Differentiated patterns of cognitive impairment 12 months after severe and moderate traumatic brain injury

Objective: To assess cognitive function at 12 months after moderate and severe traumatic brain injury (TBI) separately, as well as improvement from 3 to 12 months and relationship to global outcome. Methods: Cognitive function among patients with moderate (n = 30, Glasgow Coma Scale score (GCS) 9-3) and severe traumatic brain injury (n = 20, GCS score <= 8), recruited from an unselected neurosurgical cohort, all with MRI performed in the early phase were assessed with a neuropsychological test battery and Glasgow Outcome Scale Extended. Healthy volunteers (n = 47) matched for age, gender and years of education served as controls. Results: Executive function was reduced at 12-months post-injury in patients with both moderate and severe TBI. However, motor function, processing speed and memory were reduced only among patients with severe TBI. Both patients with moderate and severe TBI improved their processing speed and visual memory. Patients with moderate TBI also improved motor function, while patients with severe TBI also improved executive function. Conclusion: Differentiating between patients with moderate and severe TBI yields a more accurate description of cognitive deficits and their improvement over time. Further, executive dysfunction and attention problems affected the ability to resume independent living and employment regardless of injury severity and age.