Deep brain stimulation for narcolepsy: proof of concept in mouse model

Emory neurosurgeon Jon Willie and colleagues recently published a paper on deep brain stimulation in a mouse model of narcolepsy with cataplexy. Nobody has ever tried treating narcolepsy in humans with deep brain stimulation (DBS), and the approach is still at the “proof of concept” stage, Willie says.

People with the “classic” type 1 form of narcolepsy have persistent daytime sleepiness and disrupted nighttime sleep, along with cataplexy (a loss of muscle tone in response to emotions), sleep paralysis and vivid dream-hallucinations that bleed into waking time. If untreated, narcolepsy can profoundly interfere with someone’s life. However, the symptoms can often be effectively, if incompletely, managed with medications. That’s why one question has to be: would DBS, implemented through brain surgery, be appropriate?

The room where it happens. Sandwiched between the thalamus and the pituitary, the hypothalamus is home to several distinct bundles of neurons that regulate appetite, heart rate, blood pressure and sweating, as well as sleep and wake. It’s as if in your house or apartment, the thermostat, alarm clock and fuse box were next to each other.

Emory audiences may be familiar with DBS as a treatment for conditions such as depression or Parkinson’s disease, because of the pioneering roles played by investigators such as Helen Mayberg and Mahlon DeLong. Depression and Parkinson’s can also often be treated with medication – but the effectiveness can wane, and DBS is reserved for the most severe cases. For difficult cases of narcolepsy, investigators have been willing to consider brain tissue transplants or immunotherapies in an effort to mitigate or interrupt neurological damage, and similar cost-benefit-risk analyses would have to take place for DBS.

Willie’s paper is also remarkable because it reflects how much is now known about how narcolepsy develops. Read more

Posted on July 16, 2020 by Quinn Eastman in Neuro Leave a comment

Head to head narcolepsy/hypersomnia study

At the sleep research meeting in San Antonio this year, there were signs of an impending pharmaceutical arms race in the realm of narcolepsy.

The big fish in a small pond, Jazz Pharmaceuticals, was preparing to market its recently FDA-approved medication: Sunosi/solriamfetol. Startup Harmony Biosciences was close behind with pitolisant, already approved in Europe. On the horizon are experimental drugs designed to more precisely target the neuropeptide deficiency in people with classic narcolepsy type 1 (for narcolepsy with cataplexy: hypocretin/orexin agonists).

Amidst this commercial maneuvering, a new clinical trial is underway at Emory Sleep Center. The study compares modafinil versus amphetamines for narcolepsy type 2 (NT2) and idiopathic hypersomnia (IH).

These are not new drugs; they are old standards, when used to treat other sleep disorders. What’s remarkable here is that they are being tested “head-to-head.” In addition, the study explicitly tracks outcomes that people with NT2 and IH often talk about: sleep inertia, or difficulty waking up and getting out of bed in the morning, and brain fog, which is difficulty thinking/concentrating/paying attention. The main outcome measure is the Epworth Sleepiness Scale, which asks how likely someone is to fall asleep during daytime situations such as reading or while stopped in traffic. Read more

Posted on June 20, 2019 by Quinn Eastman in Neuro Leave a comment

A life consumed by sleep

Nothing he tried had worked. For Sigurjon Jakobsson, the trip to Atlanta with his family was a last-ditch effort to wake up. He had struggled with sleeping excessively for several years before coming from Iceland to see a visionary neurologist, who might have answers.

In high school, Sigurjon was a decathlete competing as part of Iceland’s national sports team. But at the age of 16, an increasing need for sleep began to encroach upon his life. Sigurjon needed several alarm clocks to get out of bed and was frequently late to school or his job at a construction company. He often slept more than 16 hours in a day.

Sigurjon feeling awake (Atlanta, summer 2018)

When Sigurjon describes his experiences, they sound like depression, although his mood and lack of motivation appear more a consequence of his insatiable desire to sleep. He quit sports. He dropped out of college and became isolated and lost touch with close friends.

“Your will to do things just kinda dies,” he says. “And then you’re always trying and trying again. It just gets worse. You kinda die inside from being tired all the time.”

At the recommendation of a neurologist in Iceland, Sigurjon’s family sought out David Rye, who is known internationally for his research on idiopathic hypersomnia, a poorly understood sleep disorder. Read more

Posted on February 11, 2019 by Quinn Eastman in Neuro Leave a comment

Measuring sleepiness: alternatives to five naps

In a 2015 episode of The Simpsons, Homer is diagnosed with narcolepsy. Overwhelming sleepiness at the nuclear power plant lands him in the hospital. Sampling his spinal fluid (ouch!), Homer’s chuckling, deep-voiced doctor quickly performs a test for hypocretin, a brain chemical important for staying awake and regulating REM sleep.

