Reading EEGs

A few days ago, I wrote a post on the use of continuous EEG in the ICU. I mentioned that intensivists should know some of the basics of reading EEGs. I am far from an expert in this. I have learned a few basic things. Mostly what we’re doing at this level with EEG is looking for seizures, specifically subclinical seizures. I think a good way to think of the EEG in this regard is similar to what I first learned about neurocritical care in general. Having come from a cardiac surgery background, an intensivist I worked with said, “think of everything we do in the CTICU, then do the opposite.” Not completely true, but it helped me!

I do something similar with EEGs. I compare them to ECGs. And if they look anything like ECGs, that’s bad. Brain wave activity should be much more random than cardiac electrical activity. So, an EEG that is rhythmic like an ECG is likely to be seizures. At the very least, it’s abnormal. Likewise, flat lines on ECGs represent asystole (bad) and flat lines on EEGs represent the absence of brain activity. Now, sometimes, we want this, as in when we’ve induced burst suppression to help deal with ICP crisis. But, absent that, flat lines on EEGs are usually a bad thing.

Now, of course you can learn a lot more from an EEG than that. If you’re interested in learning more about of EEGs work and the basics of how to read them, Nizam Ahmed has a really nice series of YouTube videos. I think there are about 10 of them in total, but they’re each pretty short and great for microlearning. So, check them out and delve a little more into what the EEG means. And, if you don’t really feel the need to read the squiggly lines yourself, but need some help making heads or tails out of the EEG report, Casey Albin and Neha Dangayach have you covered.

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