Journal of neurotrauma
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Selection bias, common in traumatic brain injury research, limits the clinical usefulness and generalizability of study findings. The purpose of this study was to examine the effect of different inclusion and exclusion criteria on patient enrollment, and the implications for generalizability, in a mild traumatic brain injury (MTBI) study. The study was conducted at the emergency department (ED) of Tampere University Hospital. ⋯ The final sample and the excluded patients with MTBI significantly differed in age, mechanism of injury, and injury severity characteristics. Many studies recruit fundamentally biased samples that are not generalizable to the population of persons who sustain an MTBI. Studying carefully selected samples is often necessary to address specific research questions, but such studies have serious limitations in terms of translating research findings into clinical practice.
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Journal of neurotrauma · Jan 2013
Comparative StudyRepeated mild traumatic brain injury: mechanisms of cerebral vulnerability.
Among the 3.5 million annual new head injury cases is a subpopulation of children and young adults who experience repeated traumatic brain injury (TBI). The duration of vulnerability after a single TBI remains unknown, and biomarkers have yet to be determined. Decreases in glucose metabolism (cerebral metabolic rate of glucose [CMRglc]) are consistently observed after experimental and human TBI. ⋯ When a second mTBI is introduced during the CMRglc depression of the first injury, the consequent CMRglc is depressed (36.5%) at 24 h and remains depressed (25%) at 3 days. In contrast, when the second mTBI is introduced after the metabolic recovery of the first injury, the consequent CMRglc depression is similar to that seen with a single injury. Results suggest that the duration of metabolic depression reflects the time-course of vulnerability to second injury in the juvenile brain and could serve as a valuable biomarker in establishing window of vulnerability guidelines.