Objective: To compare evoked potential (EP) and electroencephalogram (EEG) recordings from patients with suspected mild traumatic brain injury (TBI) versus normal controls using computerized EP and EEG analysis procedures. Design: Matched two-group comparison design, with a second matched replication group, and a second group of normals. Setting: Private, ambulatory, non-emergency facility specializing in assessment, pain management, and rehabilitation of spine and related injuries. Patients and Other Participants: Patients were 54 consecutive referrals for computerized EP/EEG evaluation with histories of primarily motor vehicle accidents and symptoms consistent with mild TBI. Normal controls were 27 screened volunteers. Patients were arbitrarily divided into two groups and matched to the controls on the basis of age and gender. Main Outcome Measures: Outcome measures not included in this phase of investigation. Auditory and visual EPs were obtained in resting and P300 task sessions (in which subjects counted the number of randomly occurring target stimuli). The paucity of existing Literature did not permit prediction of all critical EP or EEG variables. Results: Middle latency EP components tie, after brain stem responses yet before long latency, cognitive components) showed amplitude increases (auditory P1, P2, and N2, and visual P2, 50-220 milliseconds poststimulus). Long latency cognitive components (auditory and visual P300 and N3, 290-700 milliseconds) showed amplitude decreases. Similar findings were present in the replication group of patients and in comparison to a second group of normal controls. Conclusions: Significant and reliable EP differences were present in patients whose histories and symptoms were consistent with mild TBI.
