Objectives: Cognitive impairment is a common permanent sequela of traumatic brain injury (TBI). Its objectivization is based on neuropsychological and neurophysiological assessment. Neuropsychological evaluation requires a test battery, whereas for neurophysiological assessment the most significant is application of P300 Event-Related Potentials (ERPs). The aim of the study was to determine whether it is possible to differentiate between degrees of severity of TBI on the basis of neuropsychological and neurophysiological parameters.
Patients and methods: A total of 90 patients with closed TBI were evaluated at least one year after trauma. Subjects were classified into three groups according to severity of TBI: mild, moderate and severe. In all subjects the Intelligence Test, the Wisconsin Card Sorting Test (WCST) and P300 ERPs were performed.
Results: General intelligence measures did not prove sensitivity enough to differentiate levels of severity of TBI, whereas the number of achieved categories on the WCST significantly discerned patients with mild and moderate TBI from patients with severe TBI. Perseverative errors significantly separated patients with mild TBI from patients with moderate and severe TBI. Non-perseverative errors significantly differentiated only patients with mild TBI from patients with severe TBI. Finally, P300 latency (EPLAT) significantly differentiated patients with mild TBI from patients with moderate and severe TBI. The results show that the applied test battery can discriminate between different levels of severity of TBI and emphasize the importance of P300 ERP in the evaluation of patients with brain injury.
Conclusions: Our findings indicate that the WCST and ERP P300 latency have a significant role in the assessment of cognitive deficit related to TBI.