38. Clinical and electrophysiological measures in the diagnosis of disturb of consciousness

The present research was intended to verify the relationship between traditional clinical measures (Coma Near Coma and Disability Rating Scales; CNC, DRS) to assess residual cognitive abilities in Disturb Of Consciousness (DOC) and N400 ERP index, in response to a semantic associative task. The sample was made up of 18 patients, sub-divided into two subgroups according to the clinical scorings: Vegetative State (VS) and Minimally Conscious State (MCS). They were submitted to a semantic associative auditory task that included 60 congruous (related final words) or incongruous (unrelated final words) word sequences. Results showed that all patients exhibited a N400 deflection over the fronto-central areas similar to that of healthy subjects. However this deflection was delayed in latency for incongruous word sequences. This effect was greater for VS in comparison with MCS patients, and significantly correlated with the behavioral scales, so that an increased impairment was related to a longer latency for incongruous conditions. The presence of N400 index was a strong evidence of preserved higher cognitive functions in DOC patients. However, N400 was differently modulated for VS and MCS patients. Electrophysiological measures could prevent misdiagnosis and lead to correctly classify different consciousness profiles.