P300 after minor head injury (a follow-up examination).

ABSTRACT

BACKGROUND AND METHODS: The aim of the study was to examine whether--like in severe head injuries--the endogenous evoked potential P300 is influenced by minor head injury (MHI) and how the eventual abnormalities develop within a follow-up period of 8 weeks after trauma. Therefore we examined the cognitive auditory evoked potential P300 (latency, amplitude), the neurologic state and the performance in psychometric testing (Mini-Mental-State, Number Connection test part A and B) in 15 patients within the first 24 hours as well as 1, 3 and 8 weeks after MHI. The P300 results were compared to the age-related normal ranges under consideration of the intra-individual variability. For both parameters normative values were established before in our own laboratory. RESULTS: For the patient group as a whole the mean values for P300 latency and amplitude were always within the age-related normal range and normal intra-individual long-term variability of healthy controls, respectively. Significant posttraumatic prolongations of P300 latency were exclusively observed in the only 20% of our patients with clinically suspected posttraumatic organic brain syndrome. These prolongations of latency decreased during follow-up and on the last examination the latencies were normalised. Compared to psychometric tests, P300 latency seems to be more sensitive in early detection of cerebral dysfunction. CONCLUSIONS: We conclude that, in contrast to severe head injury, in general the P300 is not affected by minor head injury. If there are clinical signs of organic brain syndrome following MHI posttraumatic prolongation of P300 latency is a marker of cerebral dysfunction and may serve as a valuable parameter for follow-up examination and documentation.