4.1. Background and Clinical Significance
The association of epileptic seizures and sleep has been recognized since at least the 19th century. Gowers, as cited by Chokroverty, found that 21% of patients had seizures exclusively during the night, especially during transitions into and out of sleep, as well as 1 to 2 h after
awakening. With the introduction of the EEG, epileptic discharges during sleep were discovered. An increase in discharges during sleep has been a longstanding observation among patients with grand mal seizures. Sleep deprivation has been demonstrated to increase the yield of epileptiform findings even in the absence of sleep production, and may be more activating than sedated sleep; a more recent study of Degen et al., however, did not confirm significant differences in activation of epileptiform activity in patients with and without complete sleep deprivation. Even more recent studies of Malow et al. have shown that slow wave sleep is most likely to include spikes, whereas rapid eye movement (REM) sleep is the least likely to include discharges, even less than waking. Klein et al. found that sleep was more activating than HV for patients with definite interictal epileptiform discharges. Glick's recent review of the effects of sleep deprivation on EEG concluded that there is a prominent activating effect of light sleep on the EEG, but no evidence of an overall increase in discharge rate after sleep deprivation in waking or other sleep states. Regarding specificity of sleep recording, activity that is "sharp appearing" but seen only during wakefulness and not in sleep is less likely to be "epileptiform" than discharges that continue or increase during sleep.
Neuronal synchronization is the underlying basis for epileptiform discharges and ictal events. Non-REM sleep, mediated by thalamocortical input, is a time of increased synchronization when seizures occur in susceptible patients, and focal discharges tend to demonstrate a broader field. This lies in contradistinction to REM sleep, in which there is relative desynchronization of the EEG, and epileptiform discharges or seizures are rare.
In many laboratories, partial rather than complete sleep deprivation is used because it is less onerous for patients, less likely to precipitate seizures, and probably just as useful. We tell patients to cut down to half of their usual sleep amount, and to stay awake and not drink any caffeine in the morning before the EEG study is performed, to increase the likelihood of sleep. Technologists become adept at making the room quiet and warm, and coaxing the patient gently to sleep despite being in a laboratory setting. A second EEG ordered with sleep or sleep deprivation can increase the yield. Generally, conscious sedation, such as with chloral hydrate administration, is no longer offered, because special certification and staffing are required and make this problematic. However, conscious sedation is still used in some pediatric facilities in which a sleep EEG may be the only way to obtain an artifact-free tracing.
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Salvation For The Sleep Deprived The Ultimate Guide To Sleeping, Napping, Resting And Restoring Your Energy. Of the many things that we do just instinctively and do not give much of a thought to, sleep is probably the most prominent one. Most of us sleep only because we have to. We sleep because we cannot stay awake all 24 hours in the day.