Michael Thorpy, MD, director, Sleep-Wake Disorders Center, Montefiore, and professor, Neurology, Albert Einstein College of Medicine, discusses diagnostic components of idiopathic hypersomnia and emerging methods of treatment.
As a newly recognized disorder, idiopathic hypersomnia is characterized by excessive daytime sleepiness and potentially long nocturnal sleep time, with current methods of treatment leveraging therapies indicated for similar conditions such as narcolepsy, said Michael Thorpy, MD, director, Sleep-Wake Disorders Center, Montefiore, and professor, Neurology, Albert Einstein College of Medicine.
Can you discuss the heterogeneous nature of idiopathic hypersomnia? What are some current methods to evaluate its severity in patients?
Idiopathic hypersomnia is a relatively newly recognized disorder. Although some components of idiopathic hypersomnia have been known for many years, there’s been a little bit of confusion about the diagnostic criteria.
At one stage it was divided into 2 types: patients who had excessive daytime sleepiness with long sleep time, and patients who had excessive sleepiness that was independent of a long nocturnal sleep time. And more recently, the 2 types of idiopathic hypersomnia have sort of come down to one diagnostic category. There is a move to actually go back to the earlier diagnostic category of dividing into 2 separate types, but that’s in the proposal stage at this point.
So, idiopathic hypersomnia are basically people who have excessive daytime sleepiness, who don't meet the criteria for any other disorder of excessive sleepiness, such as narcolepsy or sleep deprivation or anything else.
So, in a way, it's sort of like an exclusion diagnosis. Patients who have idiopathic hypersomnia tend to have either a long nighttime sleep episode, in which case they may also have some sleepiness during the daytime.
Typically, under the new criteria, they need to sleep at least 11 hours at night in order to meet the criteria, but then there are other patients who don't have that long sleep episode and have a normal sleep duration at night, but are still sleepy during the daytime that don't have the typical features of narcolepsy—so can't be categorized as having narcolepsy.
There has never been a treatment for patients with idiopathic hypersomnia that's been FDA approved. And so most of the drugs that are used or medications that are used to treat narcolepsy have been applied to patients with idiopathic hypersomnia, but now, we have a first study of a drug for idiopathic hypersomnia that has entered into phase 3 studies that have now been completed. It shows an indication to be effective for the treatment of excessive sleepiness and patients with idiopathic hypersomnia.