Primary objective: The purpose of this study was to carefully examine the effects of a complicated vs uncomplicated mild traumatic brain injury (MTBI) on acute neuropsychological outcome.
Research design: Participants were derived from an archival trauma database. This is a retrospective matched groups design.
Methods and procedures: All patients were seen through a Head Injury Trauma Service clinical pathway. To be included, all patients must have undergone a day-of-injury CT scan and completed a small battery of neuropsychological tests within 2 weeks of injury. Patients were sorted into two groups on the basis of having a normal or abnormal CT scan. Patients were then carefully matched on age, education, gender and mode of injury (e.g. car accident, fall or assault). The final sample consisted of 100 patients, with 50 in each group.
Main outcomes and results: The patients with complicated MTBIs performed significantly more poorly on some of the neuropsychological tests. However, the effect sizes were small or medium and the two groups could not be differentiated using logistic regression analysis.
Conclusions: The reasons why people recover slowly or fail to recover fully from MTBIs remain poorly understood. Visible structural brain damage carries increased risk for slow and incomplete recovery, but certainly does not provide an explanation for good or poor outcome in the majority of patients.