Diagnosis of Idiopathic Hypersomnia

Sree Roy:

Hello, and welcome. I’m Sree Roy with Sleep Review, and I’m thrilled to be here with neurologist-sleep specialist Margaret S. Blattner, MD, PhD, who is a clinical instructor in the department of neurology at Beth Israel Deaconess Medical Center. In 2022, she won a joint Hypersomnia Foundation and AASM Foundation Strategic Research Grant for research that could ultimately improve the accuracy and utility of idiopathic hypersomnia diagnosis.

This episode is sponsored by Jazz Pharmaceuticals.

Today we are chatting about the diagnosis of idiopathic hypersomnia.

What are some barriers to diagnosing idiopathic hypersomnia?

Dr. Margaret Battner:

Absolutely. There are a number of challenges to diagnosing this condition, and unfortunately, this does lead to delays in care for patients.

So first of all, I think a big barrier is the under-recognition. This is a relatively rare disorder. Not every physician, every practitioner, is familiar with it, and a lot of the symptoms have overlap with other medical conditions and other mental health conditions that are more common and more familiar. So, under-recognition is, is one of the first barriers.

Secondly, even if idiopathic hypersomnia is the suspected diagnosis, there are limitations in our current diagnostic paradigms that lead to missed diagnoses. So, even if people with idiopathic hypersomnia make it to a sleep clinic and have a sleep clinician who is familiar with the disorder, there can still be delays in care that come from the limitations of our current diagnostic tools.

A third barrier to diagnosis and recognition is that very little is known about the pathophysiology that underlies severe daytime sleepiness in idiopathic hypersomnia. And so, there is not currently a reliable biomarker. There’s no simple clinical test, and so this limits both our diagnosis and also limits kind of recognition of this disorder by people who maybe aren’t quite as familiar.

So, together, these challenges can lead to delays in care delays and evaluation, and it can actually take years of struggling with symptoms for some people with idiopathic hypersomnia to find the answers and the care that they need.

Sree Roy:

We’ll be right back with Dr. Blattner after the short break.

This episode is sponsored by Jazz Pharmaceuticals. Jazz Pharmaceuticals is a global biopharmaceutical company with a focus in neuroscience and sleep medicine committed to improving the lives of patients and their families. Jazz is also the proud creator of sleepcountshcp.com. The goal of sleepcountshcp.com is to increase awareness of idiopathic hypersomnia and support symptom recognition to help patients receive a quality diagnosis and appropriate disease management. Sleepcountshcp.com provides evidence-based educational materials and resources to improve communication between healthcare professionals and their patients. Visit jazzpharma.com and sleepcountshcp.com for more information.

Objective sleep testing is needed to diagnose idiopathic hypersomnia. What polysomnography and multiple sleep latency test findings support a diagnosis of idiopathic hypersomnia?

Dr. Margaret Battner:

Idiopathic hypersomnia is typically diagnosed using an in-lab polysomnogram followed by a multiple sleep latency test (or a nap test) the next day.

On the multiple sleep latency test, we’re looking for evidence of excessive daytime sleepiness, which is defined as a sleep latency, or time to fall asleep, of less than eight minutes, but no excessive propensity towards REM sleep. So, this is defined as fewer than two sleep-onset REM periods. Although the MSLT has very good sensitivity and reliability in people with narcolepsy type 1, it is more limited for the diagnosis of idiopathic hypersomnia, and we know that the MSLT, though very commonly clinically used, has limited sensitivity and reliability in this condition.

Alternatively to the MSLT, idiopathic hypersomnia can be diagnosed by documentation of prolonged sleep duration. This is defined as greater than 660 minutes, either recorded on overnight extended polysomnogram or averaged over seven nights on actigraphy recordings.

However, realistically in clinical practice, these are rarely available.

Regardless of the test, context is critical in interpretation of the sleep study because the same findings can be seen in insufficient sleep, circadian rhythm disorders, and with people taking certain medications.

