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Cyclic alternating pattern

Characteristics of CAP – CAP consists of two long-lasting alternate EEG patterns in sleep. – It represents spontaneous cortical activity without sensory stimulation. – CAP […]

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Characteristics of CAP
– CAP consists of two long-lasting alternate EEG patterns in sleep.
– It represents spontaneous cortical activity without sensory stimulation.
– CAP is a marker of unstable sleep and occurs during NREM sleep.
– It is organized into phases A (phasic events) and B (background rhythm).
– CAP is influenced by autonomic and motor functions.

Clinical Significance of CAP
– In Lennox-Gastaut syndrome, CAP modulates clinical seizures and epileptic discharges.
– CAP is a marker of sleep instability and affects sleep disorders.
– Interaction between CAP and neurovegetative fluctuations determines pathophysiology.
– CAP is decreased in narcolepsy, multiple system atrophy, and with certain medications.
– CAP is related to arousals, impacting vigilance during sleep.

Research and Definitions
– Rechtschaffen and Kales developed standard sleep staging criteria in 1968.
– The AASM defined arousals as markers of sleep disruption in 1992.
– Spontaneous arousals increase over life according to Boselli et al. (1998).
– Studies by Terzano et al. (1985) and Parrino et al. (2012) highlight CAP’s significance.
– Eisensehr et al. (2001) studied CAP’s role in Lennox-Gastaut syndrome.

Impact of CAP on Sleep Disorders
– CAP influences the effect of CPAP treatment for obstructive sleep apnea.
– CAP serves as a master clock during stage transitions in sleep phases.
– CAP is crucial for maintaining regular fluctuations in EEG and autonomic functions.
– CAP is found during night-time recovery sleep after prolonged deprivation.
– Failure in the CAP-arousals relationship can lead to sleep disorders.

References
– Terzano et al. (1985) described CAP as a physiologic component of NREM sleep.
– Kryger’s book “Principles and Practice of Sleep Medicine” (2017) discusses CAP.
– Parrino et al. (2014) explain the cyclic alternating pattern in polysomnography.
– The study by Boselli et al. (1998) focuses on the effect of age on EEG arousals.
– Additional resources include publications by Parrino et al. (2012) and Eisensehr et al. (2001).

Cyclic alternating pattern (Wikipedia)

The cyclic alternating pattern (abbreviated CAP) is a pattern of two, long-lasting alternate electroencephalogram (EEG) patterns that occur in sleep, as described by Terzano, et al., in 1985. It is a pattern of spontaneous cortical activity, which is ongoing and in the absence of sensory stimulation. It is the reorganization of the sleeping brain challenged by the modification of environmental conditions and it is characterized by periodic abnormal electrocortical activity that recurs with a frequency of up to one minute. It is considered "the EEG marker of unstable sleep". CAP does not occur during REM. In Lennox-Gastaut syndrome, CAP modulates the occurrence of clinical seizures and generalized epileptic discharges by means of a gate-control mechanism.

CAP is a marker of sleep instability and it is found during non-rapid eye movement sleep. CAP is organized into sequences of successive cycles composed of two phases, A and B. Phase A involves phasic events, in other words, not continuous. Phase A subtypes of CAP allow adaptive adjustments of ongoing states to internal and external inputs. Phase B refers to background rhythm during CAP. Furthermore, CAP involves cerebral activities and is influenced by autonomic and motor functions. Interaction between CAP and neurovegetative fluctuations and motor events determine the pathophysiology of several sleep disorders and the effect of medication on continuous positive airway pressure (CPAP) treatment (CPAP is used to treat obstructive sleep apnea or OSA).

CAP is a marker of NREM instability and is also the "master clock" that accompanies the stage transitions maintained in sleep phases, noted in both the EEG and by autonomic functions through regular fluctuations. CAP is decreased in narcolepsy, multiple system atrophy, in certain cases of drug administration, with CPAP treatment for OSA, and during night-time recovery sleep after prolonged sleep deprivation. There is a relationship present between CAP and arousals that allows for adjustments of vigilance during sleep. If there is a failure in this relationship during sleep, sleep disorders may develop.

Rechtschaffen and Kales developed the standard criteria for sleep staging in 1968. In 1992, the AASM defined arousals as markers of sleep disruption, which is harmful for sleep. According to Boselli, et al., in 1998 it was noted that spontaneous arousals are natural in sleep and increase over life.

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