Inclusion criteria were (1) having sustained MTBI and (2) age 16.0–59.9 years. The upper limit was chosen since participants were also invited to MRI, and the burden of non-traumatic abnormalities increases with age, making it more difficult to study the impact of the MTBI. We applied the recent definition of TBI, defining TBI as “an alteration in brain function, or other evidence of brain pathology, caused by an external force” [23 (link)]. In the present study, these criteria were operationalised as follows: we included patients who had experienced a physical trauma towards the head or high energy trauma, if either (1) witnessed loss of consciousness (LOC) or confusion and/or (2) self-reported amnesia for the event or the time period after the event, and/or (3) a traumatic brain lesions on CT was reported. Next, cases identified with TBI were further categorised as mild (MTBI) if they met the WHO criteria for being mild: Glasgow Coma Scale (GCS) score 13–15 at presentation, LOC < 30 min, and posttraumatic amnesia (PTA) < 24 h [1 ]. Evaluation of intoxicated patients represented a challenge, and we sought to be confident that their self-reported amnesia was a result of MTBI and not intoxication. Therefore, only patients who had been observed by the people accompanying them as fully conscious prior to the injury, or who reported complete memory for events immediately prior to the injury, were considered to have a MTBI.
MTBI was the chosen term in this study, acknowledging that the term “concussion” may be more common in the sports medicine literature [7 (link)]. Exclusion criteria in the Trondheim MTBI follow-up study were late presentation or presence of co-morbidities or circumstances that would make it very difficult to follow-up patients or where a valid MTBI-related outcome could not be obtained: (a) non-residency in Norway or non-fluency in the Norwegian language, (b) ongoing, severe psychiatric disease, severe somatic disease or drug abuse; that would complicate follow-up, (c) history of complicated mild, moderate or severe TBI or other neurological conditions with brain pathology visible on imaging or known cognitive deficits, (d) presentation > 48 h after the initial trauma, and (e) other concurrent major trauma, such as spinal cord injury, severe fractures or internal injuries.
MTBI was the chosen term in this study, acknowledging that the term “concussion” may be more common in the sports medicine literature [7 (link)]. Exclusion criteria in the Trondheim MTBI follow-up study were late presentation or presence of co-morbidities or circumstances that would make it very difficult to follow-up patients or where a valid MTBI-related outcome could not be obtained: (a) non-residency in Norway or non-fluency in the Norwegian language, (b) ongoing, severe psychiatric disease, severe somatic disease or drug abuse; that would complicate follow-up, (c) history of complicated mild, moderate or severe TBI or other neurological conditions with brain pathology visible on imaging or known cognitive deficits, (d) presentation > 48 h after the initial trauma, and (e) other concurrent major trauma, such as spinal cord injury, severe fractures or internal injuries.
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