Hypersomnia Foundation

Posts Tagged 'polysomnography'

Ask the Doctor: Narcolepsy vs Idiopathic Hypersomnia

Ask the Doctor: Narcolepsy vs Idiopathic Hypersomnia:

What’s the Difference?

My 9-year-old son recently was diagnosed with IH but can’t exclude narcolepsy. We got a second opinion and the doctor agreed. I don’t understand why they don’t have a definitive answer. The doctors told me to not to worry about narcolepsy vs. hypersomnia. Can anyone help me understand the difference? And is it possible to have IH and beginning stages of narcolepsy?
Dr David Plante presenting at the Beyond Sleepy in the Mile High City Conference
Both narcolepsy and idiopathic hypersomnia (IH) are considered central disorders of hypersomnolence (CDH). They share similarities, most important of which is the requirement that patients with both disorders must experience significant excessive daytime sleepiness. From a diagnostic standpoint, sleep medicine uses the multiple sleep latency test (MSLT), a repeated nap study performed after polysomnography (PSG; an overnight sleep test), to help identify and characterize central disorders of hypersomnolence. One of the primary results of these tests used to determine whether a patient has narcolepsy or IH is based on the number of sleep onset REM periods (SOREMPs), during which individuals go into REM sleep much faster than is typical. Patients with narcolepsy have 2 or more SOREMPs on PSG/MSLT testing, where patients with IH do not.

There are differences in other clinical symptoms experienced by patients that can be used to help clarify whether a person has narcolepsy or IH. For example, patients with IH often sleep excessive amounts of time and have severe difficulty waking up after sleeping (i.e. excessive sleep inertia). Patients with narcolepsy frequently do not sleep excessive amounts of time, and may find brief naps refreshing. Many patients with narcolepsy also experience symptoms related to REM sleep instability such as sleep paralysis (waking from sleep in a paralyzed state) and hallucinations around sleep onset/offset, thought to be due to inappropriate combinations of REM sleep and waking brain function. In addition, some patients with narcolepsy experience cataplexy, the sudden loss of muscle tone in response to emotions such as laughter. Cataplexy is almost never seen outside of narcolepsy, and thus when patients have this symptom, there is high suspicion that the patient does indeed have narcolepsy.

Sometimes, the clinical history and results of PSG/MSLT testing do not neatly align. Although I do not have the specifics in the case of your son to comment definitively, it is certainly possible that the results of his sleep testing have shown he is pathologically sleepy consistent with IH, but did not have enough SOREMPs to be diagnosed with narcolepsy. He may also have clinical symptoms that are more suggestive of a narcolepsy diagnosis than IH, which is why there is some ambiguity around the diagnosis. Sometimes retesting can help clarify the diagnosis, but not always. Because initial treatment of both narcolepsy and IH often involves stimulants, oftentimes treatment is initiated for practical reasons to try to improve the patient’s symptoms, since the precise diagnosis may not alter initial clinical management, particularly in the early stages of treatment.

David T. Plante, M.D.
Assistant Professor, Department of Psychiatry
Program Director, Sleep Medicine Fellowship
University of Wisconsin School of Medicine and Public Health


Glossary of terms:

Central Disorders of hypersomnolence (CNS): As defined by the ICSD-3 rd –Include Narcolepsy Type 1, Narcolepsy Type 2, Idiopathic Hypersomnia, and Kleine- Levin Syndrome. They also include hypersomnolence caused by a medical disorder, medication or substance, psychiatric disorder and insufficient sleep disorder.

Rapid Eye Movement (REM) sleep: One of the two basic states of sleep. REM sleep, also known as dream sleep, is characterized by rapid eye movements, and more irregular breathing and heart rate compared to NREM sleep, the other basic state of sleep.

Sleep Onset REM Period (SOREMP): REM periods within 15 minutes of sleep onset, considered to support the diagnosis of narcolepsy.

Sleep Inertia: Feelings of grogginess and sleepiness that occur upon awakening that can result in impaired alertness and may interfere with the ability to perform mental or physical tasks.

Sleep Paralysis: involves the temporary inability to move, speak, or take a deep breath while falling asleep or waking up.

