4. Neurophysiological pattern related to recovery of responsiveness in patients with disorders of consciousness after cardiac arrest

Most of the patients who survive after a cardiac arrest (CA) recover responsiveness in the first 30–40 days, even if further recovers are possible also in the following months. We conducted a prospective study to correlate the recovery of consciousness with EEG and somatosensory evoked potentials (SEP) findings. The level of consciousness was evaluated by means of the Coma Recovery Scale Revised. 22 inpatients (12 VS, 6 low grade MCS, 4 high grade MCS) were followed for a mean of 200 days (range 112–300 days) since CA. EEG and SEPs were recorded within 1 week from the admission and every 4 weeks. At the end of the follow-up, 2 patients had died, 7 VS patients did not recover consciousness, 4 VS patients became low grade MCS and 1 VS patient became high grade MCS; 5 MCS patients did not change their clinical condition; 1 low grade MCS and 4 high grade MCS patients recovered consciousness. Only patients with present SEP recovered consciousness. No EEG pattern is able to predict no recovery of consciousness, whereas reactive EEG correlated with a clinical improvement. If epileptiform discharges are found (even after 2 months after CA), a recovery of consciousness is still possible.