Slow Activity in Focal Epilepsy During Sleep and Wakefulness.
BACKGROUND
We aimed to test differences between healthy subjects and patients with respect to slow wave activity during wakefulness and sleep.


METHODS
Fifteen patients affected by nonlesional focal epilepsy originating within temporal areas and fourteen matched controls underwent a 24-hour EEG recording. We studied the EEG power spectral density during wakefulness and sleep in delta (1-4 Hz), theta (5-7 Hz), alpha (8-11 Hz), sigma (12-15 Hz), and beta (16-20 Hz) bands.


RESULTS
During sleep, patients with focal epilepsy showed higher power from delta to beta frequency bands compared with controls. The effect was widespread for alpha band and above, while localized over the affected hemisphere for delta (sleep cycle 1, P = .006; sleep cycle 2, P = .008; sleep cycle 3, P = .017). The analysis of interhemispheric differences showed that the only frequency band stronger over the affected regions was the delta band during the first 2 sleep cycles (sleep cycle 1, P = .014; sleep cycle 2, P = .002). During wakefulness, patients showed higher delta/theta activity over the affected regions compared with controls.


CONCLUSIONS
Patients with focal epilepsy showed a pattern of power increases characterized by a selective slow wave activity enhancement over the epileptic regions during daytime and sleep. This phenomenon was stronger and asymmetric during the first sleep cycles.
1 Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.|2 Fondazione Alberto Sordi-Research Institute for Ageing, Rome, Italy.|3 Multimodal Functional Imaging Laboratory, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
Giovanni
G
Pellegrino
1 Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.|2 Fondazione Alberto Sordi-Research Institute for Ageing, Rome, Italy.
Mario
M
Tombini
4 Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy.
Giuseppe
G
Curcio
1 Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.|2 Fondazione Alberto Sordi-Research Institute for Ageing, Rome, Italy.
Chiara
C
Campana
1 Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.|2 Fondazione Alberto Sordi-Research Institute for Ageing, Rome, Italy.
Giovanni
G
Di Pino
1 Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.|2 Fondazione Alberto Sordi-Research Institute for Ageing, Rome, Italy.
Giovanni
G
Assenza
5 Danish Research Center for Magnetic Resonance (DRCMR), Hvidovre, Denmark.
Leo
L
Tomasevic
1 Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.|2 Fondazione Alberto Sordi-Research Institute for Ageing, Rome, Italy.
Vincenzo
V
Di Lazzaro
D000328:Adult; D000368:Aged; D004569:Electroencephalography / Q000379:methods; D004828:Epilepsies, Partial / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012890:Sleep / Q000502:physiology*; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
delta band; epilepsy; interictal; sleep; slowing; spike