IDIOPATHIC HYPERSOMNIA
Section snippets
PREVALENCE
Because of the somewhat vague limits of idiopathic hypersomnia and its relative rarity, no prevalence study has ever been conducted. The only available data are the ratios of idiopathic hypersomnia to narcolepsy in different sleep disorders populations (Table 1). The ratios tend to decrease in the successive reports, probably due to the use of more stringent criteria, with the notable exception, however, of Aldrich's2 recent series.
AGE OF ONSET
In contrast with narcolepsy, a precise onset of idiopathic hypersomnia is often difficult to determine because of the insidious beginning of the condition and the difficulty, in young persons, of settling a posteriori a limit between long sleep and abnormally long sleep or normal wakefulness and impaired wakefulness. As is the case for narcolepsy and the Kleine-Levin syndrome, however, onset of this condition is most often during adolescence and rarely after the age of 30 years (Fig. 1).
CLINICAL FEATURES
The symptoms of idiopathic hypersomnia may vary.2 The most typical form, which Roth et al25 referred to as polysymptomatic, is characterized by excessive daytime sleepiness leading to unrefreshing prolonged naps, nocturnal sleep of long duration (as much as 12 hours or more), and sleep drunkenness. Subjects affected with this type of idiopathic hypersomnia often refrain from naps because of their spontaneous long duration and their unrefreshing nature. They use sophisticated alarm clocks and
COURSE
Idiopathic hypersomnia is a life-long disorder with no tendency to remit spontaneously. Complications are mostly social and professional.1, 8 Whether subjects' symptoms can be temporarily alleviated by having their sleep extended has not been investigated.
DIAGNOSTIC PROCEDURES
The diagnosis of idiopathic hypersomnia is mainly based on clinical features and the absence of associated symptoms such as cataplexy, snoring at night, periodic leg movements, or depression. Polysomnography and some other tests are necessary to rule out other sleep disorders, however. Indeed, in the author's experience, idiopathic hypersomnia is one of the most overdiagnosed sleep disorders.
The most widely used polysomnographic procedure is nocturnal sleep recording followed by a multiple
PATHOPHYSIOLOGY
In contrast with narcolepsy, no animal model of idiopathic hypersomnia is available; thus, experimental approaches are limited. Destruction of noradrenergic neurons of the rostral third of the locus coeruleus complex or of the noradrenergic bundle at the level of the isthmus in the cat, however, leads to hypersomnia with a proportional increase of NREM sleep and REM sleep, resembling idiopathic hypersomnia. This state is accompanied by a decrease of diencephalic norepinephrine.23
Not much
TREATMENT
Treatment of idiopathic hypersomnia is far from satisfactory. Stimulant drugs, such as dextroamphetamine, methylphenidate, mazindol, or pemoline, are the most commonly prescribed medications. These drugs often are less effective in idiopathic hypersomnia than in narcolepsy, however, and sometimes not as well tolerated. Recently, a new compound, modafinil, the mechanism of which is still unclear, produced good results in subjects with idiopathic hypersomnia.5 A double-blind controlled study has
SUMMARY
Idiopathic hypersomnia is not as well delineated as narcolepsy and its history is much more recent. There are at least two forms of the disorder: (1) a polysymptomatic form, characterized by excessive daytime sleepiness, nocturnal sleep of abnormally long duration, and signs of sleep drunkenness on awakening, and (2) a monosymptomatic form that manifests only by excessive daytime sleepiness. The most widely used laboratory procedures are nocturnal polysomnographic recording followed by an MSLT
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Cited by (54)
Narcolepsy and Idiopathic Hypersomnia
2023, Sleep Medicine ClinicsIdiopathic hypersomnia: a homogeneous or heterogeneous disease?
2021, Sleep MedicineCitation Excerpt :The term IH first appeared in the 1990 edition of the International Classification of Sleep Disorders [4]. Thanks predominantly to Billiard's clinical and scientific work [1,5,6], and a report by Bassetti and Aldrich [7] that advanced Roth's ideas of mono- and polysymptomatic forms of the disease [8], two forms of IH (with long and without long sleep time) appeared in the ICSD-2 [9]. IH with long sleep time was characterized by prolonged nocturnal sleep (more than 10 h) and long daily naps, both accompanied by sleep drunkenness; IH without long sleep time differed by the duration of the major sleep episode (longer than 6 h but less than 10 h) and by the absence of difficulty awakening in the morning.
Diagnostic Tools for Hypersomnias
2013, Encyclopedia of SleepDiagnostic Tools for Hypersomnias
2013, Encyclopedia of SleepIdiopathic Hypersomnia
2010, Principles and Practice of Sleep Medicine: Fifth EditionSleep, Breathing, and Neurologic Disorders
2009, Sleep Disorders Medicine: Basic Science, Technical Considerations, and Clinical Aspects: Third Edition
Address reprint requests to Michel Billiard, MD, Neurology B Department, Gui-de-Chauliac Hospital, 34295 Montpellier, Cedex 05, France
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From the Neurology B Department, Gui-de-Chauliac Hospital, Montpellier, France