Because of these limitations in our current diagnostic tools, my own area of research is in how alternative diagnostic paradigms and alternative tests may help better demonstrate or better capture the excessive daytime sleepiness and prolonged sleep duration that is experienced by people with idiopathic hypersomnia. So, these are projects that we’re working on actively right now to hopefully make clinical diagnosis more efficient for people and to prevent missing people who suffer with this condition and who are just not being captured by our current testing algorithms.

Sree Roy:

What are some best practices for conducting a PSG and MSLT for a patient with suspected idiopathic hypersomnia?

Dr. Margaret Battner:

This is a very important consideration because the context of the multiple sleep latency test is so critical for accurate interpretation of this test.

One important guideline is to document adequate sleep for at least two weeks prior to the test. This can be done via actigraphy monitoring: wrist actigraphy or an activity tracker. It can also be done by keeping a careful sleep diary for two weeks prior to the sleep study. We want to make sure that people are sleeping enough, and we want to make sure that people are sleeping at times that would not result in inaccurate interpretation of the results. So, for example, if someone is habitually sleeping well into the day, this could at the time of the nap test impact the results of that sleep study.

Secondly, if the person who’s being evaluated for their sleepiness has another sleep condition such as obstructive sleep apnea, we want to make sure that the treatment for this sleep disorder is optimized before they come in for the multiple sleep latency test or the nap test. If people are using therapy for the sleep disorder, they should use that on the night of the sleep study that they come in.

The third consideration is that any medications that have alerting, sedating, or REM-modulating properties should be stopped two weeks before the sleep study, if at all possible. This comes up really commonly because common medications such as selective serotonin reuptake inhibitors, which are used to treat depression and anxiety, can modulate REM sleep. This impacts the results of the multiple sleep latency test. A conversation between the person undergoing the sleep study and the treating clinician should ideally happen before the sleep study to carefully review the medications, discuss any medications that can impact the results, and have a conversation about whether they can be stopped safely before the sleep study or not.

Unfortunately, even with best practices—so, even with documentation of adequate sleep and treating any other sleep conditions, and holding any medications that may impact the results—the overnight PSG followed by the multiple sleep latency test can still miss idiopathic hypersomnia.

Although alternative diagnostic testing to document prolonged sleep duration may actually be a more sensitive test for this condition, it can be logistically challenging, and it’s not always available at every clinic.

So again, the context, the sleep time, hiss—habitual sleep patterns, medications, and other sleep disorders—all of this context is critical for interpreting and scheduling the sleep study.

Sree Roy:

What are some of the additional commonly seen supportive features of idiopathic hypersomnia?

Dr. Margaret Battner:

Excessive daytime sleepiness is the core symptom of idiopathic hypersomnia, but one of the challenges in recognizing the condition is that additional symptoms can be variable.

For example, some people with idiopathic hypersomnia have prolonged nocturnal sleep duration of more than 9 hours per night, some people, even more than 12 hours per night, and some people have normal nocturnal sleep duration but have severe sleepiness during the day.

Other symptoms that we can see with idiopathic hypersomnia are sleep inertia, or severe difficulty waking up in the morning, associated with grogginess, impaired morning performance, sometimes saying or doing things that are nonsensical, and it can take an hour or even more for these symptoms to resolve in the morning.

Other symptoms of idiopathic hypersomnia are not as clearly sleep-related. For example, one of the most common of these is brain fog, or a sensation of cognitive clouding that can be present throughout the day, even if people are not actually falling asleep.

It’s the variable description of symptoms of idiopathic hypersomnia, all of which can impair daytime function, that make this condition one of the challenging conditions to diagnose.

Sree Roy:

Thanks so much for chatting with us about the diagnosis of idiopathic hypersomnia. You can find Sleep Review at sleepreviewmag.com. Thank you so much for tuning in to this episode.