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

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.

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.

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.

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.