Hypersomnia following paramedian thalamic stroke: a report of 12 patients

Ann Neurol. 1996 Apr;39(4):471-80. doi: 10.1002/ana.410390409.


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.

MeSH terms

  • Adolescent
  • Adult
  • Cerebrovascular Disorders / complications*
  • Cerebrovascular Disorders / diagnosis
  • Circadian Rhythm
  • Disorders of Excessive Somnolence / etiology*
  • Disorders of Excessive Somnolence / physiopathology
  • Female
  • Follow-Up Studies
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Sleep
  • Sleep Stages
  • Thalamic Diseases / complications*
  • Thalamic Diseases / diagnosis
  • Wakefulness