History and exam
Key diagnostic factors
common
direct blow to the head or deceleration of the head from an impulsive force
A typical history begins with establishing how the injury occurred and whether the impact was directly to the head or transmitted to the head by the acceleration-deceleration of the body on impact, corroborated by an observer when possible.[5]
previous brain trauma, substance use, or alcohol misuse
Previous brain traumas lower the impact threshold, making mild traumatic brain injury (TBI) more likely regardless of the force of impact.
Alcohol and drug misuse is associated with a significantly higher risk for all forms of TBI, but this is confounded by a higher overall risk for all forms of external injury.[34][35]
Other diagnostic factors
common
headache
Most commonly reported symptom.[52][53] Although often felt immediately, headache can worsen the day after the injury is sustained. 30% of patients with mild TBI continue to report headache at three months post-trauma.[54] Medication overuse, neck injuries, sleep disturbance and psychological comorbidity may all contribute to headache after mild TBI.[55]
feeling foggy/slow
dizziness/balance problems
Patients often report dizziness and imbalance. When occurring after a head injury, dizziness and balance problems are typically related to benign paroxysmal positional vertigo.[55] These symptoms may be alarming to patients if they do not settle quickly. Explaining that they are due to debris dislodged into the inner ear by the injury can help to alleviate patients’ concerns about "brain damage".[55] Vestibular migraine and depersonalization (a sense of disconnection from the body) are other causes of dizziness in this population. Central vestibular disorders can occur but are more typical after moderate or severe brain injury.[55] See Benign paroxysmal positional vertigo.
memory difficulties
Can be centered on the injury incident itself or generalized to include difficulty in day-to-day situations, and typically co-occur with other cognitive and/or physical symptoms, such as headaches. Memory lapses are common in the general population and are not specific to mild TBI.[55]
vomiting/nausea
Less typical in adults, occurring much more frequently in adolescents and children. When vomiting is the only symptom of head injury in a child, TBI on CT is uncommon and clinically important TBI is very uncommon.[56] TBI is more frequent in children when vomiting is accompanied by other signs or symptoms suggestive of TBI.[56]
neck pain
More commonly associated with motor vehicle collisions than with other mechanisms of injury.[57] If present, the patient should be assessed for a cervical spine injury. See Acute cervical spine trauma in adults.
normal physical neurologic exam
abnormalities on neuropsychological testing
Cognitive symptoms usually resolve quickly after mild TBI; a minority of patients have memory and concentration problems within three months of injury.[55] Neuropsychological testing involves paper-and-pencil or computerized tests assessing attention, memory, and executive functions, as well as reaction times. Routine referral for cognitive (psychometric) assessment is not recommended after mild TBI; careful assessment of the nature of the injury and symptoms, including bedside cognitive tests is more appropriate in the first instance.[55][68][69] Most guidelines support the use of formal sidelines or office-based cognitive testing for sports-related concussion.[3][5] Cognitive performance can be affected by stress, fatigue, effort, and medications. Therefore, if testing is required, neuropsychological evaluations should be carried out by trained neuropsychologists who can disentangle the effects of these factors from the consequences of mild TBI. Guidelines on sport-related concussion support the use of neuropsychological testing to diagnose the effects of mild TBI, help make return-to-play decisions for athletes, and monitor recovery.[5]
Risk factors
strong
head injury
A mild traumatic brain injury (TBI) results from a closed head injury due to a direct blow to the head or deceleration of the head from an impulsive force.[1]
previous brain trauma
Previous brain traumas lower the impact threshold, making it mild TBI more likely regardless of the force of impact and, therefore, increasing the chances of future brain trauma. This is an important risk factor in assessing outcome.[33]
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