title: Hypersomnia following paramedian thalamic stroke: a report of 12 patients.
abstract: Paramedian thalamic stroke (PTS) is a cause of organic hypersomnia, which in the absence of systematic sleep-wake studies has been attributed to disruption of ascending activating impulses and considered a "dearoused" state. However, an increasing mount of data suggests a role of the thalamus in sleep regulation and raises the possibility that a sleep disturbance contributes to hypersomnia in PTS. We evaluated 12 patients with magnetic resonance imaging-proven isolated PTS and hypersomnia with 10 to >20 hours of sleep behavior per day. Nocturnal polysomnographic findings paralleled the severity of hypersomnia. All subjects had increased stage 1 NREM sleep, reduced stage 2 NREM sleep, and reduced numbers of sleep spindles. In patients with severe hypersomnia, slow-wave (stages 3-4) NREM sleep was often reduced, but there were no major REM sleep alterations. Daytime sleep behavior was associated mostly with stage 1 sleep by electroencephalogram; there was no correlation between hypersomnia and results of nap tests. We conclude that hypersomnia following PTS is accompanied by deficient arousal during the day and insufficient spindling and slow-wave sleep production at night. These observations support the hypothesis of a dual role of the paramedian thalamus as "final common pathway' for both maintenance of wakefulness and promotion of NREM sleep.
authors.affiliation: Department of Neurology, Inselspital-University Hospital, Bern Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Bassetti
authors.forename: J
authors.initials: J
authors.lastname: Mathis
authors.forename: M
authors.initials: M
authors.lastname: Gugger
authors.forename: K O
authors.initials: KO
authors.lastname: Lovblad
authors.forename: C W
authors.initials: CW
authors.lastname: Hess
mesh_terms: D000293:Adolescent; D000328:Adult; D002561:Cerebrovascular Disorders / Q000150:complications* / Q000175:diagnosis; D002940:Circadian Rhythm; D006970:Disorders of Excessive Somnolence / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012890:Sleep; D012894:Sleep Stages; D013786:Thalamic Diseases / Q000150:complications* / Q000175:diagnosis; D014851:Wakefulness