P300 AFTER MINOR HEAD-INJURY (A FOLLOW-UP EXAMINATION)

Background and methods : The aim of the study was to examine whether - like in severe head injuries - the endogenous evoked potential P300 i s influenced by minor head injury (MHI) and how the eventual abnormali ties develop within a follow-up period of 8 weeks. after trauma. There fore 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 1 5 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 para meters normative values were established before in our own laboratory. Results : For the patient group as a whole the mean values for P300 l atency and amplitude were always within the age-related normal range a nd normal intraindividual long-term variability of healthy controls, r espectively. Significant posttraumatic prolongations of P300 latency w ere exclusively observed in the only 20% of our patients with clinical ly 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 latenc y seems to be more sensitive in early detection of cerebral dysfunctio n. 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 m ay serve as a valuable parameter for follow-up examination and documen tation.