A diagnosis of Disorders of Consciousness (DOC) is difficult to provide, because clinical examination is limited in these unresponsive DOC patients. Available standardized tools specifically developed for the evaluation of patients with severe impairment are very limited and mostly relatively insensitive to minor changes in level of consciousness. Based on the evidence to-date, electroencephalographic assessments of consciousness provide valuable information for evaluation of residual functions, formation of differential diagnoses, and estimation of prognosis. Specifically, ERPs (Event-Related Potentials) might be used to assess consciousness, providing an on-line monitoring of information processing in the brain. The present research explored the relationship between different measures of DOC, that is electrophysiological measures (ERP N400 effect) and clinical measures (Coma Near Coma, CNC; Disability Rating Scale, DRS). This analysis aimed to verify the preservation of semantic linguistic processes in eighteen DOC patients. MCS (Minimally Conscious State) and VS (Vegetative State) patients were compared with respect of N400 amplitude and latency measures. They were submitted to an associative auditory task that included congruous (related final words) or incongruous (unrelated final words) word sequences. Firstly, an increased N400 peak amplitude within the fronto-central cortical areas was revealed in response to incongruous sequences for all patients. Moreover, this peak was temporally delayed in response to incongruous conditions in these cortical sites. In addition, VS patients showed a delayed N400 in comparison with MCS patients in incongruous condition. Moreover, a direct correlation was found between the clinical scales (both CNC and DRS) and the ERP modulation, in term of peak amplitude and latency. Thus the present results were discussed taking into account the significance of N400 as a marker of semantic processes in DOC patients. Secondly, it was underlined that this semantic cognitive covert process may be demonstrated also in patients that show significant impairment in overt behavior (as in VS or MCS). Finally it was suggested to use ERP measure to improve the diagnostic profile in case of DOC patients.
|Number of pages||1|
|Publication status||Published - 2013|
|Event||XXI Congresso Nazionale della Società Italiana di Psicofisiologia - Lecce|
Duration: 24 Oct 2013 → 26 Oct 2013
- Disorders of Consciousness
- Semantic association