Hypnagogic or hypnopompic hallucinations: Sensory experiences involving the apparent perception of something that is not present, that occur at the transition from wakefulness to sleep (hypnagogic) or from sleep to wakefulness (hypnopompic). These hallucinations are typically visual in nature, but can affect other forms of sensation such as hearing or sense of touch.


 

Disclaimer for Ask The Doctor: The medical information provided is meant for educational purposes only and not as a substitute for professional medical care or advise.  Questions about a personal health condition should be discussed with your healthcare professional.

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A Pilot Study of tDCS Looks Promising for the Treatment of IH

A Pilot Study of tDCS Looks Promising for the Treatment of Idiopathic Hypersomnia

Background

Idiopathic hypersomnia (IH) can severely impact affected individuals’ family, employment, education, and leisure activities. And because there are no FDA-approved drugs for the treatment of IH — and even those drugs that are prescribed off label are often not effective or only somewhat effective — researchers have continued to seek out non-drug (nonpharmacologic) treatments for IH.
When a group of researchers in Italy heard about the encouraging results of a study in which investigators used a positively charged electrode (anodal) transcranial direct current stimulation (tDCS) to treat the effects of sleep deprivation, they decided to try tDCS in patients with IH. tDCS is a noninvasive brain stimulation technique that creates temporary changes in the excitability of the cortex – the outermost part of the brain, which is responsible for executive function. In the United States, tDCS and transcranial magnetic stimulation are approved for the treatment of depression.

Who Were the Participants and What Did They Do?

Three men and five women with IH that had not previously been treated took part in the study. These participants were also not taking any medication for other medical conditions or had been on a stable dose of their other medicines for at least 6 months. Their average age was 35. They underwent overnight sleep testing (polysomnography) to rule out any other sleep cause of their sleepiness.

Each person completed several tests of neurocognitive function and depression and the Epworth Sleepiness Scale (ESS) before starting the study (T0) and after the study was completed (T1). They also repeated the ESS two and four weeks after the study was completed. All participants also filled out a 10-point visual analog scale (VAS) to rate their sleepiness before each treatment session and kept a sleep diary for the duration of the trial. Finally, the participants completed a test of attention, the Attentional Network Task (ANT), at T0 and T1.

Who Were the Researchers and What Did They Do?
Dr. Ferini-Strambi and his colleagues in Milan, Italy, performed neurologic examinations on each of the participants and used statistical methods to analyze the results of testing and completed scales.

The researchers applied anodal tDCS by placing one electrode over the left dorsolateral prefrontal cortex, with the cathode over the contralateral orbit. The treatment consisted of 3 sessions of tDCS per week for 3 weeks delivered between 8 am and 11 am. The researchers chose this early time of day to allow the peak stimulating effects of tDSC to subside before typical evening bedtimes so as to not interfere with sleep.

What Were the Results of the Study?

Seven of the eight participants (87.5%) reported improvement in their daytime sleepiness, including for up to two weeks after the end of the study. The results of the ESS supported this reported improvement. Average ESS scores at T0 were 13.25 and at T1 were 7.5. VAS scores dropped from 4.96 at T0 to 1.57 at T1. Improvements in the ANT were significant and reflected faster reaction times at T1 than at T0.


What Were the Authors’ Conclusions?
“The lack of a sham condition represents the main limitation of our study. In any case, our investigation supports the idea that tDCS may provide a valid alternative for the management of [excessive daytime sleepiness] in the treatment of IH and opens the way to further controlled studies.”

(A sham condition is similar to the use of placebo in a drug trial. During a randomized controlled trial that is testing a device, some of the participants are assigned to receive treatment with the device as it would normally be used. Others are assigned to treatment that appears to be using the device, but the device is never turned on or, in this case, does not deliver the stimulation. When the test is masked, or blinded, the participants do not know to which group they are assigned. This type of testing provides stronger results.)

Editor’s note: This safe procedure, tDCS, is being used regularly now for the treatment of depression. We look forward to the results of a larger randomized controlled study in IH, which, according to Dr. Ferini-Strambi, is underway. For more information on tDCS, please visit this link at the National Institutes of Health.

Galbiati A, Abutalebi J, Iannaccone S, et al. The effects of transcranial direct current stimulation (tDCS) on idiopathic hypersomnia: a pilot study. Arch Ital Biol2016:154:1-5.

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