the definition of post-concussion syndrome. There has been debate as to whether prolonged symptoms are best attributed to biological or psychological factors. It now appears that a variety of interacting neuropathological and psychological contributors both underlie and maintain post-concussive symptoms.24,25 One source of controversy has been the observation that the symptoms found to persist following mTBI are not specific to this condition. They may also occur in other diagnostic groups, including those with chronic pain,26-28 depression29 and post-traumatic stress disorder,30 and are observed to varying extent among healthy individuals.31-33 For the purposes of this guideline prolonged symptoms refer to: A variety of physical, cognitive, emotional and behavioural symptoms that may endure for weeks or months following a concussion.34
Overall approach to treatment:
Phase of recovery should be considered in regards to treatment approaches:
Another area of controversy is the potential influence of related litigation and financial compensation on the presentation and outcome for persons who have sustained mTBI. While there is consistent evidence of an association between seeking/ receiving financial compensation (i.e., via disability benefits or litigation) and the persistence of post-concussive symptoms, this relationship is complex and the mechanisms through which litigation/financial compensation issues affect rate of recovery are not well studied.35 Further, it must not be assumed that the initiation of a compensation claim arises solely from the pursuit of secondary gain.36,37 The intentional exaggeration or manufacturing of symptoms (i.e., malingering) is relatively rare, whereas there are many potential factors which can contribute to symptom expression and accentuation, including levels of emotional distress, fatigue, and pain, as well as pre- and post-injury coping/adaptation.38,39 The focus within the healthcare provider-patient interaction must be upon the development of a collaborative therapeutic alliance, as it is from this vantage point that an accurate understanding of the patient’s beliefs and experience of symptoms can arise and, in turn, form the basis for an appropriate treatment plan.