Coma Outcome Prediction Using Event-Related Potentials: P3 and Mismatch Negativity

The prediction of the outcome from coma is of considerable importance to the patients, their relatives and attendant medical staff, and yet current clinical methods lack sensitivity and specificity. Objective investigations can enhance the accuracy of such predictions and are an important adjuvant when reaching decisions to continue or terminate life support. Of the neurophysiological methods available, electroencephalography and short-latency somatosensory evoked potentials have proved the most useful in the clinical setting. These tests are good predictors of an adverse outcome; however, they tell us only about the ongoing cerebral activity and integrity of the primary somatosensory pathways, respectively. The presence of long-latency event-related potentials has been shown to be a useful predictor of a favourable neurological outcome, and thus their use complements other neurophysiological techniques. Their potential application in clinical practice is reviewed.