If you have ever seen someone in an intensive care unit (ICU), you have seen a lot of wires and monitors. When the patient has a brain injury there are even more. Electrodes are placed all over their head to monitor brain waves. This is called Scalp Electroencephalography (EEG) and doctors routinely use it to detect seizures and changes in brain function. A new form of EEG, Intracortical EEG (ICE for short), used inside the brain itself is emerging as a safe alternative with the potential to help many more patients.
A recent study published in the Annals of Neurology sheds new light on the potential of ICE in the ICU. Dr. E. Sander Connolly from the Cerebrovascular Center and his colleagues compared the use of Scalp EEG to ICE in sixteen patients with critical brain injury.
What they found was that the use of this in-brain device was much more sensitive than Scalp EEG and despite being invasive, caused no ill effects. The use of ICE also overcame a number of problems associated with Scalp EEG such as electrode movement, poor signal-to-noise ratio, and artifact picked up from all the other devices around the patient in the ICU.
ICE readings showed as much a five times greater signal amplitude and many of the seizures detected were not even registered by the scalp EEG. These seizures that were picked up are called “clinically silent” because the patient doesn’t move. In this study nearly all the patients with brain injury showed these types of brain seizures. It has not been proven that seizures are causative or just associated with damage but according to the authors, “clinically silent seizures identify a potential treatable source of ongoing brain dysfunction and progressive injury.” If it is proven to be the case that the seizures are causative then having a more sensitive monitoring device such as ICE will enable doctors to administer drugs that can control them.
For two of the patients, event detection preceded the other monitoring devices by at least several hours.
The authors say, “ultimately, we predict that this technique will play a central role in the detection and prevention of secondary neuronal injury, and potentially improve outcomes, in patients with critical neurological injuries.” The authors urge that future studies need to be done to maximize the potential of this procedure. “The improved data quality from intracortical recordings may be instrumental in the continued development of real-time “neurotelemetry” and automated EEG-based alarm systems.”
This article, Intracortical Electroencephalography in Acute Brain Injury, can be found in the Annals Of Neurology 2009, Volume 66, Issue 3.
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