News & Perspective
Drugs & Diseases
CME & Education
Video
Decision Point
Edition: English

Medscape

English
Deutsch
Español
Français
Português
UKNew

Univadis

Sign Up It's Free!
English Edition

Medscape

Univadis

    X
    Univadis from Medscape
    News & Perspective Drugs & Diseases CME & Education Video Decision Point
    Drugs & Diseases > Psychiatry

    Primary Hypersomnia Workup

    Updated: Mar 01, 2024
    • Author: Adrian Preda, MD, DFAPA; Chief Editor: Ana Hategan, MD, FRCPC  more...
    • Print
    Workup

    Approach Considerations

    Hypersomnolence is a diagnosis of exclusion. Other causes of excessive daytime somnolence should be ruled out before a diagnosis of hypersomnolence is made.

    A complete blood count (CBC), screening biochemistry tests, and thyroid-stimulating hormone tests are recommended to exclude common physical disorders that may present with excessive tiredness, often expressed as excessive sleepiness. A drug screen is indicated if substance-induced sleep disorder needs to be ruled out.

    As excessive sleepiness is essentially a self-reported, subjective complaint, a number of tests have been created with the goal of increasing the diagnosis. Commonly used scales for a quantitative, systematic assessment of excessive sleepiness are the Epworth Sleepiness Scale and the Stanford Sleepiness Scale. While helpful, these are essentially subjective scales, which raises questions about the characteristics of sleepiness when assessed by subjective methods (eg, the Epworth and Stanford sleepiness scales) versus objective ones (eg, polysomnography and the Multiple Sleep Latency Test). [79, 77]

    Next:

    Polysomnography and Multiple Sleep Latency Test

    Complete in-laboratory polysomnography (PSG) studies are essential to exclude other sleep disorders, particularly sleep breathing disorder, periodic limb movement disorder (PLMD), and narcolepsy. Nocturnal PSG findings in hypersomnolence include a short sleep latency, absence of arousals or awakenings, normal distribution of REM and NREM sleep, and normal to prolonged sleep duration. [78, 80]

    A PSG study is required prior to the Multiple Sleep Latency Test (MSLT) to objectively characterize preceding sleep and uncover potential causes of sleep fragmentation. The PSG must have confirmed at least 6 hours of sleep for the MSLT results to be considered in diagnosing hypersomnolence. Typical PSG findings in idiopathic hypersomnia (IH) include shortened sleep latency, increased sleep efficiency (often >90%), and increased slow-wave sleep [81, 13, 82, 53, 16]  It should be noted that these are nonspecific findings, as they could also be present in behaviorally induced insufficient sleep syndrome (BIISS). [16] Some studies report increased frequency of sleep spindles either throughout the sleep period or at the beginning and end of the night in IH. [83, 67]  It should be noted that sleep-onset REM periods (SOREMPs) are rare in IH. Indices for arousal, apnea-hypopnea, and periodic limb movements (PLMs) are generally less than 5 to 10 per hour. Of note, other studies indicate that PLMD in a patient with excessive daytime sleepiness who does not have a diagnosis of restless legs syndrome (RLS) should not preclude a diagnosis of IH, as occasionally higher indices are seen. [13, 82, 56, 57, 16]   

    Sleep latency on the MSLT is short, with a mean sleep latency time < 8 minutes. [6, 13, 82]  SOREMPs can occur in approximately 3–4% of naps but by definition will not occur more than once and can help differentiate IH from with narcolepsy, where SOREMPs (the occurrence of REM sleep within 20 minutes of sleep onset) are observed in two or more naps.

    Breathing-related sleep disturbances and frequent limb movements disrupting sleep are not present.

    The following PSG features are required for the diagnosis of hypersomnolence:

    • A sleep period that is normal or prolonged in duration

    • Normal REM sleep latency

    • A mean sleep latency score of less than 8 on the MSLT

    • Fewer than 2 sleep-onset REM periods.

    The MSLT evaluates the presence of pathologic sleepiness. The MSLT involves studying the patient during 5 daytime naps taken 2 hours apart. According to 2 studies, the mean MSLT score in hypersomnolence is slightly higher than the score in narcolepsy. The mean MSLT score was found to be 6.5 ± 3.2 minutes for IH versus 3.3 ± 3.3 minutes for narcolepsy. Further, narcolepsy is excluded by the absence of SOREMPs on the 5-nap MSLT.

    Previous
    Next:

    Electroencephalography (EEG)

    In recurrent primary hypersomnia (ie, Kleine-Levin syndrome), routine EEG studies during hypersomnia show a general slowing of the background rhythm and paroxysmal bursts of theta activity. Nocturnal PSG shows decreased sleep latency (< 10 min) and prolonged sleep duration. In addition, sleep-onset REM has been reported during symptomatic periods. (See the images below.) [62, 83, 6, 13, 82]

    Primary hypersomnia. Polysomnographic study demons Primary hypersomnia. Polysomnographic study demonstrates apnea (absence of carbon dioxide fluctuation indicating no flow), chest wall paradox, abrupt increase in tidal volume at the end of apnea, and oxygen desaturation. All of these features are consistent with obstructive sleep apnea.
    View Media Gallery
    Primary hypersomnia. In contrast to obstructive sl Primary hypersomnia. In contrast to obstructive sleep apnea, mixed apnea shows absence of respiratory efforts in the first segment of the apnea.
    View Media Gallery
    Primary hypersomnia. Periodic limb movements show Primary hypersomnia. Periodic limb movements show intermittent leg electromyogram activity accompanied by electroencephalogram arousals.
    View Media Gallery
    Previous
    Treatment & Management
     
     
    Media Gallery
    of 3
    Find Us On
    About
    About Medscape Privacy Policy Editorial Policy Cookies Manage Preferences Terms of Use Advertising Policy Help Center
    Membership
    Become a Member About You Professional Information Newsletters & Alerts Market Research
    App
    Medscape
    Editions
    English Deutsch Español Français Português UK
    All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC. This website also contains material copyrighted by 3rd parties.