Retest reliability of event-related potentials (ERP) in unresponsive patients

Clinical experience suggests that patients with severe disorders of consciousness (DOC) due to brain injury, i.e. vegetative state (PVS) or minimally conscious state (MCS) do not have constant performance levels but show large variations in their behavioral abilities. Novel diagnostic approaches using fMRI or ERPs attempt to detect traces of consciousness even if clinical ratings imply unresponsive wakefulness. It is especially important for such sensitive methods to be aware of possible consciousness fluctuations in DOC patients in order not to measure at the wrong time. We elicit ERPs during an auditory oddball task using a 256 channel high-density EEG system in patients with DOC during inpatient neurorehabilitation. To estimate retest reliability of ERPs, we tested the patients longitudinally 2 times per day for 2 days and correlated that with behavioral testing using the Coma Recovery Scale – revised. Data from 10 individual patients in VS or MCS will be presented. At the time of abstract submission, already 5 patients have completed testing. 1 MCS and 2 VS patients showed a P300 response, which was stable across all testing sessions. Literature: Amantini A, Carrai R, Fossi S, Pinto F, Grippo A (2011). The role of early electronical assessment in improving the evaluation of patients with disorders of consciousness. Funtional Neurology, 26 , 7 – 14. Balconi M (2011). State of consciousness and ERP (event-related potential) measures. Diagnostic and prognostic value of electrophysiology for disorders of consiousness. Neuropsychological Trends, 9 – 10 , 43 – 54. Patel SH, Azzam PN (2005). Characterization of N200 and P300: Selected Studies of the Event-Related Potential. International Journal of Medical Science, 2 , 147 – 154. doi:10.7150/ijms.