Evaluating the obtunded patient after cardiac surgery: The role of continuous electroencephalography

Purpose: This prospective study was designed to evaluate the role of continuous electroencephalography (EEG) in the management of adult patients with neurological dysfunction early after cardiac surgery. Materials and Methods: Seven hundred twenty-three patients undergoing cardiac surgery between December 2010 and June 2011 were divided into 2 groups based on the presence or absence of post-operative neurological dysfunction. All patients with neurological dysfunction underwent continuous EEG. Results: Neurological dysfunction was diagnosed in 12 patients (1.7%), of whom 5 (42%) did not regain consciousness after surgery, 4 (33%) had a clinical event suspicious for seizure and 3 (25%) had neurological deficits. Continuous EEG showed that 2 of the 5 patients who failed to regain consciousness, without clinical signs of seizures, were in electrographic non-convulsive focal status epilepticus. Periodic discharges were present in the continuous EEGs of 3 patients. Three additional patients (25%) had abnormal movements that continuous EEG demonstrated was not due to seizure activity. Conclusions: Non-convulsive status epilepticus may be an under-recognized cause of obtundation early after cardiac surgery. Continuous EEG monitoring is a non-invasive test that can identify patients that may benefit from anti-epileptic medication. Larger comparative studies are required to establish whether this leads to significant improvements in patient outcomes.