Reality check: testing for hypocretin takes time, and is not currently available in the United States. Let’s talk about how sleep disorders such as narcolepsy and idiopathic hypersomnia are actually diagnosed: operationally, rather than biologically. The less flashy, but standard, way to assess patients is to ask them to take a series of five naps and see how fast they doze off, and how fast they go into REM sleep (the rapid eye movement dreaming phase).

This process, known as the Multiple Sleep Latency Test or MSLT, works pretty well for narcolepsy type 1, the more distinctive form of narcolepsy that includes cataplexy. And it’s hard to fake being sleepy enough to zonk out within a few minutes. But it has a bunch of problems, and dissatisfaction with the MSLT has been developing among sleep specialists for the last several years.

Lynn Marie Trotti, MD

At Emory, neurologists Lynn Marie Trotti and David Rye published an analysis of what I will call the “flip flop problem” in 2013, with others in the field following up more recently. The flip flop problem is: someone who takes the MSLT one day will frequently get another result if they take it again on a different day. Read more

Posted on June 29, 2018 by Quinn Eastman in Neuro 1 Comment

How much does idiopathic hypersomnia overlap with ME/CFS?

In everyday linguistic usage among non-specialists, sleepiness can blend together with tiredness and fatigue. Someone might feel “tired” after climbing a mountain or chopping down a tree, while “sleepiness” is different. Emory sleep scientists explore the pathological distinctions in a paper published in Journal of Sleep Research.

A team led by neurologists Lynn Marie Trotti and David Rye has been studying idiopathic hypersomnia (IH) for several years: people who experience excessive daytime sleepiness and “sleep drunkenness,” not explained by other medical conditions.

IH’s symptoms don’t usually include persistent muscle pain or a severe response to exertion. This separates the disorder from myalgic encephalomyelitis, also known as chronic fatigue syndrome (ME/CFS). But there is some overlap, which is what neurology resident Caroline Maness, Trotti and colleagues report in the new paper. The authors use the official term SEID (systemic exertion intolerance disease), which was recommended by an Institute of Medicine panel in 2015, but hasn’t really stuck among those in the ME/CFS field.

Some people with IH have disclosed that they were previously diagnosed with ME/CFS. Outside of the sleepy vs tired issue, some people with IH report symptoms shared with ME/CFS, such as impaired circulation in their extremities in response to cold, or dizziness upon standing. Speculatively, this may point to a possible problem with the autonomic nervous system. Trotti and a collaborator at Stanford, Mitchell Miglis, are now examining this issue further.

ME/CFS has had a history of controversy. Despite its devastating impacts, some have viewed it as psychological or somehow unreal, and sufferers have felt neglected or maligned by mainstream medicine. The National Institutes of Health has made efforts to turn that situation around by investing in ME/CFS research, and there has been a surge of attention recently covering ME/CFS (Amy Maxmen items in Nature, Stanford magazine feature, Unrest documentary).

Trotti, Maness and colleagues didn’t set out to dive into ME/CFS – they explicitly label this paper a pilot study, and the results say more about the “hypersomnolent” group of patients they have been seeing for the last several years, rather than the broader ME/CFS population. Read more

Posted on April 16, 2018 by Quinn Eastman in Neuro Leave a comment

Momentum at hypersomnia conference

A visitor might not realize this was a meeting devoted to people who experience excessive daytime sleepiness. The 2015 Hypersomnia Foundation Conference on Saturday was full of energy, with:

*more than 245 attendees, about twice as many people as last year’s conference

*medical experts from France, Wisconsin and Louisiana — in addition to Emory

*data from several recent clinical trials

*some signs of industry interest in hypersomnia

Hypersomnia is a sleep disorder in which individuals feel frequent or constant sleepiness and need to sleep for long portions of the day (more than 70 hours per week). It is distinct from other sleep disorders such as narcolepsy and sleep apnea, but its prevalence is still unclear. Conventional stimulants such as amphetamine or modafinil often can be used to treat the sleepiness, but some with hypersomnia find these drugs ineffective or hard to tolerate.

Previous research at Emory has shown that many individuals with hypersomnia have a substance in their spinal fluid that acts like a sleeping pill, enhancing the action of the neurotransmitter GABA. The identity of this mysterious substance is unknown, but Emory researchers report that they are close to identifying it. That could give hypersomnia a “molecular handle” similar to what narcolepsy has, with loss of hypocretin-producing neurons.

The terminology is still up in the air — keynote speaker Isabelle Arnulf from Paris said, “The term ‘idiopathic hypersomnia’ does not mean that you are an idiot.” Rather, she said, it means that even specialists can have trouble distinguishing hypersomnia from other sleep disorders, and “idiopathic” signifies that the detailed cause is still under investigation.

Posted on July 22, 2015 by Quinn Eastman in Neuro Leave a comment