No abstract

Objective: Slow waves are thought to mediate an overall reduction in synaptic strength during sleep. The specific contribution of the thalamus to this so-called synaptic renormalization is unknown. Thalamic stroke is associated with daytime sleepiness, along with changes to sleep electroencephalography and cognition, making it a unique "experiment of nature" to assess the relationship between sleep rhythms, synaptic renormalization, and daytime functions. Methods: Sleep was studied by polysomnography and high-density electroencephalography over 17 nights in patients with thalamic (n = 12) and 15 nights in patients with extrathalamic (n = 11) stroke. Sleep electroencephalographic overnight slow wave slope changes and their relationship with subjective daytime sleepiness, cognition, and other functional tests were assessed. Results: Thalamic and extrathalamic patients did not differ in terms of age, sleep duration, or apnea-hypopnea index. Conversely, overnight slope changes were reduced in a large cluster of electrodes in thalamic compared to extrathalamic stroke patients. This reduction was related to increased daytime sleepiness. No significant differences were found in other functional tests between the 2 groups. Interpretation: In patients with thalamic stroke, a reduction in overnight slow wave slope change and increased daytime sleepiness was found. Sleep-and wake-centered mechanisms for this relationship are discussed. Overall, this study suggests a central role of the thalamus in synaptic renormalization.

Neurologic disorders impact the ability of the brain to generate sleep, wake, and circadian functions. Preexisting or de novo sleep-wake-circadian pathologies are generally underdiagnosed in neurologic patients despite their major impact on onset, evolution, and outcome of neurologic disorders. Neurologic disorders are frequently accompanied by sleep-wake EEG changes. Extensive brain damage can lead to the absence of measurable differentiation between sleep and wakefulness (status dissociatus). New technologies will facilitate early detection and (long-term) monitoring of neurologic patients and the optimization of their clinical management.

No abstract