Cognitive impairment 3 months after moderate and severe traumatic brain injury: a prospective follow-up study

Objective: To explore the magnitude and frequency of cognitive impairment 3 months after moderate to severe traumatic brain injury (TBI), and to evaluate its relationship to disability at 1-year follow-up.

Design: Prospective follow-up study.

Setting: Regional level I trauma center.

Participants: Patients aged 15 to 65 years with definite TBI, defined as Glasgow Coma Scale score of 3 to 13 and injury documented by magnetic resonance imaging (n=59) or computed tomography (n=2); healthy volunteers (n=47) served as controls.

Interventions: Not applicable.

Main outcome measures: Neuropsychological assessment 3 months postinjury and Glasgow Outcome Scale Extended (GOSE) at 3 and 12 months postinjury.

Results: Patients with TBI performed worse than controls, most consistently in terms of information processing speed and verbal memory. However, a maximum of only 43% of patients with TBI had impaired test scores (defined as <1.5 SD below mean of normative data) on any one measure. Based on a selection of 9 tests, a 0 or 1 impaired score was seen in 46 (98%) of 47 controls, in 20 (57%) of 35 patients with moderate TBI, and in 9 (35%) of 26 patients with severe TBI. At 1 year postinjury, disability (defined as GOSE score ≤6) was present in 57% of those with 2 or more impaired test scores and in 21% of those with 0 or 1 impaired score (P=.005).

Conclusions: In this sample of patients with recent, definite TBI and healthy volunteers, we found that TBI affected cognition in moderate as well as severe cases. The presence of cognitive impairment was associated with future disability. However, half of the patients with moderate TBI and even one third of those with severe TBI had a normal cognitive assessment 3 months postinjury.