A friend asked me this, and I said I’d ask here, where people have an astonishing breadth of knowledge…
He’s going in to see a neurologist (I have no idea why) and the doc said for him to stay awake for at least eight hours before the office visit.
How come? What’s the difference, neurologically, between having been awake for the last, say, three hours, or five hours, and eight hours? And how wide awake? Lying in bed and reading – that’s a very low level of consciousness, not too removed from sleep. Or watching TV: one can zone out on the History Channel and hardly count as awake at all.
What is the doctor getting at here? I’ve heard of fasting before a blood test, but staying awake before a neuro. exam? Huh?
But I’ll second the OP’s observations. I was sitting in a neurologist’s office one day, and I overheard the assistant or somebody instructing another patient – I think it was in preparation for an EEG exam the following day – and the instructions included something about staying awake for some long period of time, like overnight or something.
ETA: Wait! It gets worse! When my exam time came (it was just a consultation), instead of escorting me into the doctor’s little office, they took me into the “procedure room” by mistake, and let me sit there for a while until the doctor came looking for me. There was a rack on the wall with a collection of instruments of torture hanging from it – they looked like electrodes of various sizes and shapes.
There was a cabinet of drawers, with labels on the front telling what was in each drawer. One drawer had “EMG [electromyogram] Needles” on the front left side of the drawer, and “Ammonia Ampules” on the front right side. //eek//
(And…ah…I might just manage to neglect to convey the rest of your post to my friend… Instruments of torture, hm? I thought those were only used in dentistry!)
Sleep-deprived EEGs are pretty standard for diagnosing epilepsy. But I wouldn’t think that just staying awake for the eight hours before the exam qualifies, unless his appointment is at 7AM or something.
Can you tell us anything more about how that’s supposed to work? Is the patient more likely to have a seizure when sleep-deprived?
I read somewhere that EEGs can only detect epilepsy if you manage to catch a seizure in progress. It’s not like electrocardiograms, which can detect a heart attack long after the actual event. (I once had an electrocardiogram that “detected” a heart attack, apparently well after the fact, that I never knew of. The doctor said that was most likely a false alarm and that such were common, and don’t worry about it.)
I don’t know how exactly EEG’s detect epilepsy, but I had seizures as a child and I can confirm that I was sleep-deprived before getting my annual EEG.
All of my seizures occurred either as I was falling asleep or as I was waking up. I don’t think that I had any as I was sleeping but I’m not actually positive. Since they all occurred around sleep-time, I don’t remember any of them.
Because of this, the night before I was scheduled to have an EEG, my parents would always let me stay up late and try to pull an all-nighter. That way I would be dead tired and fall asleep for the EEG. I think the idea was for the EEG to be performed during the time when seizures were most likely to occur.
As I said, I don’t know exactly what the EEG detected. But I do know that I would have a follow-up visit with the neurologist a week or so later and he would identify periods of “abnormality” in the EEG, which I presume is when seizures were most likely. Based upon the EEG results, my medication would be adjusted.
As an aside, before actually letting me fall asleep, they would try to induce seizures in other ways. So they would flash a strobe light in my eyes for a minute or two, then try to make my hyperventilate for a minutes or two. I think there was a couple other tests too. Stuff that would wake me up, essentially. Then they’d tell me to fall asleep. Wasn’t always easy.
Yeah, pretty much. Stress, physiological or psychological, can lower the seizure threshold. Even someone very conscientiously taking medication that generally provides good seizure control can have breakthrough seizures during a time of increased stress. My mom’s only had 1 seizure in the past 20+ years, and that was while Daddy was being stabilized for bypass surgery after a massive heart attack. Not eating well, trying to sleep in a chair in the CCU waiting room, worrying herself sick–with all those factors combined, it’s a wonder she made it two days before finally having a seizure.
And yes, they really want you to have a seizure while you’re wired up. They want to be able to see how long the seizure lasts, if you have involuntary movements, what part or parts of the brain it happens in, anything and everything they can find out. So they sleep deprive you, and then a certain way into the test they’ll start flashing lights at you, steadily increasing the speed and intensity.
