Both interictal and ictal EEG phenomena are commonly activated by functional instability. The different non-REM sleep stages comprise long-lasting periods of cyclic alternating pattern (CAP) in which arousal fluctuates between 'A phases' of greater arousal and 'B phases' of less arousal, and periods in which vigilance maintains a tonic stability (non-CAP). Previous studies have revealed that phase A induces a marked enhancement of generalized EEG paroxysms, a minor though significant activation of focal lesional bursts, but no effect on rolandic functional spikes. Conversely, phase B exerts an inhibitory modulation, especially on bilateral interictal phenomena. Because of the opposite influence of phase A and phase B also on muscle tone, we assessed the amount and distribution of nocturnal partial motor seizures in 6 subjects affected by focal epilepsy. The polysomnograms included 45 motor seizures, 43 of which occurred during non-REM sleep. Nocturnal fits were significantly more frequent in stages 1 and 3 (P less than 0.0001). Among the non-REM seizures, 42 appeared in CAP (P less than 0.0001) and always in phase A. The transient arousal and the concomitant muscle tone activation expressed by phase A of CAP is likely to support the motor components of nocturnal seizures. Sleep analysis in terms of CAP and non-CAP provides a better understanding of the continuum from subclinical EEG paroxysms to clinical manifestations and of the relations between vigilance and seizure disorders.
Activation of partial seizures with motor signs during cyclic alternating pattern in human sleep / M. G. Terzano;L. Parrino;P. G. Garofalo;C. Durisotti;C. Filati-Roso. - In: EPILEPSY RESEARCH. - ISSN 0920-1211. - 10(1991), pp. 166-173.
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