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Is Continuous EEG Needed in the Intensive Care Unit?
Debate on the Pros and Cons

Article In Brief


“Continuous EEG remains a niche technology that not everyone is able to use and isn't supported by strong, high-quality evidence.”


In a debate about the benefits of using continuous EEG (cEEG), one neurologist argued that the technology offers prognostic value in the intensive care unit—especially for status epilepticus—while another argued that cEEG is not cost-effective or needed.

PHILADELPHIA—In almost all patients with neurological conditions who go to the intensive care unit, guidelines suggest that continuous EEG (cEEG) monitoring be utilized, mainly to detect nonconvulsive seizures. And despite the lack of strong evidence that monitoring is useful, neurologists were generally satisfied in following the expert opinion, results of voting in the Controversies in Neurology Plenary session at the AAN Annual Meeting appeared to show here.

Still, the neurologists participating in the debate offered their best arguments for both sides of the question.

“Continuous EEG remains a niche technology that not everyone is able to use and isn't supported by strong, high-quality evidence,” argued Brandon Foremen, MD, assistant professor of neurology and rehabilitation medicine and neurosurgery at the University of Cincinnati Gardner Neuroscience Institute. Dr. Foreman suggested that routine EEG is effective in patients with epilepsy, traumatic brain injury, myocardial infarction, stroke and other condition.

“Continuous EEG doesn't really matter,” he said. “Anything can be proved that it works if there isn't any evidence that it doesn't work,” he said, quoting ‘Harry Potter.’

But Emily Gilmore, MD, assistant professor of neurocritical care and emergency neurology at the Yale University School of Medicine in New Haven, said she would try to convince the audience of neurologists that they can't care for patients with status epilepticus and impaired consciousness—explained or unexplained—and acute brain injury without cEEG. “It is the cornerstone of multimodal prognostication after cardiac arrest and can detect changes heralding vasospasm after subarachnoid hemorrhage,” Dr. Gilmore said.

Her arguments won over the audience of neurologists who voted on the AAN app: 63 percent of the group agreed that cEEG in the ICU does matter, while 37 percent of the audience agreed with Dr. Foreman's argument that it doesn't.

‘No’ to cEEG

In trying to convince the audience that there was no need for continuous EEG in the intensive care setting, Dr. Foreman noted that in the European guidelines, “the strongest recommendations for continuous EEG have the lowest quality of evidence. And the rest of the recommendations are actually weaker.”

He also noted that a mere 1.7 percent of patients with cEEG in the intensive care unit with status epilepticus are actually monitored continuously to detect nonconvulsive seizures. Similarly, the recommendations suggest cEEG for patients with subarachnoid or intracerebral hemorrhage, but only 0.9 percent of these patients are actually continuously monitored. If a patient is in the intensive care unit for altered consciousness, the guidelines suggest continuous EEG, but in practice it happens 0.7 percent of the time according to a paper published earlier this year in Neurology, Dr. Foreman said.

“So cEEG has not been used on a regular basis in the 90 years since it was first discovered, and it is not being used now,” he said.

Dr. Foreman also suggested that even if one does think cEEG is important, “no one has ever shown that treating a pattern found on a cEEG actually does anything for a meaningful outcome. Sure, there is evidence that electrographic seizures and periodic discharges affect functional outcome, he said, but of course there is also evidence that it doesn't in other studies.

“But based on current evidence you can't claim that treating patients based on these findings seen on continuous EEG improves patients' outcomes.” he insisted. “What we do know is that if you hook someone up to a cEEG, you are going to start an anti-seizure drug between 14 and 43 percent of the time.” Studies show that in some cases, especially in subarachnoid hemorrhage, starting these drugs negatively affects cognition; similarly, patients with intracerebral hemorrhage report lower cognition if they were given levetiracetam to prevent seizures.

“And do we really believe cEEG is important, if the doctor reviews the EEG just a couple of times a day?” he asked. “And if I am only checking on the cEEG a couple of times a day, do I really think the nonconvulsive seizures I am missing are really that important?”

And then there is the cost, Dr. Foreman said. “Not only is EEG expensive technology, not just for the billing codes but the infrastructure required, the salaries of the technologists and the doctors to read the EEG; it is all the equipment you have to have your hospital invest in. What is the cost of liability if you miss a seizure when you are not actively watching the monitor at 2 a.m.”

“You can use routine EEG pretty effectively and without fooling yourself that you are providing continuous, real-time monitoring,” Dr. Foreman said.

‘Yes’ to cEEG

Dr. Gilmore countered that all major societies recommend cEEG as part of routine care for management of status epilepticus in critically ill patients. Updated validated recommendations from the American Clinical Neurophysiology Society contribute to a unified nomenclature that improves generalizability and interinstitutional comparability.”

She said that the reason EEG is still used clinically, “is because it is still being refined and getting better. And the reason it has been around for almost 100 years, is because it is a useful tool as an extension of what we do as neurologists.”

Dr. Gilmore said that the use of cEEG is on the rise. “The reason we are using it so much is that neurologists want to be able to diagnose things, and not just say ‘adios.’ Without knowing what is going on in the brain it makes it hard to determine what intervention to use.”

She said studies show that the majority of critically ill patients in the intensive care units are having nonconvulsive seizures across a variety of neurological illnesses and even patients in medical intensive care who do not have brain injuries have a high degree of these nonconvulsive seizure events.

Dr. Gilmore countered Dr. Foreman's contention that continuous EEG fosters the overuse of medication, arguing that it may, in fact, allow doctors to decrease drugs but identifying patients who might benefit from catheterization procedures rather than increasing medication.

“The more cEEG monitoring we do, the earlier will we get to the diagnosis on nonconvulsive status and earlier we will actually get to treat those seizures,” she said. “It also help us in escalation, re-escalation or de-escalation of interventions.

“It is not about routine EEG or continuous EEG monitoring. It is about picking the right patient, with the right etiology for whom the right intervention is actually going to impact management,” Dr. Gilmore said. “Until we have studies addressing those questions, you can't really make the argument that continuous EEG isn't necessary.

“The basis of the work that we do in every aspect of medicine, of primary and secondary prevention, is early detection which leads to early intervention which leads to improved outcomes,” she said.

Dr. Gilmore disclosed relationships with the industry-sponsored ASTRAL trial. Dr. Foreman disclosed relationships with the industry-funded Yale University NORSE Registry, Biogen, and UCB Pharma.

Link Up for More Information

•. Hill CE, Blank LJ, Thibault D, et al. Continuous EEG is associated with favorable hospitalization outcomes for critically ill patients Neurology 2019; 9(1):e9–e18.
•. Crepeau AZ, Rabinstein AA, Fugate JE, et al. Continuous EEG in therapeutic hypothermia after cardiac arrest: Prognostic and clinical value Neurology 2019;80(4):339–344.