Dr. Thorpy:
This is CME on ReachMD and I'm Dr. Michael Thorpy. Here with me today is Dr. Clete Kushida. We're discussing challenges to recognizing and diagnosing narcolepsy. 

Now the main symptoms of narcolepsy I'd like to think of as being 3 different types, excessive daytime sleepiness, abnormal REM sleep phenomena, which cataplexy is one, and disturbed nocturnal sleep.

Clete, sleepiness isn't all the same in narcoleptics, is it? It can be quite different. 

Dr. Kushida:
Yes, absolutely. So you can have, as shown on this slide, the background level of sleepiness, but you can also have naps and sleep attacks, which are these sudden, irresistible need for sleep where the person doesn't really have control, almost. They go directly into sleep. And as you can see, you know, naps can be very refreshing, but sometimes there can also be automatic behaviors where the person might be doing something, like talking or writing, and there'll be some persistence of that behavior as they have the sleepiness attack.

Dr. Thorpy:
So just asking a patient, you know, do you fall asleep in front of television isn't enough. You really need to go in a little bit more detail to try to understand the different features of sleepiness that that patient might be experiencing. 

Dr. Kushida:
Absolutely.

Dr. Thorpy:
Now the second major component is disturbed nocturnal sleep. Many of these patients have disturbed sleep, don’t they, Clete? What are some of the main features of that disturbed sleep? 

Dr. Kushida:
Yes. So we know that individuals with narcolepsy have fragmented sleep, and what happens is it can reduce the total sleep time. It can also sort of chop up the REM sleep, and as shown here, what happens is, because of these frequent awakenings or brief awakenings which are called arousals, the sleep is very heavily fragmented, and that in turn can lead to significant daytime sleepiness as well. 

Dr. Thorpy:
Sometimes an overnight sleep study can be helpful in diagnosing narcolepsy because you can differentiate from somebody who is sleep deprived to somebody with narcolepsy. I mean, narcoleptics obviously may go into the REM sleep quickly and go into sleep very quickly at night. They may also have more lighter stage 1 sleep.

Now the other main feature of narcolepsy is the normal REM sleep phenomena, and cataplexy is obviously a main one and we'll discuss that in just a minute. But there are other features of disturbed REM sleep, both in the type 1 and the type 2 narcoleptic patients, aren't there? So they may not necessarily have cataplexy, but they can have abnormal REM sleep phenomena occurring either at night or during the daytime.

So can you tell us a little bit about some of those features of disturbed nocturnal REM sleep?

Dr. Kushida:
Thank you, Michael. So one of the things that can occur is this thing called sleep paralysis where it's almost like the persistence of the suppression of muscle activity during REM sleep that carries on as they're going in and out of sleep. And so what happens is the person has paralysis of their voluntary muscles, and in addition, it can sometimes be accompanied by hallucinations, and these can be visual. It can also be somatic as well as auditory. And I always tell this story about one of my patients, that she would be drifting off to sleep and then she would see her husband come in with a knife, coming at her, and she couldn't move. And that's a classic example of a visual hallucination coupled with the sleep paralysis.

Dr. Thorpy:
Right. And they can also have REM sleep behavior disorder where they actually have a lot of movement activity during REM sleep at night too. So there are a lot of features of disturb REM sleep that a clinician should ask the patient about and get a clearer idea of what's going on there.

But of course, the main REM sleep phenomena is cataplexy, isn't it? And cataplexy is pathognomonic for narcolepsy, only seen, of course, in the type 1 narcoleptic patients. But tell us more about cataplexy, Clete.

Dr. Kushida:
Yeah. So cataplexy is a sudden drop in muscle tone that's frequently triggered by strong emotions, such as laughter, anger, and surprise. And as shown here, this muscle tone decrease can be something very slight. It can be like just drooping of the eyelids or head drop, or it can even be involving the whole body, where the person falls to the ground. But most commonly it's more partial or localized.

Dr. Thorpy:
But it's difficult to make the diagnosis. You need to consider other things in the differential diagnosis of narcolepsy. Sleep deprivation, of course, is one of the most important things. Many of these patients have sleep apnea and so that needs to be excluded. And there's a delay in sleep phase, circadian rhythm disorders that can occur in narcoleptic patients.

Well, this has been a great bite-size discussion, but our time is up. Thank you for listening.